Comptia Network+ 1.0 Networking Fundamentals

VDSL (Very High Bit Rate DSL)

A variation of DSL where you could get very high speeds but the limitation is that the maximum distance to the DSLAM was 4,000 ft

1.2 MPLS pushing and popping

*Labels are "pushterm-38ed " onto packets as they enter the MPLS cloud * Labels are "popped" off on the wayterm-83 out

Fiber Optic Cable

*Uses light from a light-emitting diode (LED) or laser to transmit information through a thin glass fiber. *Immune to electromagnetic interference.

Internet Protocol (IP) Address

An assigned numerical label that is used to identify Internet communicating devices on a computer network.

Ethernet Switch

Increases scalability of a network by creating multiple collision domains

Challenge Handshake Authentication Protocol (CHAP)

Performs one-way authentication using a three-way handshake. Credentials are hashed before transmission

logical topology

Reflects the arrangement of devices and their communication.

FiN (Finished ) [TCP Flags ]

Used to tear down the virtual connections created using the three-way handshake and the SYN flag .

DHCP process

Uses DORA process: Discover Offer Request, Acknowledge

Client-server

Uses a dedicated server to provide access to files, scanners , printers and other resources * No client-to - client communication * Advantages - Performance - Administration - - Administration and backup is pretty easy here because we have one central machine , the server , that all of the resources are sitting on * Disadvantages - Cost - Complexity --- May cost more money because it requires dedicated hardware and os software.

1.8 Private Cloud Deployment Model

Your Own virtualized local data center

Differentiated Services ( DiffServ) -Soft QoS

* Has differentiation of data types where routers and switches can make decisions based on markings and can fluctuate traffic.

Network Address Translation (NAT)

* Used to conserve the limited supply of IPv4 addresses * Translates private IP addresses to public IP addresses for routing over public networks

1000BASE-SX

MMF 1000 Mbps 220-550 m

100BASE-SX

MMF 100 Mbps 300 meters

Synchronous

Uses a reference clock to coordinate the transmissions by both sender and receiver

Private (Non-routable) IP address

* Can be used by anyone any time , but only within their own local area network * Private IP ranges include those that start with either 10, 172, or 192.

URG (Urgent)[TCP flags]

* Similar to PSH and identifies incoming data as urgent . Process data immediately

URG flag

* Similar to PSH and identifies incoming data as urgent. * Main difference between PSH and URG is that push is used by the sender to indicate data with a higher priority level . While URG is sent to tell the recipient to process it immediately.

Hub and spoke

* Similar to Star but with WAN links instead of LAN connections and it used for connecting multiple sites

1.6 Automatic allocation

* Similar to dynamic allocation * DHCP server keeps a list of past assignments * You'll always get the same IP address

PAN (Personal Area Network)

* Smallest type of wired or wireless network and covers the least amount of area

1.6 NTP Stratum layers

* Some clocks are better than others - Your distance from the original reference clock is a stratum *Stratum 0 - Atomic clock , GPS clock *Stratum 1 - Synchronized to stratum 0 servers - Primary time servers * Stratum 2 - Sync'd to stratum 1 servers

1.8 Infrastructure as a service ( IaaS)

* Sometimes called Hardware as a Service (HaaS) - Outsource your equipment * You're still responsible for the management - And for the security * Your data is out there , but more within your control * Web server providers

Fibre Channel (FC)

* Special purpose hardware provide 1-16 Gbps of storage area network speed

Service Record (SRV)[DNS)

* Specifies a host and port for a specific service - such as voiceover IP , instant messaging and other services like that.

1.7 Fibre Channel over Ethernet

*Use Fibre Channel over an Ethernet Network - No special networking hardware needed - Usually integrates with an existing Fibre Channel infrastructure - Not routable

Baseband

*Use all available frequencies on a medium (Cable ) to transmit data

ACK (Acknowledgement ) [TCP Flags ]

*Used during the three-way handshake , but also used to acknowledge the successful receipt of packets

Link-Local / Local Use

*Used like a private IP in IPv4 that can only be used on the local area network and begins with FE80 * Can be only used on a local area network and it always is going to begin with FE80 as its first segment.

fully qualified domain name (FQDN)

The complete domain name of an Internet computer, such as www.CIWcertified.com.

Asynchronous

Uses start and stop bits to indicate when transmissions occur from the sender to the receiver

Point-to-Point Protocol over Ethernet (PPPoE)

* A network protocol for encapsulating point to point protocol frames inside Ethernet Frames

1.4 DAD (Duplicate Address Detection)

No duplicate IPs !

IPv4 Packet

* Consists of a source address , destination address, IP flags and protocol.

ACK (acknowledgment)

* Used during the three-way handshake , but also used to acknowledge the successful receipt of packets

FIN ( Finished ) flag

* Used to tear down the virtual connections created using the three-way handshake and the SYN flagR

RST flag ( Reset)

* Used when a client or server receives a packet that it was not expecting during the current connection

TIA/EIA 568B

Starts with Orange

QSFP+ (Transceiver)

Transceiver with speeds up to 41.2 Gbps

1.4 Binary Math

Use subtraction to convert decimal to binary Add to go from binary to decimal.

Fox & Hound (Tone Generator and Tone Probe)

Used in cable distribution networks to find breaks in the wire or identify and document your network

User-Network Interface (UNI)

Used to connect ATM switches and endpoints

Encryption

Used to scramble the data in transit to keep it secure from prying eyes and provide data confidentiality Examples ( TLS)

Deterministic model

* Very organized and orderly and requires an electronic token to transmit. - Wait turn to transmit data Ex. Token bus, Token ring Networks Zero collisions

InfiniBand

* Virtualized storage technology that uses a switched fabric technology and features very throughout and very low latency

Address Exhaustion

*Running of network addresses in IPv4

Service Advertisement

*Sending out of announcements to other devices on the network to state the services they offer.

Storage Area Network (SAN)

*Specialized LAN that transfers data at block-level with a special protocol.

Scope

* A list of valid IP addresses available for assignment or lease to a client computer or endpoint device on a given subnet

1.3 Subscriber Connector

"Stick and Click" Now this is why I call it the stick and click, because you stick it into the jack, and you hear the click.

1.3 Straight Tip Connector

"Stick and Twist" * I like to call the ST connectors, the stick and twist connector, because you're going to insert it into the jack, and then turn it about half a turn to the right until it locks in place. * Straight Tip (ST) fiber connections are commonly used in fiber optic connections in LAN networking applications

Layer 6

* Scripting languages * Standard Text * Pictures * Movie Files

3 Components of NTP

* Stratum * Clients * Servers

Cat 6

*1000 BASE-T *1000 Mbps (1 Gbps) *100 meters or * 10GBASE-T * 10 Gbps * 55 meters

1.4 Class C IP Address

1st octet value is 192-223 . Default subnet mask : 255.255.255.0 - This means that the network portion of the address is going to be the first , second and third octet. And we save the fourth octet for the host portion. - This means that for a class C network , you can only have 256 hosts on a single network. -256 x 1 = 256

STP Port States

Blocking Listening Learning Forwarding Disabled

Client

Can be any device that connects to the network

Private Direct Connection

Extends preexisting on-premise data center into the provider's network to directly connect to your virtual private cloud network

10GBASE-SR

MMF 10 Gbps 400 meters

Bandwidth

Theoretical measure of how much data could be transferred from a source to its destination

1.4 Classful subnetting

Very specific subnetting architecture • Not used since 1993 • But still referenced in casual conversation • Used as a starting point when subnetting • Standard values

802.11

Wireless networks that can operate in infrastructure or ad hoc modes.

Subnet mask

ex 255.255.255.0 - Used by the local device to determine what subnet it's on - The subnet mask isn't usually transmitted across the network - You'll ask for the subnet mask all the time - What's the subnet mask of this network * Every device has an IP address with two pieces: the client or host address and the server or network address. - IP addresses are either configured by a DHCP server or manually configured (static IP addresses). The subnet mask splits the IP address into the host and network addresses, thereby defining which part of the IP address belongs to the device and which part belongs to the network.

1.1 Payload

the carrying capacity of a packet or other transmission data unit.

Default route

the route that takes effect when no other route can be determined for a given destination. All packets for destinations not established in the routing table are sent via the default route. In most cases, the default route is to the router closest to the computer.

Hop

• A hop - A packet passes through a router • The next hop - The destination address of the next gateway • A router doesn't need to know how to get everywhere - It just needs to know how to get out of here - A default route handles everything not specifically listed • "Time to live" in IPv4, "hop limit" in IPv6 - Avoids a packet looping forever * Number of times that I have to go through a different router

1.6 Service Records (SRV)

• Find a specific service - Where is the Windows Domain Controller? Where is the instant messaging server? Where is the VoIP controller?

WAN (Wide Area Network)

• Generally connects LANs across a distance • And generally much slower than the LAN • Many different WAN technologies • Point-to-point serial, MPLS, etc. • Terrestrial and non-terrestrial

Partial Mesh

* Provide optimal routes between some sites but all the sites.

DSL (digital subscriber line)

3 types of DSL connections : - ADSL - SDSL - VDSL

1.3 TIA/EIA 568A

Starts with green

Globally-Routed

* Similar to IPv4s unicast class A,B,and C addresses and begins with 2000-3999

Data Terminal Equipment (DTE)

* "Endpoint" devices that connect to a piece of data communications equipment or DCE (e.g. laptops , desktops , servers and routers)

1.5 ICMP (Internet Control Message Protcol)

* "Text messaging" for your network devices * Another protocol carried by IP - Not used for data transfer * Devices can request and reply to administrative requests - Hey are you there ? / Yes I'm right here. * Devices can send messages when things don't go well - That network you're trying to reach is not reachable from here - Your time-to-live expire , just letting you know

Protocol Independent Multicast (PIM)

* * Lets routers know which interfaces have multicast receivers and allows clients to join a multicast group * Routes multicast traffic between routers and forms a multicast distribution tree. - Two different modes in PIM - PIM- DM , which is Dense Mode - PIM- SM or sparse mode

1.3 10 Gigabit Ethernet over fiber

* 10GBASE-SR - Short Range - Multimode fiber - 26 to 400 meters , depending on the fiber * 10GBASE-LR - Long range - Single-mode fiber - 10 kilometers maximum range

Cat 6a

* 10GBase-T * 10 Gbps * 100 meters

Class E IP Address

* 1st octet value : 240-255 * No default subnet mask * They're reserved for experimental purpose for research and development or study only *268 million IP addresses reserved for future use

1.4 Class B IP Address

* 1st octet value : 128-191 * Subnet mask of 255.255.0.0. * This means that the network portion of this address is going to be the first and second octets and the third and fourth octet is going to make up the host portion. - 256 *256 = 65,536

MAN (Metropolitan Area Network)

* A network in your city - Larger than a LAN , often smaller than a WAN *Common to see government ownership - They "own " the right -of -way

1.4 class A ipv4 addreses

* 1st octet value is between 1-127 * Default subnet mask of 255.0.0.0. - This means that with the class A network can have 256 x 256 x 256 hosts on a single network. - This means that there are 16.7 million possible host IP addresses available for a single network address portion in the class A.

1.3 40GBASE-T ( Cat 8)

* 40 gigabit per second Ethernet - 4 pair balanced twisted pair * Category 8 cable - Up to 30 meters

1.4 Tunneling

* 6 to 4 addressing - Send IPv6 based on existing IPv4 network - Creates an IPv6 based on the IPv4 address - Requires relay routers - No support for NAT 4in6 - Tunnel IPv4 Traffic on an IPv6 network

LAN (Local Area Network)

* A building or group of building - High- speed connectivity * Connects components within a limited distance * Ethernet (IEEE 802.3) or Wi-Fi ( IEEE 802.11)

Global System for Mobile Communications (GSM)

* A cellular technology that takes the voice during a call and then converts it to digital data * Much more widely supported across the globe * Has a sim card to identify the network

Code Division Multiple Access (CDMA)

* A cellular technology that uses code division to split up the channel * Are configured and locked to a certain cellular provider

1.2 Hybrid

* A combination of one or more physical topologies - Most networks are hybrid

BNC connector (Bayonet Neill-Concelman)

* A connector used on coaxial cable. * Used in older cabling. * Don't have to fully screw on.

Co-Located Datacenter

* A datacenter environment owned by another company - Essentially , you're going to rent space in their data center instead of having to build your own.

Default gateway

* A default gateway makes it possible for devices in one network to communicate with devices in another network. * ex 192.168.1.1 - The router that allows you to communicate outside of your local subnet - The default gateway must be an IP address on the local subnet

Virtual desktop

* A desktop computer that is run on a browser using web , laptop , tablet or phone * Bad for high performance computer requirements , like gaming , editing videos .

Wireless Acess point (WAP)

* A device that allows wireless devices to connect into a wired network

ADSL (asymmetric digital subscriber line)

* A different speed from on the download versus the upload

RIP (Routing Information Protocol)

* A distance vector protocol that uses hop count to figure out the fastest the fastest path. - maximum hops of 15 ; 16 is infinite - If it reaches 16 or more routers , the connection is going to be considered dead and is going to drop the packet and wait for you to retransmit it. * Is an interior gateway protocol that is used internal to your networks. * Updates every 30 seconds - Makes it hard to maintain convergence * Easy to configure * Runs over UDP

fully qualified domain name (FQDN)

* A domain name that is under a top-level provider Examples - www.google.com - mail.google.com - ftp.google.com

TCP/ IP Model

* A four-layer data communication mode developed by the United States Department of Defense. To some extent, it is similar to the OSI model. * Most modern computer networks are TCP/IP based *** Layers of the TCP/IP Model *** * Application layer - Contains Application , Presentation and Session layer from OSI Model * Transport : Transport Layer from OSI Model * Internet : Network layer from OSI model * Network Interface : Data Link and Physical layer from OSI model

Worldwide Interoperability for Microwave Access (WiMAX)

* A good alternative for cellular or DSL service , because it provides faster speeds . * Requires a antenna to installed on your roof or office.

Open Shortest Path First (OSPF)

* A link state protocol that uses cost * Cost is based on link speed between routers. - So basically go to the one with the fastest speed * Can be used on in any device

Scope

* A list of valid IP addresses available for assignment or lease to a client computer or endpoint device on a given subnet.

Hybrid routing protocols

* A little link-state, a little distance-vector - Not many examples of a hybrid routing protocol • BGP (Border Gateway Protocol) - Determines route based on paths, network policies, or configured rule-sets

Ports

* A logical opening on a system representing a service or application that's listening and waiting for traffic

1.1 Maximum Transmission Unit (MTU)

* A measurement representing the largest data packet that a network-connected device will accept. - Imagine it as being like a height limit for freeway underpasses or tunnels: Cars and trucks that exceed the height limit cannot fit through, just as packets that exceed the MTU of a network cannot pass through that network. - However, unlike cars and trucks, data packets that exceed MTU are broken up into smaller pieces so that they can fit through. This process is called fragmentation. Fragmented packets are reassembled once they reach their destination. - * Maximum IP packet to transmit ( But not fragment ) * Fragmentation slows things down - Losing a fragment loses an entire packet - Requires overhead along the path * Difficult to know the MTU all the way through the path - Automated methods are often inaccurate - Especially when ICMP is filtered

Satellite

* A method of using communication satellites located in space to connect a user to the Internet. * Can used anywhere as long as you - Can mount an antenna and has clear line of sight. * Satellite really makes it mark with mobile users on the go. * Speed is not very fast * Expensive compared to other options (Cable , Fiber) * High Latency - Its using satellites that are about 22,000 miles from the earth.

1.7 Distribution ( Network Architecture )

* A midpoint between the core and the users * Communication between access switches * Manage the path to the end users

1.6 Canonical name records ( CNAME)

* A name is an alias of another , canonical name - One physical server , multiple services

Zero Configuration (Zeroconf)

* A newer technology based on APIPA which provides a lot of the same features and some new ones * Can assign an IPv4 link-local address to a client * Can resolve computer names to IP addresses without the need for DNS by using mDNS (or multicast domain name service) *Can perform service discovery on a network . - Can see what things are connected and available for use. * In Apple this is called Bonjour * In Windows its called Link-Local Multicast Name Resolution (LLMNR) * In Linux its called SystemD

1.3 66 block

* A patch panel for analog voice - And some digital links * Left side is patched to the right - Easy to follow the path * Wire and a punch-down tool - No additional connectors required * Generally replaced by 110 blocks - Still seen in many installations * Used in older analog telephone systems and older CAT 3 networks and support a 25-pair cable that would run to the MDF or IDF

Border Gateway Protocol (BGP)

* A path vector that used the number of autonomous system hops instead of router hops * A standardized exterior gateway protocol designed to exchange routing and reachability information between autonomous systems (AS) on the Internet. * Not really concerned about how many routers you have go through , but how many systems you have to go through. * is considered the backbone of the Internet. - It is made up of lots of different autonomous systems as we move from one ISP to another. * Widespread utilization * Slow convergence - Doesn't converge very quickly because of the large scale of these networks. * On the exam the only exterior gateway to look for is BGP

DMZ (demilitarized zone)

* A perimeter network that protects an organization's internal local network from untrusted traffic

Spanning Tree Protocol (STP)

* A protocol that runs on our switches that helps us to solve loops.

Authentication Header

* A protocol within IPSec that provides integrity and authentication

Authentication Header (AH)

* A protocol within IPSec that provides integrity and authentication

F-type connector

* A screw-on type of connector that attaches to the cable box or to the wall jack * Used in Cable TV and cable modems for consumer applications

Exclusion Ranges

* A set of one or more IP addresses , included within the range of a defined scope , that you do not want to lease to DHCP clients. * Exclusion ranges assure that the server does not offer to DHCP clients on your network any addresses in these ranges.

Protocol Data Unit (PDU)

* A single unit of information transmitted in a computer network - L7 PDU

Protocol Data Unit (PDU)

* A single unit of information transmitted in a computer network L- PDU L7 PDU - Can be used for every layer

Plenum Cable

* A special coating put on a UTP or an STP cable that provides a fire-retardant cable chemical layer to the outer insulating jacket. term-96 * Plenum cables is for anything you cant see , such as ceilings , walls, raised floors , or air ducts

Plenum Cable

* A special coating put on a UTP or an STP cable that provides a fire-retardant chemical layer to the outer insulating jacket. *Plenum cables are for ceiling , walls , raised floors or air ducts.

1.7 Fibre Channel (FC)

* A specialized high-speed topology - connect servers to storage - 2-, 4-, 8- and 16-gigabit per second rates - Supported over both fiber and copper * Servers and storage connect to a Fibre Channel switch - Server (initiator) needs a FC interface - Storage (target) is commonly referenced by SCSI, SAS or SATA commands

Main Distribution Frame (MDF)

* A telecommunications closet which serves as the main starting point for all interior cabling

Cable Tray

* A unit or assembly of units that form a rigid structural system to securely support the cables and raceways

Cable Tray

* A unit or assembly of units that form a rigid structural system to securely support the cables and raceways * Best practice to minimize the number of cables that have to cross floors vertically

SDSL (Symmetric DSL)

* A variation of DSL that provides equal throughput both upstream and downstream between the customer and the carrier.

Subinterfaces

* A virtual interface that is created by dividing up one physical interface into multiple logical interfaces

1.2 Virtual Network Interface Card ( vNIC)

* A virtual machine needs a network interface * Configured and connected through the hypervisor - Enable additional features - VLAN , aggregation , multiple interfaces

Class of Service (CoS)

* A way to manage different types of traffic over a network by dividing similar types of traffic by classes. * CoS is sometimes used to refer to the Layer 2 QoS capabilities provided by Ethernet or ATM. - However, the term is used purely in the context of traffic classification as a set of traffic streams that will have common applications applied to them - . Hence, the term CoS is used to refer to the classification of an aggregate traffic stream into a number of constituent classes, where different actions are applied to each individual class of service . * It prioritizes traffic by allocating different levels of priority to different groups. - For example, it can give more priority to the voice traffic over others such as email or HTTP traffic. This enables network managers to refine connections to meet specific application needs.

1.2 DSL

* ADSL ( Asymmetric Digital Subscriber Line ) - Uses telephone lines * Download speed is faster than the upload speed ( Asymmetric ) - Approximately about a 10,000 foot limitation from the central office ( CO) - 200 Mbit /s Downstream / 20 Mbit/s upstream are common - Faster speeds may be possible if closer to the CO

Physical Layer (Layer 1 ) Examples

* Cables : Ethernet , coaxial , fiber *Wireless : Bluetooth , Wifi , NFC *Infrastructure devices : Hubs , access points , media converters - Whatever comes in is going out , there's no intelligence to it.

Public IP address (Routable)

* Can be accessed over the Internet and is assigned to the network by an Internet Service Provider * Routable IPs are publicly routable across the entire Internet and they're globally managed by ICANN.

ARP Table

* ARP is the protocol that bridges Layer 2 and Layer 3 of the OSI model , which in the TCP/IP stack is effectively gluing together the Ethernet and IP layers. - This critical function allows for the discovery of a devices MAC address based on its known IP address * So an ARP table is simply the method for storing the information discovered through ARP. - It's used to record the discovered MAC and IP address pairs of devices connected to a network. - Each device that connected to a network has its own ARP table , responsible for storing the address pairs that a specific device has communicated with.

Throughput

* Actual measure of how data transferred from a source to its destination.

Throughput

* Actual measure of how much data transferred from a source to its destination

Peer to peer

* All devices are both clients and servers - Everyone talks to everyone * Advantages - Easy to deploy - Low cost - No dedicated resources * Disadvantages - Cost , complexity - Inefficient for large networks - Poor scalability --- Administration and backup may be difficult because all of the files are located on different machines in different places --- Everyone can own and control their own machine and decide what they're sharing and what they're not sharing .

Star

* All devices are connected to a central device in this topology, the central hub acts like a server and the connecting nodes act like clients. * If the central device fails , the network fails

Dynamic Multipoint VPN (DMVPN)

* Allows Internet to be used as WAN connection for secure site-to-site connection

EUI-64

* Allows a host to assign itself a unique 64-bit IPv6 interface identifier called a EU-64 * This EUI 64 format is obtain by using the interface's 48 bit MAC address * The MAC address is first separated into two 24- bit portions. - The first half of the MAC address is going to contain the OUI or the Organizational Unique Identifier. - The second half is going to contain the specific network interface card. - In between is going to be a 16 bit hexadecimal value - So you would 24, 16 ,24 to make 64 bits in the EUI * The interface will use auto discovery to determine the network it is on and add the network portion of the IPv6 address which is going to be the first 64 bits inside of our addresses. * Now we're going to put that first 64 bits to represent the network in front of the 64 bits from the EUI-64 address we created from our MAC address to create a unicast globally routable IPv6 address

IPv6 Tunneling

* Allows an existing IPv4 router to carry IPv6 traffic

Internal DNS

* Allows cloud instances on the same network access each other using internal DNS names

Software--Defined Wide Area Network (SD-WAN)

* Allows for leveraging any combination of transport services to securely connect users to their applications *Software-based WAN architecture * To create an SD-WAN , you can use a centralized control function to securely and intelligently redirect the traffic across the WAN * If you are working at a large enterprise network and you have lots of branch offices and they're trying to move more and more into the cloud using things like IaaS PaaS and SaaS , then you may need to use an SD-WAN to increase the performance for your end users and reduce bottlenecks that were caused by your traditional centralized WAN architecture.

1.4 Network Address Translation

* Allows for routing of private IPs through a public IP.

Classless Interdomain Routing (CIDR) notation

* Allows for the borrowing some of those host bits and reassigning to the network portion * Shorthand rotation used to summarize continuous networks called using route aggregation *Class A = /8 *Class B = /16 *Class C =/24

802.1q (VLAN trunking)

* Allows physical network interfaces in a computing environment to be shared or multi-homed. * As data centers get more complex and the number of interconnected services increases, it's becoming more complex and expensive to provide dedicated cabling and network switch ports to allow for all the required connections * VLAN trunking allows for multiple virtual network connections to be maintained on a small number of physical adapters. *Each VLAN gets a unique VLAN tag and each packet on the network gets branded with the tag for the VLAN it's associated with. *Network devices on the network then only interact with packets that have the correct tags. - This allows multiple different logical networks to run on the same cable and switch infrastructure.

variable-length subnet mask (VLSM)

* Allows subnets of various sizes to be used and requires a routing protocol that supports it * Almost all routing protocols support this * RIP , * OSPF ,*IS-IS , *EIGRP , * BGP

Multiprotocol Label Switching (MPLS)

* Allows traffic to be dynamically routed based on load conditions and path availability * Going to support multiple protocols on the same network. * MPLS is not something you're going to use in your networks and is mainly used by service providers on their backbone networks.

F-type connector

* An F-type connector is a coaxial radiofrequency connector commonly used for cable television with an RG-6 cable. *RG-6 is a type of cable to transmit audio and video signals to devices such as television sets. It is also used with cable modems to transmit data.

Virtual IP addresses (VIP)

* An IP address that does not correlate to an actual physical network interface - Usually used for NAT Fault-tolerance , Virtualization * With an virtual IP address , you can actually configure that network interface card to respond to numerous IP addresses and have them all resolved back to your physical network interface ex 192.168.1.1 - The router that allows you to communicate outside of your local subnet - The default gateway must be an IP address on the local subnet

Service Level Agreement (SLA)

* An agreement used to guarantee a certain level of quality or speed you would require for your business use case.

1.3 Krone Block

* An alternative to the 110 block - Common in Europe *Options available for many purposes - Analog and digital communication - Different models can support higher frequencies * Proprietary European alternative to 110 block

Private (Non-routable) IP Address

* Can be used by anyone any time , but only within their own local area network * Private IP ranges include those that start with either 10, 172, or 192.

Spine-Leaf Architecture

* An alternative type of network architecture that focuses on the communication within the datacenter itself * Now the leaf layer is going to consist of all the access switches that aggregate traffic from the different servers and then connect directly into the spine layer or the networks core. * Now the leaf layer is going to consist of all the access switches that aggregate traffic from the different servers and then connect directly into the spine layer or the networks core. * Spine and leaf architecture can give faster speeds and lower latency than the traditional three-tiered hierarchy.

IP Address (Internet Protocol Address)

* An assigned numerical label that is used to identify Internet communicating devices on a computer network. * Used in Layer 3 of the OSI model Two protocols : IPv4 and IPv6

MDIX (media dependent interface crossover)

* An automated way to electronically simulate crossover cable even if using a straight-through patch cable

Ports

* An logical opening on a system representing a service or application that's listening and waiting for traffic. Ports are number from 0 to 65,535 * Well-known /Reserved Ports : 0 to 1023 * Ephemeral Ports : 1024 to 65,535 - Short-lived or temporary ports

Integrated Services Digital Network (ISDN)

* An older technology designed to carry voice ,video or data over B(bearer ) channels

PIM-SM: Shared Distribution Tree

* An optimal path between the source and last-hop routers is not initially created. Instead , a multicast source sends traffic directly to a rendezvous point (RP). All last-hop routers send join messages to the RP * Originally provides a suboptimal distribution tree, but when first multicast packet is received by last-hop router , then optimal distribution tree is created based on unicast routing table . Unneeded branches are pruned during shortest path tree (SPT) switchover *Used more because it works better and uses less resources and eventually gets the optimal distribution that we are looking for.

Cable Distribution System

* An organized system that connects the networks backbone in the MDF to the IDF and finally to the end user's wall jacks

BIX Block

* Another proprietary punch down block which is available in various sizes

Snowflake system

* Any system that is different from the standard configuration template used within your organization's IAC architecture * Keeping things consistent and using carefully-developed and tested scripts

TCP/IP model

* Application Layer - Application - Presentation - Session * Transport * Internet - Network Layer * Network Interface - Data Link - Physical 4 Layers in the TCP/IP Model

VLANs (Virtual Local Area Network)

* Are logical grouping of devices in the same broadcast domain. VLANs are usually configured on switches by placing interfaces into one broadcast domain and some interfaces into another. * A VLAN acts like a physical LAN ,but it allows hosts to be grouped together in the same broadcast domain even if they are not connected to the same switch.

Encapsulation (things to remember )

* As data moves from Layer 7 to Layer 1 , we are going to encapsulate that data and a header to each of those layers. * At Layer 4 ,we're going to add our source and destination ports * At Layer 3 , we add our source and destination IP addresses. * At Layer 2 , we add our source and destination MAC addresses * At Layer 1 , we're simply transmitting our Layer 2 frames as a series of one and zeros of a model

Dynamic Host Configuration Protocol (DHCP)

* Assigns an IP based on an assignable scope or pool of addresses and provides the ability to configure numerous other options within it. * Each IP is leased for a period of time and returns to the pool when lease expires * The IP Address Management manages the IPs being assigned and returned over time * DHCP is the modern implementation of BOOTP Variables through DHCP server : *IP address *Subnet mask * Default gateway * DNS/WINS server

Dynamic Host Configuration Protocol (DHCP)

* Assigns devices with IP addresses and also provides them a subnet mask , default gateway and DNS server

1.4 SLAAC ( Stateless Address Autoconfiguration )

* Automatically configure an IP address without a DHCP server

1.8 Public Cloud Deployment Model

* Available to everyone over the Internet

1.3 Twisted pair copper cabling

* Balanced pair operation - Two wires with equal and opposite signals - ( Transmit + , Transmit / Receive + , Receive - ) * The twist keeps a single wire constantly moving away from the interference - The opposite signals are compared on the other end * Pairs in the same cable have different twist rates * The twist is important . The more twists you have within an inch of the cable , the better the protection has from electromagnetic interference or EMI. * If you have less twists and the cable becomes more susceptible to more electromagnetic interference, and this will also mean you have slower speeds for your cable.

1.8 Desktop as a Service

* Basic application usage - Applications actually run on a remote server - Virtual Desktop Infrastructure (VDI) , Desktop as a Service ( DaaS) - Local device is a keyboard , mouse and screen * Minimal operating system on the client - No huge memory or CPU needs * Network connectivity - Big network requirement - Everything happens across the wire

1.7 Network Locations

* Branch office - A remote location - Client devices ,printers , switch /router/firewall *On-premises data center - Technology is located in-house - Requires power ,cooling and ongoing monitoring * Colocation - Share a data center with others - Local oversight and monitoring

Broadband

* Broadband - Transmission across multiple frequencies - Different traffic types * Divides bandwidth into separate channels Ex. If you have a TV service at your house, you're probably familiar with this because you have a single cable coming into your house, but it carries 200 or more channels. The user, then, is going to choose a single channel and the rest are going to be filtered out. * Data on the "cable" network - DOCSIS (Data Over Cable Service Interface Specification * High speed networking - 50 Mbit/s through 1000+ Mbit/s are common * Multiple services - Data , voice , video

Power Lines (WAN connections)

* Broadband over powerlines (BPL) support a 2.7 mbps connection.

T1 ,T3 ,E1

* Carrier :T1 - Signal Level :DS1 - # of T1 signals : 1 - # of Voice Channels : 24 - Speed : 1.544 Mbps *Carrier: T3 - Signal Level : DS3 - # of T1 signals : 28 - # of Voice Channels : 672 - Speed : 44.736 Mbps Carrier : E1 - Signal Level : n/a - # of T1 signals : n/a - # of Voice Channels : 30 - Speed : 2.0 Mbps

Wireless WAN Connections

* Cellular * Microwave * Satellite * High-frequency radio

Set Up Session ( Session Layer )

* Checking of user credentials and assigning numbers to sessions to help identify them

Set Up Session (Session Layer)

* Checking of user credentials and assigning numbers to sessions to help identify them

1.4 VLSM ( Variable Length Subnet Masks)

* Class-based networks are inefficient - The subnet mask is based on the network class * allow network administrators to define their own masks - Customize the subnet mask to specific network requirements * Use different subnet masks in the same classful network - 10.0.0.0./8 is the class A network - 10.0.1.0/24 and 10.0.8.0./26 would be VLSM * Number of subnets = 2 subnet bits * Hosts per subnet = 2^host bits -2

IPv4 classes

* Classes range from A-E. * To identify the class for an IP , you need to look at the first octet.

1.8 VM sprawl avoidance

* Click a button - You've built a server - Or multiple servers , networks , and firewalls * It becomes almost too easy to build instances - This can get out of hand very quickly * The virtual machines are sprawled everywhere - You aren't sure which VMs are related to which applications - It becomes extremely difficult to deprovision * Formal process and detailed documentation - You should have information on every virtual object

ANT+

* Collection and transfer of sensory data * Can be used with remote control systems things like tire pressure , TVs , lights ,etc * If you see ANT+ , think sensors

Wavelength Division Multiplexing (WDM)

* Combines multiple signals into one signal and sends over a single fiber optic strand using different wavelengths of the laser light source

1.3 WDM ( Wavelength- Division Multiplexing )

* Combines multiple signals into one signal and sends over a single fiber optic strand using different wavelengths of the light source.

NMAP (Network Mapper)

* Command tool that maps the network - Can do ping sweeps and look at what is up and available. - Look at each individual port - Can even figure out the operating system the remote server is running Zenmap is the graphical version of nmap

Point-to-Point Protocol (PPP)

* Commonly used Layer 2 protocol on dedicated leased lines to simultaneously transmit multiple Layer 3 protocols (IP, IPX) * Allows multilink interface * Looped link detection * Error detection * Authentication

Transmission Control Protocol (TCP)

* Connection-oriented protocol that is a reliable way to transport segments across the network * Three way handshake * Shows acknowledgement * Conducts a three-way handshake between client and a server and then establishes the connection * Reliable * Connection-oriented * Segment transmission and flow control through windowing *Segment sequencing *Acknowledges segments

IPv4 Packet

* Consists of a source address , destination address , IP flags, and protocol

MAC address Table

* Contains address information that the switch uses to forward traffic between ports. All MAC addresses in the address table are associated with one or more ports. - Dynamic address: a source MAC address that the switch learns and then ages when it is not in use. - Static address: A manually entered unicast address that does not age and that is not lost when the switch resets. * The address table lists the destination MAC address , the associated VLAN ID and port number associated with the address and the type (static or dynamic)

Intermediate Distribution Frame (IDF)

* Contains an edge switch , a patch panel , and other associated equipment to support the floor and offices nearest to it.

Straight- Through Cable (Patch Cable)

* Contains the exact same pinout on both ends of the cable

Straight-Through Cable(Patch Cable)

* Contains the exact same pinout on both ends of the cable . Connect a 568B cable to a 568 cable DTE to DCE DCE to DTE

Infrastructure Layer (SDN)

* Contains the network devices that receive information about where to move the data and then perform those movements

1.4 Seven Second Subnetting

* Convert IP address and subnet mask to decimal - Use chart to convert CIDR block notation and decimal - Same chart also shows the number of devices per subnet * Determine network/subnet address - Second chart shows the starting subnet boundary * Determine broadcast address - Chart below shows the ending subnet boundary * Calculate first and last usable IP address - Add one from network address , subtract one from broadcast address

Fiber distribution panels

* Convert fiber connections from one type to another

* 1.4 Magic Number process

* Convert the subnet mask to decimal * Identify the "interesting octet" * Calculate the " magic number " - 256 minus the interesting octet - Calculate the host range * Identify the network address - First address in the range * Identify the broadcast range - Last address in the range

Copper cables

* Copper cables can only go up to 100 meters and can carry speeds up to 10 Gbps

Three tier hierarchy

* Core *Distribution /Aggregation * Access /Edge * By using this type of hierarchy , we can get better performance , management , scalability and redundancy from our networks.

Calculating subnets

* Created subnets - 2^s Ex . /25 2^1 = 2 subnets 1 = number of borrowed bits

Layer 5 device examples

* H.323 - User to set up , maintain and tear down voice connections ( FaceTime , YouTube ). Operate on RTP ( Real Time Protocol) * NetBIOS - Used to share files over a network

Frame Relay

* Creates virtual circuits to connect remote LANs to a WAN * A WAN technology that specifies the physical and data link layers of digital telecommunication channels using a packet switching methodology. * Its supports the use of virtual circuits and point to multipoint connections. * It is commonly used to connect multiple smaller corporate office locations back to a larger centralized headquarters.

1.6 DHCP

* DHCP is a network management protocol that is used for internet protocol networks for the automatic assignment of IP addresses to devices, as well as to providing the subnet mask, default gateway, and DNS server for the device to use when it connects to the internet. * Provides an IP address to every machine on the network and eliminates configuration errors. * When the device gets a configuration from our DHCP server , it is getting four key pieces of information. - IP address - Subnet mask - Default gateway IP - DNS server IP * Operates over ports 67 and 68 using UDP.

DNS Hierarchy

* DNS is set up as a hierarchy . This occurs at five different level * Root *Top-Level Domain * Second- Level Domain * Subdomain *Host

Message Switching

* Data is divided into messages which may be stored and then forwarded * Similar idea to packet switching , but messages can be actually stored and forwarded like email.

Packet switching

* Data is divided into packets and then forwarded - It's going to keep going and switching that packet from place to place until it gets to its final destination. - Every time I send a letter out, it might take a different route to get there. I really don't care which route it takes, as long as it gets to its final destination. * Most networks use packet switching

Data Formatting ( Layer 6)

* Data is formatted by the computer to have compatibility between different devices *ASCII is a common one . - ASCII is the American Standard for Computer Information Interchange. - Text base language that ensures data is readable by receiving system - Negotiates data transfer syntax for the Application Layer ( Layer 7) * GIF , JPG , PNG are other common data formats

Data Formatting

* Data is formatted by the computer to have compatibility between different devices Examples -ASCII GIF JPG ASCII - Ensure data is readable by receiving system

Broadcast

* Data travels from a single source device to all devices on a destination network

Unicast

* Data travels from a single source to a single destination device *Used to identify a single interface - These are broken down into globally-routed unicast addresses and link local addresses.

1.1 Decapsulation

* Decapsulation is the process of removing the header and trailer information from a packet, as it moves toward its destination. * The destination device receives the data in its original form. * De-encapsulation in networking is performed at the receiver side or destination side as data moves from layer 1 to layer of the OSI model. As information travels up the layer of the OSI layer , information added from the sender's encapsulation process is removed layer by layer. * Move up the layer 1 to 7 is dec

Ad-hoc networking

* Decentralized wireless network which creates P2P connections and does not require a router or access point * Devices communicate amongst themselves -- It operates like a peer to peer network does , there's no routers , there's no access points.

Types of WAN Connections in enterprise and business networks

* Dedicated leased line * Circuit-switched *Packet-Switched

1.6 Address Records (A) (AAAA)

* Defines the IP address of a host - This is the most popular query * A records are for the IPv4 addresses - Modify the A record to change the host name to IP address resolution * AAAA records are for IPv6 addresses - The same DNS server , different records

Transport Layer

* Defines the level of service and status of the connection being used by TCP , UDP or RTP.

Transport Layer (TCP / IP Layer )

* Defines the level of service and the status of the connection being used by TCP , UDP , or RTP * TCP - connection full * UDP - connection less * RTP - real time

1.8 Infrastructure as code

* Describe an infrastructure - Define servers ,network , and applications as code * Modify the infrastructure and create versions -The same way you version application code * Use the description ( code ) to build other application instances - Build the same way every time based on the code * An important concept for cloud computing - Build a perfect version every time .

* Network Interface Layer

* Describes how to transmit bits across a network and determines how the network medium is going to be used

Network Interface Layer (TCP/IP)

* Describes how to transmit bits across a network and determines how the network medium is going to be used .

1.6 Start of Authority (SOA)

* Describes the DNS zone details * Structure - In SOA (Internet zone , Start of Authority ) with name of zone - Serial number - Refresh , retry and expiry timeframes - Caching duration / TTL ( Time to Live )

Ethernet Header

* Destination MAC Address * Source MAC address * EtherType * VLAN Tag

Reverse DNS lookup

* Determines what the domain name is for a given IP address * Trying to determine the host name based on a given IP

Application Layer

* Dictates how programs are going to interface with the transport layer by conducting session management . * This is the layer where the user is going to interact with the network through some sort of program - HTTP , Telnet , FTP , SSH, SNMP , DNS , SMTP , SSL/TLS

1.6 DKIM ( Domain Keys Identified Mail )

* Digitally sign your outgoing mail -Validated by the mail server , not usually seen by the end user - Put your public key in the DKIM TXT record

1.2 mGRE

* Multipoint Generic Routing Encapsulation - Used Extensively for Dynamic Multipoint VPN (DMVPN) - Common on Cisco routers * Your VPN build itself -Remote sites communicate to each other * Tunnels are built dynamically , on-demand - A dynamic mesh

MX (Mail Exchanger) record

* Directs emails to a mail server *MX record is going to be used to indicate how email messages should be routed when they're using the SMTP or Simple Mail Transfer Protocol over port 25. * When you create your MX records, you're also going to be able to provide the priority for each of these records - When it comes to setting the priority , the lower the number you enter , the higher the priority it is. * An MX record is used for outgoing (SMTP) and incoming (POP3/IMAP) traffic.

1.4 Dual-stack routing

* Dual-stack IPv4 and IPv6 - Run both at the same time - Interfaces will be assigned multiple address types *IPv4 - Configured with IPv4 addresses - Maintains an IPv4 routing table - Uses IPv4 dynamic routing protocols *IPv6 - configured with IPv6 addresses - Maintains a separate IPv6 routing table * Uses IPv6 dynamic routing protocols

Dynamic Assignment

* Dynamic allocation of IP addresses *Most SOHO network devices already run a DHCP server and is turned on by default

BOOTP (Bootstrap Protocol)

* Dynamically assigns IP addresses and allows a workstation to load a copy of their boot image over the network * BOOTP used a static database of IPs and Mac addresses.

Iterative Lookup

* Each DNS server responds directly to the client with an address for another DNS server that may have the correct Ip address

Collision Domain

* Each area of the network that shares a single segment * Devices operate in half-duplex mode when connected to a hub * Keep collision domains small inside your networks

1.7 Spine and leaf architecture

* Each leaf switch connects to each spine switch - Each spine switch connects to each leaf switch * Leaf switches do not connect to each other - Same for spine switches * Top-of-rack switching - Each leaf is one of the "top" of a physical network rack - May include a group of physical racks * Advantages - Simple cabling , redundant , fast * Disadvantages - Additional switches may be costly

Time-Division Multiplexing (TDM)

* Each session takes a turn , using time slots , to share the medium between all users

Stateless Address Autoconfiguration (SLAAC)

* Eliminates the need to obtain addresses or other configuration information from a central server.

Layer 7 Devices

* Email applications * Web Browsing * Domain Name Service (DNS) * File Transfer Protocolterm-46 * Remote accessterm-46

Tear Down Session

* Ending of a session after the transfer is done or when the other party disconnects

Tear Down Session ( Session Layer )

* Ending of a session after the transfer is done or when the other party disconnects

Virtual Private Network (VPN)

* Establishes a secure connection between on-premises network ,remote offices ,client devices and provider's global network. Ex. AWS ( Direct Connect Gateway) Azure (Azure Private Link)

DHCP reservation

* Excludes some IP addresses from being handed out to devices unless they meet a certain condition

Physical Topology

* Explains how network devices are physically connected or how devices are actually plugged into each other.

Common connectors in coaxial cables

* F-Type *BNC connector

Fiber optic cables

* FIber optic cables can go at least 40+ kms and can carry speeds of 60 or 70 tbps or more

SFP+ (Transceiver)

* Faster version of an SFP Speed up to 16 Gbps

1.3 UPC ( Ultra-polished connectors)

* Ferrule end-face radius polished at a zero degree angle * High return loss * Because of this lack of an angle , reflected light is going to be reflected straight back down towards the light source , it creates more noise and this causes a bit of signal loss. *MTRJ tends to use UPC more. * If the connector is blue , it's UPC.

Advanced Research Projects Agency Network (ARPAnet)

* First top-level domain that was defined for what would become the Internet

Application Layer ( SDN)

* Focuses on the communication resource requests or information about the network as a whole.

DHCP relay

* Forwards DHCP packets between clients and servers * DHCP relay is used when the client device and the DHCP server are not located on the same subnet or network Remember, if the DHCP client and server are on different network segments, the router and the client's network segment has to be configured with an IP helper address for DHCP to work properly and forward those requests over to the DHCP server. *DHCP operates using the User Datagram Protocol (UDP)

IP helper

* Forwards several different kinds of UDP broadcasts across the router and can be used in conjunction with the DHCP relay

1.3 Importance of cable

* Fundamental to network communication - Incredibly important foundation * Usually only get one good opportunity at building your cable infrastructure - Make it good! * The vast majority of wireless communication uses cables - Unless you're an amateur radio operator

Internet Corporation for Assigned Names and Numbers (ICANN)

* Globally manages and leases publicly routable IP addresses * Has 5 different groups who are responsible for handing out these public IPs based on where you actually live in the world -ARIN (North America) -LACNIC ( Latin America) - AFNIC ( Africa) - APNIC ( Asia Pacific) - RIPE (Europe)

Distribution / Aggregation

* Going to provide boundary definition by implementing access control lists and filters. * Normally, you're going to see layer three switches here being used because this distribution layer is going to ensure packets are being properly routed between different subnets and VLANs within your enterprise network.

1.6 DHCP pools

* Grouping of IP addresses - Each subnet has its own scope - 192.168.1.0./24 , - 192.168.2.0/24 - 192.168.3.0 /24 * A scope is generally a single contiguous pool of IP aterm-243ddresses - DHCP exceptions can be made inside of the scope

1.2 FIber

* High speed data communication - Frequencies of light * Higher installation cost than copper - Equipment is more costly and more difficult to repair - Communicate over long distances * Large installation in the WAN core - Supports very high data rates - SONET , wavelength division multiplexing * Fiber is slowly approaching the premises - Business and home use

EIGRP (Enhanced Interior Gateway Routing Protocol)

* Hybrid of distance vector and link state protocols that uses bandwidth and delay *Now this is an advanced distance vector protocol that uses both bandwidth and delay to make it a hybrid of the distance and link state protocols. * It does count the delay that exists, which is how many hops there are, as well as the cost that's available with each of those links to figure out their speed, making it that nice hybrid. * Now, this hybrid protocol was developed by Cisco as an upgrade to OSPF and it is very popular if you're using a Cisco-only network. * Because it's proprietary, meaning you can only use it with all Cisco products, you're not going to see it a lot if you're using Juniper or Brocade or other routers in your network. Again, it hasn't gotten the widespread acceptance that OSPF has because OSPF can be used on any device in any networks, not just Cisco.

Networking with IPv4

* IP address ex 192.168.1.165 - Every device needs a unique IP address

Four components of fully-configured client

* IP address * Subnet mask * Default gateway * Server address

1.6 Scope Properties

* IP address range ( and excluded address ) * Subnet mask * Lease durations * Other scope options - DNS server , default gateway , WINS Server

Windows Internet Name Service (WINS)

* Identifies NETBIOS systems on a TCP/IP network and converts those NetBIOS names to IP addresses * WINS is like DNS but only for Windows Domain Environments

PIM-DM: Pruning

* If a router receives multicast traffic in the initial flood and the traffic is not needed then the router sends a prune message asking to be removed from the source distribution tree. After Pruning * After sending prune messages , the resulting source distribution tree has an optimal path between source router and last-hop router . Flood and prune repeat every three minutes , which can cause excessive performance impact on the network

High Frequency Radio

* Implementation varies from country to country based on frequencies * Common uses for VHF are FM radio broadcasting, television broadcasting, two way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometers with radio modems, amateur radio, and marine communications.

Layer 2

* In Layer 2 , the data link layer, you are going to encapsulate the data by adding an Ethernet Header. - Includes Destination MAC Address , Source MAC address , EtherType and VLAN Tag. * EtherType field is used to indicate which protocol is encapsulated in the payload event frame. ( IPv4 or IPV6) *By default ethernet uses an MTU of 1500 bytes as its maximum size.

distance-vector routing protocol

* Information passed between routers contains network details - How many "hops" away is another network? - The deciding "vector" is the "distance" • Usually automatic - Very little configuration • Good for smaller networks - Doesn't scale well to very large networks • RIP (Routing Information Protocol), EIGRP (Enhanced Interior Gateway Routing Protocol)

link-state routing protocol

* Information passed between routers is related to the current connectivity - If it's up, you can get there. - If it's down, you can't. • Consider the speed of the link - Faster is always better, right? * If you are going to be using a link-state vector , you are going to be concerned more with link speed and what is the quickest method of getting there. * Faster convergence time than distance-vectors and use cost or other factors as a metric * Each router is going to construct its own relative shortest path based on where it sees itself in the logical diagram and then it calculates the distance of how it's going to get to the other places. • Very scalable - Used most often in large networks • OSPF (Open Shortest Path First) - Large, scalable routing protocol

Different names for NAT IP addreses

* Inside local - Private IP address referencing an inside device * Inside global - Public IP address referencing an inside device * Outside global - Public IP address referencing an outside device * Outside local - Private IP address referencing an outside device * Anytime you global think public , anytime you see local see private

Wireless Mesh

* Interconnection of different types of nodes , devices , or radios

1.3 Structured cabling standards

* International ISO / IEC 11801 cabling standards - Defines classes of networking standards * Telecommunications Industry Association ( TIA) - Standards , market analysis , trade shows , government affairs , etc - ANSI / TIA -568: Commercial Building Telecommunications Cabling Standard * Commonly referenced for pin and pair assignments of eight-conductor 100-ohm balanced twisted pair cabling - T568A and T568B

1.4 IPv6 addressing

* Internet Protocol v6 - 128-bit address - 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (340 undecillion) - * 6.8 billion people could have 5,000,000,000,000,000,000,000,000,000 addresses each' * Larger address space * No Broadcasts * No fragmentation * Can coexist with IPv4 * Simplified header * An IPv6 address uses hexadecimal digits and allows the use of shorthand rotation - Uses double colon to separate leading zeroes . And is also broke down in 4 digits

1.5 Lots of Ports

* Ipv4 sockets - Server IP address , protocol , server application port number - Client IP address , protocol ,client port number * Well Known Ports and Reserved Ports 0 to 1023

Multiplexing

* Is getting more out of a limited network . * Examples are FDM ,StatDM and TDM.

Patch Panel

* Keeps a data center or server room organized by making it easy to move ,add , or change a cable distribution infrastructure * Cheap and inexpensive and they protect me from causing damage to the more expensive network components

Orchestration

* Process of arranging or coordinating the installation and configuration of multiple systems * If you're using some robust orchestration , that been properly configured and tested : - Lower costs - Speed up deployments -Increase security

Synchronous Optical Network (SONET)

* Layer 1 Technology that uses fiber as its media and has high data rates which range from 155 Mbps to 10 Gbps or more. * Uses Transport Layer 2 encryption like ATM or Asynchronous Transfer Mode * Covers distances between 20 km to 250 km or more * ATM has fixed header of 5 Bytes and a payload of 48 Bytes * Remember ATM deals with FIber and SONET networks

1.2 MPLS

* Learning from ATM and Frame Relay * Packets through the WAN have a label (routing decisions are easy ) * Any transport medium , any protocol inside - IP packets , ATM cells , Ethernet frames - OSI layer 2.5 * Increasingly common WAN technology

1.6 DHCP leases

* Leasing your address - It's only temporary - But it can seem permanent * Allocation - Assigned a lease time by the DHCP server - Administratively configured * Reallocation - Reboot your computer - Confirms the lease * Workstation can also manually release the IP address - Moving to another subnet * In home networks the default lease time is about 24 hours usually. * Corporate networks you can choose longer lease times like 7 or 30 days.

IGMP (Internet Group Management Protocol)

* Lets routers know which interfaces have multicast receivers and allows clients to join a multicast group *IGMPv1 - Clients requests joining the group and is asked every 60 seconds if it wants to remain in the group - Router would ask do you still want to be here. *IGMPv2- Clients can send a leave message to exit multicast group - Clients had the ability to send leave messages to exit the group when they wanted. - Essentially now , the router's going to assume you want to be there until you told it that you didn't want to be there. IGMPv3 - Client can request multicast only from specific server and allows source-specific multicast (SSM) and multiple video streams to a single multicast stream

Scripting

* Lets you perform a series of actions in a particular order or sequence and it can even include some basic logic to ensure the right things are being deployed based on current conditions .

1.6 Managing DHCP in the enterprise

* Limited Communication range - Uses the IPv4 broadcast domain - Stops at a router * Multiple servers needed for redundancy - Across different locations * Scalability is always an issue - May not want (or need ) to manage - DHCP servers at every remote location * You're going to need a little helper - Send DHCP requests across broadcast domains

AAAA records

* Links a hostname to an IPv6 address - For Ipv6 addresses

1.7 SAN ( Storage Area Networks )

* Looks and feels like a local storage device - Block level access - Very efficient reading and writing * Requires a lot of bandwidth - May use an isolated network and high speed network technologies

IP Small Computer System Interface (iSCSI)

* Lowers cost and relies on configuration that allows jumbo frames over the network

1.3 Mechanical Transfer Registered Jack

* MTRJ is a fiber optic cable connector that's very popular and widely used with networking devices because it has a smaller form factor. * It's much smaller than the other three we talked about. Each MTRJ connector is going to have both the transmit and receive pins terminated inside a single plastic connector. And this is about half the size of an SC, ST, or LC connector. * This means that by using an MTRJ, you can have a switch that fits 24 fiber ports in the same chassis size as a regular RJ45 24 port copper switch, whereas with ST, SC, or LC, you'd only be able to get about 12 switch ports in there. *Now, often you're going to see MTRJ used on fiber switches, and they're going to connect to fiber patch distribution panels on one side, and the other side, will convert it to SC, ST, or LC, for distribution out to a wall jack into an office. * Now remember, all of these cables are fiber, and they're all made of glass. And when we connect these cables to the connectors, these connectors have two different styles that we can contact with those jacks.

1.1 Troubleshooting MTU

* MTU sizes are usually configured once - Based on the network infrastructure and don't change often * A significant concern for tunneled traffic - The tunnel may be smaller than your local Ethernet segment * What if you send packets with Don't Fterm-58ragment (DF) set ? - Routers will respond back and tell you to fragment - Hope you get the ICMP message ! * Troubleshoot using ping - Ping with DF and force a maximum size of 1472 bytes * Windows : ping -f -1 1472 8.8.8.8

DNS Resolver /DNS Cache

* Makes a local copy of every DNS entry it resolves as you connect to websites

Static Assignment

* Manually typing in the IP address for the host , its subnet mask , default gateway and DNS server * Static assignment of IP address is impractical on large enterprise networks

1.6 Recursive and Iterative DNS queries

* Many ways to get what you need * Recursive query - Delegate the lookup to a DNS Server - The DNS server does the work and reports back - Large DNS cache provides a speed advantage * Iterative query - Do all of the queries yourself - Your DNS cache is specific to you

Copper Wire (WAN connections )

* May use : - UTP - STP - Coax * These copper cables can support both analog and digital connections * UTP /STP - Dial-up , ISDN , E1 , T1 * Coax - Cable Modem

Metro Ethernet

* Metro- E - Metropolitan-area network - A contained regional area * Connect your sites with Ethernet - A common standard * The provider network is optical - Local fiber network - Wavelength division multiplexing - High speed , multiple wavelengths of light

Cloud-Based Datacenter

* Migrating company data out of own server and datacenters and into a cloud service provider's servers and datacenters

1.3 Rj-45 connector

* Most commonly used connector in our networks. A plastic eight pin connector. * Used for data networks

Multicast

* Multicast addresses messages for a specific group of devices in a network. * Used to identify a set of interfaces and begins with FF

Mesh

* Multiple links to the same place - Full connected - Partially connected * Redundancy , fault-tolerance , load balancing * Used in wide area networks ( WANs) - Fully meshed and partially meshed

Krone Block

* Proprietary European alternative to 110 block

1.6 NTP clients and servers

* NTP server - Respond to time requests from NTP clients - Does not modify their own time * NTP client - Requests time updates from NTP server * NTP client /server - Requests time updates from an NTP server - Responds to time requests from other NTP clients *Important to plan your NTP strategy - Which devices are clients , servers , and client/servers ?

1.4 The construction of a subnet

* Network address - The first IP address of a subnet - Set all host bits to 0 ( 0 decimal) * First usable host address - One number higher than the network address *Network broadcast address - The last IP address of a subnet - Set all host bits to 1 ( 255 decimal ) *Last usuable host address : - One number lower than the broadcast address

1.4 Four Important Addresses for Magic Number Subnetting

* Network address / subnet ID - The first address in the subnet * Broadcast address - The last address in the subnet * First available host address - One more than the network address * Last available host address - One less than the broadcast address

Synchronous mode

* Network devices agree on clocking method to indicate beginning and end of frames and can use control characters.

Asynchronous mode

* Network devices reference their own internal clocks and use start and stop bits

Isochronous mode

* Network devices use a common reference clock source and create time slots for transmission

1.4 NDP (Neighbor Discovery Protocol)

* No broadcast - Operates using multicast over ICMPv6 * Neighbor MAC Discovery - Replaces the IPv4 ARP

1.8 Platform as a Service ( PaaS)

* No servers , no software , no maintenance , no HVAC - Someone else handles the platform , you handle the development * You don't have direct control of the data , people or infrastructure - Trained security professionals are watching your stuff - Choose carefully * Put the building blocks together - Develop your app from what's available on the platform - SalesForce.com

Fiber (Wan Connections)

* Not subject to EMI like copper connections. *More expensive than copper cables

Scope options

* Now, when you're configuring your DHCP server, one of the things you can configure is your scope options. - This allows you to configure a bunch of different things, but the most common are the subnet mask that is going to be applied to all the devices requesting that configuration, the default router or gateway that these devices should use, and the DNS server to include the IP address configuration for those devices, as well as the least time for the IP address.

1.3 Media converter

* OSI Layer 1 - Physical layer signal conversion * Extend a copper wire over a long distance - Convert it to fiber and back again * You have fiber - The switch only has copper ports * Almost always powered - Especially fiber to copper * Converts media from one format to another * They conduct layer one to layer one conversions

Virtual Machine Escape

* Occurs when an attacker breaks out of one of the isolated VMs and begins to directly interact with the underlying hypervisor *Host virtual servers on the same server as other VMs in the same network

Switching Loop

* Occurs when more than one link exists between the source and destination devices.

1.8 Designing the cloud

* On-demand computing power - Click a button * Elasticity - Scale up or down as needed * Applications also scale - Scalability for large implementations - Access from anywhere * Multitenancy - Many different clients are using the same cloud infrastructure

1.8 Software as a service (SaaS)

* On-demand software - No local installation - Why manage your own email distribution ? Or payroll ? * Central management of data and applications - Your data i s out there * A complete application offering - No development work required * Google Mail is an example

Full mesh

* Optimal routing is always available as every node connects to every other node. * Every machine can go direct with one jump over to the machine they want to get to.

PAP , CHAP , MSCHAP

* PAP - sent in the clear *CHAP - hashed credentials * MS-CHAP - Hashed credential and most secure

Password Authentication Protocol (PAP)

* Performs one-way authentication between client and server * Sent in clear text - Anyone could read the authentication and steal it from you

1.3 Fiber distribution panel

* Permanent fiber installation - Patch panel at both ends * Fiber bend radius - Breaks when bent too tightly * Often includes a service loop - Extra fiber for future changes * Fiber distribution panels convert fiber connections from one type to another

1.5 Non-ephemeral ports

* Permanent port numbers - Ports 0 through 1,023 - Usually on a server or service

Media Access Control (MAC)

* Physical addressing system of a device which operates on a logical topology - Every manufacturer of a network card uses a 48-bit address assigned to a network interface card (NIC) * Uses a 12 digit hexadecimal number to represent the MAC addresses - Ex : D2:51:F1:3A:34:65 - These MAC addresses are always written hexadecimally wherein each of the letters or numbers are considered four bits . * The first 24 bits or six letters as you can see here identifies the particular vendor who made that card - Ex . D2:51:F1 * The second half is going to represent the exact machine it belongs to . - Ex: 3A:34:65

Port Forwarding

* Port forwarding is an application of network address translation that redirects a communication request from one address and port number combination to another while the packets are traversing a network gateway such as a router or firewall . * Sometimes called port mapping , allows computers or servers in private networks to connect over the Internet with other public or private computers or services.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

* Prevents collisions by using carrier-sensing to defer transmissions until no other stations are transmitting * The more devices you have communicating on a single network segment , the more collisions you're going to have.

Software Defined Networking (SDN)

* Provides an easy to use front end to configure physical and virtual devices throughout the network. * Enables the network to be intelligently and centrally controlled or programmed using software applications * When it comes to SDN , there are several pieces that we need to consider including : - Application Layer - Control Layer - Infrastructure Layer - Management Plane

Encapsulating Security Payload (ESP)

* Provides encryption and integrity for the data packets sent over IPSec

Encapsulating Security Payload (ESP)

* Provides encryption and integrity for the data packets sent over IPsec

Z-Wave

* Provides short-range , low-latency data transfer with slower rates and less power consumption than Wi-Fi * Mainly used for home automation

External DNS

* Records created around the domain names from a central authority and used on the public Internet

East-West Traffic

* Refers to data flow within a datacenter * Modern cloud infrastructure can produce large volumes of East-West traffic than traditional infrastructure . * All VMs , containers , network devices and network controllers inside a private network generate communicate traffic.

1.6 Zone Transfers

* Replicate a DNS database - The primary DNS server has the primary copy of the zone information . *Synchronize to a secondary server - Provide redundancy * Triggered by referencing the serial number - If the serial number increases , there must have been a change * Full zone transfers can be a security risk - Attackers can use the data as reconnaissance

1.6 Recursive DNS query

* Request sent to local name server * Name server queries root server * Root response sent to local name server * Name server queries.com name server * .com Response sent to local name server * Name server queries specific domain server * Domain server responds to name server * Name server provides result to local device * Answer is cache locally

1.6 Iterative DNS query

* Request sent to local name server * Response is the name of a more specific DNS Server * Request sent to a root server * Response is the name of a more specific DNS server * Request is sent to the .com server * Response is the name of a more specific DNS Server * request made to the authoritative server * Authoritative server provides result * Answer is cached locally

Twisted Pair Connectors

* Rj45 and RJ11 are twisted pair connectors *RJ45 is an eight pin connector * RJ45 is used in Ethernet-based networks *RJ11 is a six-pin connector * RJ11 is used in phone systems * RJ stands for Registered Jack * Registered Jack - Used to carry voice or data which specifies the standards a device needs to meet to connect the phone or data network

1.4 Discover Routers

* Router Solicitation (RS) and Router Advertisement (RA)

Layer 3 devices

* Routers ( Circle with four arrows) * Multilayer switches - Works like a regular switch and a router combined - Has both features of a layer 2 switch and a layer 3 router in the single device , which is why it's considered a layer 3 device. ** REMEMBER for the exam , that a switch is always a layer 2 device , unless they specifically tell that its a multilayer switch * If its a multilayer switch its layer 3 IPv4 , and IPv6 are layer 3 protocols .

IP Dual Stack

* Running both the IPv4 and IPV6 protocols by your network devices simultaneously

Plain Old Telephone Service (POTS)

* Runs on public switched telephone network (PSTN) consists of telephone carriers from around the world * Analog connections using PSTN are called POTS connections

Layer 6 Devices

* Scripting Languages - XML, HTML, PHP * Standard Text * Pictures * Movie Files * Encryption Algorithms

1.7 iSCI (Internet Small Computer Systems Interface )

* Send SCSI commands over an IP network - Created by IBM and Cisco , now an RFC standard * Makes a remote disk look and operate like a local disk - Like Fibre Channel * Can be managed quite well in software - Drivers available for many operating systems - No proprietary topologies or hardware needed

Zone Transfer _

* Sends DNS record data from the primary name server to a secondary nameserver *When this occurs, the first record that's transferred over is the SOA record, that Start of Authority. And this is used by the secondary server to see if the other records need to be updated because the Start of Authority record contains a serial number that acts as a type of versioning. * When a zone transfer occurs, this is going to use the TCP protocol to do the data transfer. This ensures the data's going to be sent over successfully from the primary server to the secondary server and verify it has been received there.

1.2 Virtual Networks

* Server farm with 100 individual computers - It's a big farm * All servers are connected with enterprise switches and routers - With redundancy * Migrate 100 physical servers to one physical server - With 100 virtual servers inside * What happens to the network ?

Access Control list (ACL)

* Set of rules applied to router interfaces that permit or deny certain traffic. * Switch - Based on Mac Address * Router - IP address *Firewall - IP address or port * ACLs are going to based on - Source/destination IP - Source/destination port -Source/destination MAC

1.8 Community Cloud Deployment Model

* Several Organizations share the same resources

Zone Transfer

* Sharing of information between DNS servers about which domain they have and their associated IP addresses.

Port Address Translation (PAT)

* Sharing of one public IP by multiple private IP addresses which gives a many-to-one translation *Uses port to keep track of the different segments that we're doing *Router sends a request from its source address and its going to specify a port number to keep track of those requests * Port forwarding is an application of network address translation that redirects a communication request from one address and port number combination to another while the packets are traversing a network gateway such as a router or firewall . *PAT is a type of dynamic NAT which can map multiple private IP addresses to a single public IP address by using port forwarding.

5G

* Split up to 3 frequency bands: - Low band + Frequency : 600-800 Mhz + Speed: 30-250 Mbps + The benefits of using low-band frequency range is it has a longer range and can cover an area similar to size to the older 4G networks. - Mid band + Frequency: 2.5-3.7 GHz + Speed: 100-900 Mbps + Most 5G deployments are done in this band as it provides a good balance of coverage with those higher speeds. - High band + Frequency : 25-39 GHz + Speed : Extremely high speed (in Gbps) + Range of these towers is small and the signal can easily be blocked by walls ,windows and other objects

Class C Private IP address range

* Starting Value : 192.168 * IP range: 192.168.0.0 - 192.168.255.255 * 65,536 IP address (256*256)

Class B Private IP range

* Starting Value : 172.16- 172.31 * IP Range : 172.16.0.0 - 172.31.255.255 1.05 million IP addresses (16*256*256)

Class A Private IP address range

* Starting Value : 10 * IP Range : 10.0.0.0 - 10.255.255.255 - 256 * 256 * 256. = 16.7 million IP addresses that anyone can use.

DHCP

* Step 1: Discover : Client to DHCP Server - Find all of the available DHCP Servers * Step 2 : Offer - DHCP Server to client - Send some IP address options to client * Step 3 : Request - Client to DHCP Server - Client chooses an offer and makes a formal request * Step 4 : Acknowledgement: DHCP server to client - DHCP Server sends an acknowledgement to the client To remember this , think of the mnemonic of DORA the explorer.

DHCP ( Discover , offer , Request , Acknowledgement )

* Step 1: Discover : Client to DHCP Server - Find all of the available DHCP Servers * Step 2 : Offer - DHCP Server to client - Send some IP address options to client * Step 3 : Request - Client to DHCP Server - Client chooses an offer and makes a formal request * Step 4 : Acknowledgement: DHCP server to client - DHCP Server sends an acknowledgement to the client To remember this , think of the mnemonic of DORA the explorer. *DHCP gets four key pieces of information - IP address - Subnet mask - Default gateway IP - DNS server IP

110 Block

* Supports high speed data networks for Cat 5 and above and includes the use of insulation displacement contract connectors * Used almost exclusively in American-style networks and patch panels both for voice and data applications * 110 block is an improved version of the 66 block

Crossover Cable

* Swaps the send and receive pins on the other end of the cable when the connector and its pinout are created. DCE to DCE DTE to DTE * A switch to a switch connection requires a crossover cable

Network Time Protocol

* Synchronizes clocks between systems communicating over a packet-switched , variable-latency data network * Switches , routers , firewalls , servers ,workstations - Every device has its own clock * Synchronizing the clock becomes critical - Log files , authentication information , outage details * Automatic updates - No flashing 12:00 lights * Flexible - You control how clocks are updated * Very accurate - Accuracy is better than 1 millisecond on a local network UDP /port 123

Network Time Protocol (NTP)

* Synchronizes clocks between systems communicating over a packet-switched variable latency data network

1.6 DHCP renewal

* T1 Timer - Check in with the lending DHCP Server to renew the IP address *T2 timer - If the original DHCP server is down , try rebinding with any DHCP server - 87.5 % of the lease time (7/8ths)

1.5 Port Numbers

* TCP and UDP ports can be any number between 0 and 65,535 * Most servers ( services) use non-ephemeral ( non-temporary ) port numbers - This isn't always the case - its just a number * Port numbers are for communication , not security * Service port numbers need to be "well known" * TCP port numbers are the same as UDP port numbers

Subnetting

* Taking a large network and splitting it up into smaller networks *Subnet masks modify subnets and create better scoped networks 10.0.0.0/8 (16.7 million ) 10.0.0.0/24 (256s IP) * Efficiency - Allow us to create VLANS in subnets *Security - Allow separation of our networks for better security * Bandwidth - Better bandwidth control

Time to Live (TTL)

* Tells the DNS resolver how long to cache a query before requesting a new one

1.5 Ephemeral ports

* Temporary port numbers - Ports 1,024 through 65,535 - Determined in real-time by the clients

1.7 Core (Network Architecture )

* The "center" of the network * Web servers , databases , applications * Many people need access to this

Layer 4: Transport Layer

* The "post office " layer ( Parcels and letters ) * TCP ( Transmission Control Protocol) and UDP ( UserDatagram Protocol ) *TCP uses segments, while UDP uses datagrams.

1.1 Layer 3: Network Layer

* The "routing " layer * Internet Protocol ( IP) * Fragments frames to traverse different networks * Forwards traffic (routing) with logical address * IP address is either going to be IPv4 or IPv6 *IP address is the most common protocol but it's not the only protocol ( Apple Talk , Internetwork Packet Exchange) * This layer has two main functions . - One is breaking up segments into network packets and reassembling the packets on the receiving end. - The other is routing packets by discovering the best path across a physical network. * The network layer uses network addresses (typically Internet Protocol addresses ) to route packets to a destination node. * Decides which physical path the data will take

1.1 Layer 7 : Application Layer

* The application layer is used by end-user software such as web browsers and email clients. * It provides protocols that allow software to send and receive information and present meaningful data to users. * Human computer interaction layer , where applications can access the network services. * Provides application-level services where users communicate with the computer * Email applications (POP3,IMAP, SMTP) * Web browsing ( HTTP or HTTPS) * Domain Name Service * File Transfer Protocol -( FTP , FTPS and SFTP) * Remote Access - ( TELNET , SSH and SNMP)

RST (Reset) [TCP]

* Used when a client or server receives a packet that it was not expecting during the current connection.

1.1 Layer 2 - Data Link Layer

* The data link layer establishes and terminates a connection between two physically-connected nodes on a network. - It breaks up packets into frames and sends them from source to destination. *This layer is composed of two parts - Logical Link Control - which identifies network protocols ,performs error checking and synchronizes frames - Media Access Control : which uses MAC addresses to connect devices and define permissions to transmit and receive data • Packages data into frames and transmits those frames on the network * View devices logically

1.6 Resource Records

* The database records of domain name services. * Over 30 record types -IP addresses , certificates , host alias names ,etc

Classful Mask

* The default mask for a given class of IP addresses

TCP flags

* The header describes or id entifies the payload ( Here's what you're about to see ) * The TCP header contains important control information - Includes a set of bits called TCP flags * The flags control the payload - SYN - Synchronize sequence numbers - PSH - Push the data to the application without buffering - RST - Reset the connection - FIN - Last packet from the sender

1.3 Ethernet

* The most popular networking technology in the world - Standard , common , nearly universal * Many different types of Ethernet -Speeds , cabling , connectors , equipment * Modern Ethernet uses twisted pair copper of fiber *BASE (baseband) - Single frequency using the entire medium - Broadband uses many frequencies , sharing the medium

1.2 WAN Termination

* The point where you connect with the outside world - WAN provider - Internet Service Provider - The demarc * Used everywhere ( Even at home ) * Central location in a building - Usually a network interface device - Can be simple as an RJ-45 connection * You connect your CPE - Customer premises equipment or " customer prem "

1.1 Encapsulation

* The process of putting headers (and trailers) around some data * Encapsulation marks where a packet, or unit of data, beginterm-28s and ends. * The beginning part of a packet is called the header, and the end of a packet is called the trailer. * The data between the header and trailer is sometimes referred to as the payload. * Moving down layers 7 to 1 is encapsulating the data

Quality of Service (QoS)

* The purpose of QOS - To categorize traffic , apply a policy , and prioritize them in accordance with a QoS policy. * Enables strategic optimization of network performance based on different types of traffic. * We can optimize our network to efficiently utilize all the bandwidth at the right time to deliver the right service to our users and give a success and cost savings * Forwards traffic based on priority markings.

Second-Level Domains (DNS server hierarchy)

* The second-level domain is often thought of as the "name of the domain" . The top-level domain , which is an extension such ".com" is fairly generic. * The second-level domain is where domain holders put the brand name , project name, organization name or other familiar identifier for users

Transport Layer (Layer 4)

* The transport layer takes data transferred in the session layer and breaks it into "segments'" on the transmitting end. *It is responsible for reassembling the segments on the receiving end, turning it back into data that can be used by the session layer * The transport layer carries out flow control , sending data at a rate that matches the connection speed of the receiving device and error control , checking if data was received incorrectly and if not requesting it again. * Transmits data using transmission protocols including TCP and UDP

1.8 VM escape protection

* The virtual machine is self-contained - There's no way out - Or is there ? * Virtual machine escape - Break out the VM and interact with the host operating system or hardware - Once you escape the VM , you have great control - Control the host and control other guest VMs * This would be a huge exploit - Full control of the virtual woterm-523rld

Celluar ( Wireless WAN Connections)

* There are a wide range of cellular technologies in use - 2G ,3G,4G, LTE and 5G -- The G refers to the generation of cellular technology being used.

DNS records

* There are many different types of DNS records that exist within a DNS server . -A records -AAAA records - CNAME records -MX records - SOA records - PTR records -TXT records -SRV records -NS records

(Root )DNS server hierarchy

* These servers contain the global list of all the top-level domains , things like .com ,.net, .org , .mil and others

1.3 Lucent connector

* This is a newer and smaller version of an SC connector. * Like the SC connector, it does use a stick and click connection to the jack. Now to remember the LC connector, instead of the SC connector, I like to call this the love connector. * This is because you're almost always going to find the LC connector with its transmit and receive sides attached side-by-side, like lovers.

Packet reordering

* This is important as it allows us to take a big chunk of data , and cut it up into little pieces of packets * Then you can send all those packets off in different directions to get to their final destination. * The problem is sometimes these packets are going to arrive at the destination in the wrong order . - So packet reordering allows them to get all this data at the end destination at the receiver . Then they can order them correctly. * The benefit here is that because of routing each packet gets numbered and sequenced , and so if they get to the other end out of order , we can put them back into the right order and read them as a coherent message

Layer 5 : Session Layer

* This layer creates communication channels called sessions between devices. - It is responsible for opening sessions , ensuring they remain open and functional while data is being transferred and closing them when communication ends. * The session layer can also set checkpoints during a data transfer - if the session is interrupted , devices can resume data transfer from the last checkpoint. *Maintains connections and is responsible for controlling ports and sessions. * Communication management between devices ( Start, stop ,restart) * Half-duplex , full duplex * Control protocols , tunneling protocols * Keep conversations separate to prevent intermingling of data * Set up * Maintain * Tear Down

Virtualization

*Allows multiple virtual instances to exist on a single physical server *Cost savings * Consolidated servers *Increased bandwidth

Layer 1 - Physical Layer

* This layer is responsible for the physical cable or wireless connection between network nodes. It defines the connector , the electrical cable or wireless technology connecting the devices and is responsible for transmission of the raw data , which is simply a series of 0s and 1s , which taking care of bit rate control. ]* * Layer 1 devices view networks from a physical topology perspective *Use two standards in our network - TIA/EIA-568A - TIA/EIA-568B -- These standards are important as they tell whether we are using crossover cables or straight-thru cables. This is the physics of the network - Signaling , cabling , connectors - Fix your cabling , punchdowns , etc - Run loopback tests , test/replace cables , swap adapter cards

1.1 Layer 6 : Presentation Layer

* This layer prepares data for the application layer. It defines how two devices should encode ,encrypt and compress data so it is received correctly on the other end. * The presentation layer takes any data transmitted by the application layers and prepares it for transmission over the session layer. * Ensures data is in a usable format and is where data encryption occurs. * Formats the data to be exchanged and secures that data with proper encryption * Data formatting * Encryption * Character encoding * Application encryption * Often combined with Application Layer Encoding and encryption ( SSL /TLS) * Establishes the way in which information is presented, typically for display or printing. * This layer translates information in a way that the application layer understands.

Address Translation

* Three types of Address Translation -DNAT - SNAT - PAT

1.7 Traffic flows

* Traffic flows within a data center - Important to know where traffic starts and ends *East-west - Traffic between devices in the same data center * North- South Traffic - Ingress/egress to an outside device - A different security posture than east-west traffic

Traffic Shaping

* Traffic shaping is bandwidth management technique that delays the flow of certain types of network packets in order to ensure network performance for higher priority applications. - It is primarily used to ensure a high quality of service for business-related network traffic. * Traffic shaping , packet shaping * Control by bandwidth usage or data rates * Set important applications to have higher priorities than other apps * Manage the Quality of Service (QoS) - Routers ,switches ,firewalls , QoS devices

North-South Traffic (Traffic flows in Data Center)

* Traffic that enters or leaves the data center from a system physically residing outside the datacenter. * North Traffic is traffic leaving your datacenter , while South Traffic is traffic entering your data center. * In both cases , this data is exiting or entering the data center going through a firewall or other network infrastructure boundary device such as a router. * North-South traffic typically contains communications such as database queries , commands, or data submissions being sent and received. - The public and private nature of these communications make them untrusted and therefore the security of the private networks relies on firewalls and network monitoring at the perimeter.

Maintain a Session ( Session Layer )

* Transfer Data * Reestablish connection * Acknowledge receipt

Maintain a session ( Session Layer)

* Transfer data * Reestablish connection *Acknowledge receipt * Student asks a question , you go back and forth with the student . *If there is a break in the connection , you can reestablish the connection. - I didn't hear you Johnny . Can you repeat your question?

1.6 Domain Name System (DNS)

* Translates human - readable names into computer-readable IP address * Converts domain names to IP addresses using a hierarchical and decentralized system of naming. * Operates over UDP and TCP using port 53 * Hierarchical - Follow the path * Distributed database - Many DNS Servers - 13 root server clusters ( over 1,000 actual servers) ' - Hundreds of generic top-levels (gTLDs) ** .com , .org , . net ,etc - Over 275 country code top-level domains (ccTLDs) ** .us , .ca , .uk

1.3 Optical Fiber

* Transmission by light - The visible spectrum * No RF signal - Very difficult to monitor or tap * Signal slow to degrade - Transmission over long distances * Immune to radio interference - There's no RF

Transmitting Data

* Transmission units - A different group of data at different OSI layers * Ethernet operates on a frame of data ( It doesn't care whats inside ) * IP operates on a packet of data - Inside is TCP or UDP , but IP doesn't really care *TCP or UDP - TCP segment - UDP datagram

1.3 Transceiver

* Transmitter and receiver - Usually in a simple component * Provides a modular interface - Add the transceiver that matches your network

1.4 Teredo /Miredo

* Tunnel IPv6 through NATed IPv4 * End-to-end IPv6 through an IPv4 network * No special IPv6 router needed * Temporary use - We"ll have IPv6 native networks soon * Miredo - Open source Teredo for Linux * BSD , Unix and Mac OS X - Full functionality

1.3 Twinaxial cables

* Two inner conductors ( Twins ) *Common on 10 Gigabit Ethernet SFP+ cables - Full duplex , five meters , low cost , low latency compared to twisted pair * Similar to coaxial cable but uses two inner conductors to carry the data instead of just one. * Used for very short range , high speed connections between devices .

Traffic flows

* Two main types of traffic flows in our datacenter: + North-South + East-West

1.3 Coaxial Cables

* Two or more forms share a common axis * RG-6 used in television / digital cable - And high-speed Internet over Cable * RG-59 - Used to carry composite video between two nearby devices or connect an outlet to a cable modem.

Unshielded and shielded cable

* UTP ( Unshielded Twisted Pair ) - No additional shielding - The most common twisted pair cabling * STP ( Shielded Twisted Pair) - Additional shielding protects against interference - Shield each pair and / or the overall cable - Requires the cable to be grounded *Abbreviations - U = Unshielded - S = Braided shielding - F = Foil shielding * ( Overall cable )/ (individual pair s) TP - Braided shielding around the entire cable and foil around the pairs is S/FTP - Foil around the cable and no shielding around the pairs is F/UTP * STP and UTP operate about the same * Both can go about 100m

Application Services

* Unites communicating components from more than one network application

Neighbor Discovery Protocol (NDP)

* Use to learn the layer 2 addresses that are on a given network * Used to perform -router solicitation - Looking for routers on the network - router advertisement- The router makes an advertisement that its on the network. -neighbor solicitation is sent by a node to determine the link-layer address of a neighbor - neighbor advertisement - Neighbor advertisement is like router advertisement but it happens with your neighbors -redirection - informs the host that there better first-hop router options out there to increase the efficiencies of your network

Generic Routing Encapsulation (GRE)

* Used as a simple and effective way to create a tunnel , called a GRE tunnel , over a public network. * GRE tunnel does not provide any encryption

GRE (Generic Routing Encapsulation)

* Used as a simple and effective way to create a tunnel , over a public network * Tunneling protocol developed by Cisco to encapsulate a wide variety of network layer protocols inside a virtual point to point to multi-point link over the internet protocol link. * GRE tunnel does not provide any encryption

Single Mode Fiber (SMF)

* Used for longer distances and has smaller core size which allows for only a single mode of travel for the light signal. * SMF's core size is 8.3- 10 in diameter. - Smaller core size allows for a more precise signal transmission over a longer distance because it force the light to travel along a single path down the center of that cable without being dispersed around. * Can reach distances of up to 40 kilometers * More expensive than Multimode Fiber * Yellow Sheath is Single-Mode Fiber

Multimode Fiber (MMF)

* Used for shorter distances and has larger core size which allows for multiple modes of travel for the light signal *MMF's core size is 50-100 microns in diameter - 6 to 10x times larger than a single mode fiber's core * Up to 2kms or less *Less expensive than SMF * Aqua blue or orange sheath means its an multimode fiber

Ring

* Used in many popular topologies - Uses a cable running in a circular loop where each device connects to the ring but data travels in a singular direction Token Ring - Ring topology that uses an electronic token to prevent collisions when communicating on the network - Only one will talk or there will be a collision any Metro Area Networks ( MANs) and Wide Area Networks ( WANs) - Dual-rings - Built in fault tolerance On the exam ring = redundancy or FDDI

66 Block (M Block)

* Used in older analog telephone systems and older cat 3 networks and supports a 25 pair cable that would run to the MDF or IDF * Only going to see 66 block in the MDF or IDFs when they're being used to terminate traditional analog phone lines

Port Mirroring

* Used on a network switch or a router to send a copy of network packets seen on one switch port (or an entire VLAN) to a network monitoring connection on another switch port. * This is commonly used for network appliances that require monitoring of network traffic.

Internet Control Message Protocol

* Used to communicate information about network connectivity issues back to the sender. * An example of ICMP is ping. * ICMP is used to send ICMP datagrams from a client, a server or network device to indicate whenever there's a problem with network connectivity, by sending redirect messages, echo, and echo replies and other diagnostic messages.

Internet Control Message Protocol (ICMP)

* Used to communicate information about network connectivity issues back to the sender. Ex. Ping * Used as an error reporting mechanism and query service. * ICMP is used to send ICMP datagrams from a client , server or network device to indicate whenever there is a problem with network connectivity by sending redirect messages , echo , and echo replies and other diagnostic messages.

Access/Edge

* Used to connect to all of your endpoint devices like your computers , laptops ,servers , printers , access points and everything else. * These access or edge devices are going to usually be regular switches, and they're going to be used to ensure packets are being converted to frames and delivered to the correct end point devices when needed.

DHCP v6

* Used to delegate IPv6 prefixes and to allocate IPv6 Addresses.

RFC 1918

* Used to document how organizations could conduct address allocation for private Internets (Intranets)

PSH (Push )[TCP flags]

* Used to ensure data is given priority and is processed at the sending or receiving ends

PSH flag ( push )

* Used to ensure data is given priority and is processed at the sending or receiving ends

Management Plane (SDN)

* Used to monitor traffic conditions and the status of the network.

IPSec (Internet Protocol Security)

* Used to protect one or more data flows between peers * Is a TCP protocol that authenticates and encrypts IP packets very effectively. * Data confidentiality * Data integrity * Origin authentication *Anti-replay * IPSec lets you encrypt your tunnel to protect data from prying eyes. *Used heavily in VPNs * Uses two underlying protocols - Authentication Header - Encapsulating Security Payload

Internet Protocol Security (IPSec)

* Used to protect one or more data flows between peers * Now, IPsec is a TCP protocol that authenticates and encrypts IP packets very effectively securing those communications between computers and devices *By using IPsec, you can enable data confidentiality, integrity, origin authentication, and anti-replay. *IPsec is going to allow you to create a tunnel over a public wide area network, just like a GRE tunnel does, but IPsec also lets you encrypt that tunnel to protect your data from prying eyes. *IPSec uses two underlying protocols , authentication headers or AH and encapsulating security payloads or ESPs.

Encryption ( Layer 6)

* Used to scramble the data in transit to keep it secure from prying eyes and provide data confidentiality * This is going to provide us with confidentiality of our data as it crosses our network and as it's stored. - Ex . TLS ( Transport Layer Security )

SYN ( Synchronization)

* Used to synchronize connection during the three-way handshake

SYN (Synchronization) [TCP Flags ]

* Used to synchronize connection during the three-way handshake

Automatic Private IP Addressing (APIPA)

* Used when a device does not have a static IP address or cannot reach a DHCP server * Allows for the quick configuration of a LAN without the need for a DHCP server *APIPA-assigned devices cannot communicate outside the LAN with non-APIPA devices

APIPA (Automatic Private IP Addressing)

* Used when a device does not have a static IP address or cannot reach a DHCP server * Range from 169.254.0.0 to 169.254.255.255

1.2 Network Topologies

* Useful in planning a new network - Physical layout of a building or campus * Assists in understanding signal flow ( Troubleshooting problems )term-66

Forward Lookup

* Uses DNS to find the IP address for a given domain name

Cable Modems

* Uses a cable television infrastructure that is made up of a hybrid fiber-coax (HFC) distribution network * Cable modems transmit and receive over cable television infrastructure *Remember when talking about HFC or DOCSIS (Data over Cable Service Interface Specification we are talking about cable modems

PIM Sparse Mode (PIM-SM)

* Uses a shared distribution tree and creates an optimal distribution tree through shortest path tree (SPT) switchover

Bus

* Uses a single cable where each device taps into by using a vampire tap or a T-connector

Infrastructure Mode

* Uses a wireless access point as a centralized point and supports wireless security controls -The most common wireless communication mode

Radio Frequency Identification (RFID)

* Uses electromagnetic fields to read data stored in embedded tags.

Fiber Optic Cable

* Uses light from a light-emitting diode (LED) or laser to transmit information through a thin glass fiber * Greater usable range * Greater data capacity *Expensive * Difficult to work with and requires special tools and training to learn how to make those fiber cables , or to repair broken fiber cables.

PIM-DM : Flooding

* Uses source distribution tree (SDT) to form an optimal path between source router and last hop router. Before the optimal path is formed , entire network is initially flooded and consumes unnecessary bandwidth.

Control Layer (SDN)

* Uses the information from the applications and decides how to route a data packet on the network. * It also makes decisions about how traffic should be prioritized , how it should be secured , and where it should be forwarded to.

1.8 Connecting to the cloud

* VPN - Site-to-site virtual private network - Encrypt through the Internet * Virtual Private Cloud Gateway - Connect users on the Internet * VPC Endpoint - Direct connection between cloud provider networks

contention-based Model

* Very chaotic and can transmit whenever possible * Contention-based access is chaotic and can cause collisions * Ethernet uses contention-based network access

* 1.4 Magic Number subnetting

* Very straightforward method - Can often perform the math in your head * Subnet with minimal math - Still some counting involved * Some charts might help - But may not be required - CIDR to Decimal - Host ranges

WAN technology with Available Bandwidth

* Wan Technology : Frame Relay Typical Available Bandwidth : 56 Kbps - 1.544 Mbps * Wan Technology :T1 Typical Available Bandwidth : 1.544 Mbps Wan Technology : T3 Typical Available Bandwidth : 44.736 Mbps Wan Technology : E1 Typical Available Bandwidth : 2.048 Mbps Wan Technology : E3 Typical Available Bandwidth : 34.4 Mbps Wan Technology : ATM Typical Available Bandwidth : 155 Mbps - 622 Mbps Wan Technology : SONET Typical Available Bandwidth : 51.84 Mbps - 159.25 Gbps

DNS continued

* When DNS is conducting a domain name query or lookup , its going to use UDP to accept that request from a client and then send the response from that server back. * But if DNS is going to be doing a zone transfer between two different servers , its going to use TCP for that.

Comparing Copper vs Fiber

* When comparing copper vs fiber there are four areas to compare : - Speed of bandwidth - Distance covered - Electromagnetic interference immunity - Security * Fiber optic cables can go at least 40 kms and can carry speeds of 60 or 70 Tbps or more - Fiber is used when you want to cover a really long distance * Copper cables can only go up to 100 meters and can carry speeds up to 10 Gbps * If you are in an LAN , you would want to use copper , while if you are in a MAN ,or WAN you might want to use fiber.

Internet Layer

* Where data is taken and packaged into IP datagrams - This is where we take data and package it into those IP datagrams. - This contains your source and destination IPs and you are going to forward those datagrams between different hosts across the networks. * Some examples of Internet Layer include IP, IMP , ARP , and reverse ARP

Internet Layer (TCP/IP)

* Where data is taken and packaged into IP datagrams *IP * ICMP *ARP *Reverse ARPterm-63

Demarcation Point

* Where the Internet Service Providers connection ends and your network begins

1.7 Access (Network Architecture)

* Where the users connect * End stations , printers

110 block

* Wire-to-Wire patch panel - No intermediate interface required * Replaces the 66 block - Patch Category 5 and Category 6 cables * Wires are "punched " into the block - Connecting block is on top * Additional wires punched into connecting block - Patch the top to the bottom * Supports high speed data networks for CAT 5 and above and includes the use of insulation displacement contract connectors * One of the most common punch down blocks

Packet-Switched Connection

* Works like an always- on dedicated lease line, but multiple customers share the bandwidth.

1.8 Hybrid Cloud Deployment Model

* a mix of public and private

1.6 External DNS

*Often managed by a third-party * Does not have internal device information *Google DNS, Quad 9

Distributed switch

* acts as a single switch across all associated hosts in a data center and provides centralized provisioning , administration and monitoring of virtual networks. - Virtual switch configured for an entire datacenter - Can have up to 2,000 hosts - Consistent configuration across all hosts - Must have Enterprise license or belong to vSAN cluster

Link Local

* is the IP address that is to be use for communication within a logical division of the network or in the broadcast domain to which the host is connected.

Circuit Switching

* this is where we want to have the same path each and every time. * Dedicated communication link is established between two devices

1.3 Copper Cable Categories

** Ethernet Standard - Cable Category - Maximum Supported Distance Category 5 - 1000BASE-T, 100 meters Category 5e (enhanced) - 1000BASE-T , 100 meters Category 6 - 10GBASE-T - 37 to 55 meters ( Unshielded ) - 100 meters ( shielded ) Category 6A (augmented) -10GBASE-T - 100 meters Category 7 ( shielded only ) , 10GBASE-T , 100 meters Category 8 ( shielded only ) , 40GBASE-T , 30 meters

1.3 10 and 100 megabit Ethernet

*10 BASE-T (twisted pair ) - Two pair , Category 3 cable minimum - 100 meter maximum distance * 10 BASE-T allows up to 10 Mbps of speed but only covers a distance of up to 100 meters. *100BASE-TX -"Fast Ethernet " - Category 5 or better twisted pair copper - two pair - 100 meters maximum length

1.3 10GBASE-T

*10 Gig Ethernet over copper - 4 pair balanced twisted pair * Frequency use of 500 MHz - Well above the 125 MHz for gigabit Ethernet *Category 6 -Unshielded : 55 meters - Shielded :100 meters * Category 6A ( augmented ) - Unshielded or shielded : 100 meters

IPV4

*10.1.2.3 *192.168.1.4 - The example * As you can see, each IPv4 address is made up of four parts to form that address. This is known as a dotted-decimal notation. When you're referring to each of those four individual parts, we call this an octet because they each have a decimal number that's used to represent an 8-bit number. * Because these decimal numbers represent an 8-bit or eight binary digits, this means that they can only represent a value from zero to 255 in each of those four positions. Now, when all four octets are combined, we have four octets that contain eight bits each, for a total of 32 bits of total addressable space when using an IPv4 address.

IPv4

*10.1.2.3 *192.168.1.4 - The example * As you can see, each IPv4 address is made up of four parts to form that address. This is known as a dotted-decimal notation. When you're referring to each of those four individual parts, we call this an octet because they each have a decimal number that's used to represent an 8-bit number. * Because these decimal numbers represent an 8-bit or eight binary digits, this means that they can only represent a value from zero to 255 in each of those four positions. Now, when all four octets are combined, we have four octets that contain eight bits each, for a total of 32 bits of total addressable space when using an IPv4 address.

1.3 Gigabit Ethernet over fiber

*1000BASE-SX - Gigabit Ethernet using NIR (near infrared ) light - Usually over multi-mode fiber - 220 meters to 500 meters , depending on fiber type * 1000BASE-LX - Gigabit Ethernet using long wavelength laser - Multimode fiber to 550 meters - Single-mode fiber to 5 km

Cat 5e (Gigabit Ethernet)

*1000BASE-T *1000 Mbps (1 gbps) * 100 meters

1.3 100 megabit Ethernet over fiber

*100BASE-FX - Pair of multimode fiber - Same fiber as FDDI -Laser components - 400 meters (half-duplex) 2 kilometers (full-duplex ) * 100BASE-SX - A less expensive version of 100 megabit Ethernet over fiber - LED optics , 300 meters maximum distance

Cat 5 (Fast Ethernet)

*100BASE-TX * 100 Mbps * 100 meters

Cat 7

*10GBASE-T *10 Gbps *100 meters

Class D IP Address

*1st octet value : - 224 -339 * Doesn't have an subnet mask assigned to it. * Class D addresses are special and they're reserved for multicasting or multicast routing.

Cat 8

*40GBASE-T *40 Gbps *30 meters

WLAN (wireless LAN)

*802.11 Technologies * Mobility within a building or geographic area * Expand coverage with additional access points

On-Premise Data Center

*A traditional , private data infrastructure usually located in the same building as the main offices.

Channel Service Unit/Data Service Unit (CSU/DSU)

*Acts as a digital modem that terminates a digital circuit at the customer's location(for example, a T1 or an E1 circuit). *T1 and E1's are dedicated lease lines and they CSU/DSUs to connect to your network * A channel service unit/data service unit (CSU/DSU) device is designed to connect a terminal device to a T1 line. The terminal device or Data Terminal Equipment (DTE), such as a router, will connect to the T1 line via CSU/DSU (Channel Service Unit/Data Service Unit). A CSU/DSU (Channel Service Unit/Data Service Unit) is a hardware device about the size of an external modem that converts digital data frames from the communications technology used on a local area network (LAN) into frames appropriate to a wide-area network (WAN) and vice versa.

Horizontal Scaling (Scaling Out)

*Adding additional resources to help the extra load being experienced * Scaling out provides more redundancy and results in less downtime *Elasticity

(Text) TXT records [DNS]

*Adds text into the DNS * Typically carries machine-readable data such as opportunistic encryption , sender policy framework , DKIM , DMARC - Most of the time , you are going to see text records to prove domain ownership through adding some machine-readable code and to provide email spam prevention

Multitenancy

*Allowing customers to share computing resources in a public or private cloud

Windowing (Transport Layer )

*Allows the clients to adjust the amount of data in each segment - If you're sending data and getting a lot of retransmissions ,you might be sending too much information. So you might need to back it down and the close the window a little bit. If you're not getting any retransmissions , it means you're probably not going fast enough and might need to open the window up.

Datacenter

*Any facility that businesses and other organizations use to organize, process ,store and disseminate large amounts of data

Elasticity

*Attempts to match the resources allocated with the actual amount of resources needed at any given point in time. *With Elasticity ,our Cloud-based servers and networks can grow or shrink dynamically as they need to in order to adapt to a changing workload. * Short-term addition or subtraction of resources * Often used in public Cloud services . Example AWS (Amazon Web Services)

Dynamic NAT (DNAT)

*Automatically assigns an IP address from a pool and gives a one-to-one translation. * The way dynamic NAT would work, is when you want to get online, your computer, would go to the router, it would borrow one of these five IP addresses, it would do a translation from your private IP to your public IP and that way you'd be able to use it. Go online, make the request and then when you're done, your computer turned that public IP, back into the router, back to the shared pool. This way you can maximize your public IP space for the most amount of internal clients. And it did all of this dynamically and you didn't have to worry about it.

Top-Level Domains (DNS server hierarchy)

*Broken up into two categories . - Organizational hierarchies such as .com, .net , .org and others - Geographical hierarchy -- .uk for the United Kingdom -- .fr for France -- .it for Italy and other countries like that.

1.2 Satellite networking

*Communication to a satellite - Non terrestrial communication * High cost relative to terrestrial networking - 50 Mbit/s down , 3 Mbit/s up are common - Remote sites , difficult-to-network sites * High latency -250 ms up , 250 ms down * High frequencies -2 GHz - Line of sight , rain fade

Circuit-Switched Connection

*Connection is brought up only when needed, similar to making a phone call

User Datagram Protocol (UDP)

*Connectionless protocol that is an unreliable way to transport segments across the network. * If dropped sender is unaware. * Is good for audio and visual streaming * Can increase the performance of your network because you're going to have zero retransmissions * Detects if packets are corrupted when they are received by a client using a checksum *Unreliable *Connectionless *No windowing or retransmission *No sequencing * No acknowledgment

CAN (Campus Area Network)

*Connects LANs that are building-centric across a university , industrial park or business park.

Backbone Switch

*Connects to everything on the network

Domain Name System (DNS)

*Converts the domain names used by a website to the IP address of its server.

Pointer record (PTR) [DNS]

*Correlates an IP address with a domain name . * So if a user is trying to determine if a domain name is going to be used for a given IP , that query can made against the Pointer records instead of the A records. - This lets you go from an IP address to a domain name. * Helpful if you're trying to prove your domain is not associated with spam * When you store an IP address in a Pointer Record , its going to be reserved and have in-addr.arpa added to it at the end.

Loopback address

*Creates a loopback to the host and is often used in troubleshooting and testing network protocols on a system * An address that sends outgoing signals back to the same computer for testing. In a TCP/IP network, the loopback IP address is 127.0.0.1, and pinging this address will always return a reply unless the firewall prevents it. - The loopback address allows a network administrator to treat the local machine as if it were a remote machine

Recursive Lookup

*DNS server communicates with several other DNS servers to hunt down the IP address and return to the client

anycast address

*Data travels from a single source device to the device nearest to multiple ( but specific) destination devices *Used to identify a set of interfaces so that a packet can be sent to any member of a set

Network Attached Storage (NAS)

*Disk storage delivered as a service over TCP/IP

Frequency Division Multiplexing (FDM)

*Divides the medium into channels based on frequencies and each session is transmitted over a different channel

Statistical Time-Division Multiplexing (StatTDM)

*Dynamically allocates the time slots on an as-needed basis

Stratum (NTP)

*Each of layer of the NTP hierarchy is known as a stratum. *Stratum 0 is the most precise timekeeping devices we have access to . - Includes things like the atomic clock , GPS - Stratum 0 is also known as reference clocks - Important to note that the NTP server itself cannot be considered at Stratum 0, only the reference clocks can . *Stratum 1 is actually where the first NTP servers are in the NTP hierarchy. - This is where any computer whose time source is synchronized to within a few microseconds of an attached Stratum 0 device. - These Stratum 1 servers are known as primary time servers. * Stratum 2 is connected to a synchronized Stratum 1 server. - Often a Stratum 2 server is configured to query multiple Stratum 1 servers to ensure it has a stable and robust time source to provide the other devices within its peer group. * Stratum 3 servers are synchronized upward to Stratum 2 servers. * This patterns continues to Stratum 5 and so on. * Each time , we add a little bit more delay and things become a little bit further from Stratum 0 with the precise time that we started with. * NTP can handle a maximum of 15 stratum levels

Infrastructure as Code (IAC)

*Enables managing and provision of infrastructure through code instead of through manual processes * Infrastructure can be referred to as Virtual machines , virtual devices * To use infrastructure as code ,effectively , we need to also use scripted automation and orchestration * Three key areas in IAC - Scripting - Security Templates - Policies

Application Services ( Layer 7 )

*Unites communicating components from more than one network application

1.2 Hypervisor

*Enables virtualization to occur and emulates the physical hardware * A hardware ,software , or firmware capable of creating virtual machines and then managing and allocating resources to them. * Virtual Machine Manager - Manages the virtual platform and guest Operating Systems * Hardware management - CPU , networking , security * Single console control (One pane of glass )

1.2 Copper

*Extensive installations - Relatively inexpensive - Easy to install and maintain * Limited bandwidth availability - Physics limit electrical signals through copper * Wide area networks - Cable modem , DSL , T1 , T3 local loop * Often combined with fiber - Copper on the local loop , fiber in the backbone

1.3 APC ( Angle-polished connectors)

*Ferrule end-face radius polished at an 8 degree angle * Lower return loss , generally higher insertion loss than UPC * This angled face means that the reflected light is going to reflect at an angle into the clouding of the cable , instead of straight back down towards the source of light. This provides a better overall signal with less noise. * In general , you going to see SC connectors like to use APC more. * If the connector is green its APC.

1.6 Lookups

*Forward Lookup - Provide the DNS server with a FQDN - DNS server provides an IP address

IP Helper

*Forwards several different kinds of UDP broadcasts across the router and can be used in conjunction with the DHCP relay.

2G

*Frequency : 1800 Mhz *Speed : 14.4-64 Kbps * 2G devices communicate over a GSM network . * Ran over a digital network that use multiplexing and therefore it was able to start using data in addition to just providing phone calls. * Was the first to have SMS and text messaging as well as the ability to do international roaming * Also so the evolution of EDGE (Enhanced Data Rates for GSM evolution ). - This brought our speeds up to about 1 Mbps for most modern 2G devices.

1.3 1000BASE-T

*Gigabit Ethernet over Category 5 - 4 pair balanced twisted-pair * Category 5 - Category 5 is deprecated , so we Cat 5e today - A shift to using all four pair - 100 meter maximum distance

Scalability

*Handles the growing workload required to maintain good performance and efficiency for a given software or application. * Designing to be more of a static or long-term solution.

Domain Name System ((DNS))

*Helps network clients find a website using human-readable hostnames instead of numeric IP addresses

1.4 Finding Router

*ICMPv6 adds the Neighbor Discovery Protocol * Routers also send unsolicited RA messages - From the multicast destination of ff02::1 *Transfers IPv6 address information , prefix value , and prefix length , etc - Sent as a multicast *Neighbor Advertisement (NA)

1.4 DHCP

*IPv4 address configuration used to be manual - IP address , subnet mask, gateway , DNS servers, NTP servers,etc * Dynamic Host Configuration Protocol - Provides automatic addresses and IP configuration for almost all devices.

Data Communications Equipment (DCE)

*Includes things like switches ,modems , hubs and bridges

Vertical Scaling (Scaling Up)

*Increases the power of the existing resources in the environment * Scalability

Duplex

*Known as full duplex communication where devices are able to communicate at the same time

Bidirectional (Half-duplex)

*Known as half-duplex communication where devices must take turns to communicate

Dedicated lease line

*Logical connection that connects two sites through a service provider's facility or a telephone company central office * Point-to-Point connection between two sites (Bandwidth is available all the time) * Think of it as a single pipe going directly from your service provider's office to your office and nobody can use it , but you..

Storage Area Network ( SAN)

*Looks and feels like a local storage device * Block-level access * Very efficient reading and writing * Requires a lot of bandwidth - May use an isolated network and high-speed network

Host (Dns Server Hierarchy)

*Lowest and most detailed level inside of the DNS hierarchy and refers to a specific machine or server on the network.

1.6 Internal DNS

*Managed on internal servers - Configured and maintained by the local team - Contains DNS information about internal devices - DNS service on Windows Server

Static NAT (SNAT)

*Manually assigns an IP address and gives a one-to-one translation * Can't multishare like Dynamic NAT (DNAT) * Was used as a security feature

Route Discovery and Selection

*Manually configured as a static route or dynamically through a routing protocol * Well , routers are going to maintain a routing table so , they can understand how to forward a packet basked on the destination IP where it wants to get to. * There are a lot of different ways to do this and they can do this either as an static route or dynamically-assigned route using a routing protocol like RIP , OSPF , EIGRP and many others *Routing protocols help us decide how data is going to flow across the network and how the routers are going to communicate that information.

Microsoft CHAP (MS-CHAP)

*Microsoft enhanced version of CHAP which includes a two way authentication

1.6 Configuring NTP

*NTP client - Specify the NTP server address ( IP or hostname) - Use multiple NTP servers ( if available ) for redundancy * NTP server - You need at least one clock source - Specify the stratum level of the clock - If there's a choice , the lower , the lower stratum level wins

1.2 Smartjack

*Network interface unit (NIU) - The device that determines the demarc - Network Interface Device - Telephone Network Interface *Smartjack - More than just a simple interface - Can be a circuit card in a chassis * Built-in diagnostics - Loopback tests * Alarm indicators - Configuration , status

Buffering

*Occurs when devices allocate memory to store segments if bandwidth isn't readily available

1.1 OSI Model

*Open Systems Interconnection Reference Model also referenced called OSI stack * It's a guide (thus the term "model") - Dont get wrapped up in the details * There are unique protocols at every layer * Layer 1 (Physical ) * Layer 2 ( Data Link) * Layer 3 ( Network) * Layer 4 ( Transport) * Layer 5 (Session) * Layer 6 (Presentation) * Layer 7 ( Application) * A good way to remember the layer is : - All People Seem to Need Data Processing - Please Do Not Trust Sales Person's Answers - Please Do Not Throw Sausage Pizza Away Data data data segments packets frames bits - Data is in layers 5-7 Segments in layer 4 Packets in layer 3 Frames in layer 2 Bits in layer 1 - Do some people fear birthdays

1.3 T568A and T568B termination

*Pin assignments in EIA/TIA- 568B - Eight conductor 100 ohm - balanced twisted pair- cabling * 568A and 568B are different pin assignments for 8P8C connectors * You can't terminate one of the cable with 568A and the other with 568 B -You'll run into confusion and technical problems

CNAME (Canonical name record)

*Points a domain to another domain or subdomain -CNAME records can only be used to point to another domain or subdomain , not to an IP address

1.6 Reverse DNS

*Provide the DNS Server with an IP address * The DNS Server provides an FQDN

Logical Link Control (LLC)

*Provides connection services and allows acknowledgement of receipt of messages. - So, for example, if I called up and I asked if you got my phone call, you could say yes and that would acknowledge the receipt of that and then, we can move on to the next message. Logical link control does this for our networks. - Essentially, it's going to limit the amount of data that a sender can send at once and allow the receiver to keep from being overwhelmed. LLC is the most basic form of flow control * Logical link control also gives us some basic error control functions such as allowing the receiver to inform the sender if their data frame wasn't received or if it was received corrupted and it does this by using a checksum. * Now, since everything it receives is just a series of ones and zeroes, the receiver is going to add all of these up and the last bit will either be even or odd. If it matches, they add them all up and they're even, then, it's going to assume that this was good if you have received a zero, meaning it was even. If the last bit was odd, meaning it was a one, and they added up all the numbers and they got an odd number, that means it was good, as well. But if not, they can figure that something was bad and then ask for a retransmission of the frame.

1.3 QSFP

*Quad Small Form-factor Pluggable - Up to 40 Gbps * QSFP+ is four-channel SFP+ - Up to 41.2 Gbps * QSFP28 - Up to 100 Gbps * GSFP56 - Up to 200 Gbps - Cost savings in fiber and equipment - Additional efficiency over a single fiber run

Fibre Channel over Ethernet (FCoE)

*Removes the need for specialized hardware and runs over your Ethernet networks * A storage protocol that enables Fibre Channel communications to run directly over Ethernet. * FCoE makes it possible to move Fibre Channel traffic across existing high-speed Ethernet infrastructure and converges storage and IP protocols onto a single cable transport and interface. * The goal of FCoE is to consolidate and reduce switch complexity as well as cut back on cable and interface card counts.

1.2 Network function virtualization

*Replace physical network devices with virtual version s - Manage from the hypervisor * Same functionality as a physical device - Routing , switching , load balancing , firewalls . * Quickly and easily deploy network functions - Click and deploy from hypervisor *Many different deployment options - Virtual machine, container , fault tolerance , etc.

Internet Control Message Protocol (ICMP)

*Send error messages and operational information to an IP destination. * The most common one is PING - Now, this is not a tool that's used regularly by end-user applications, but it is used by us as administrators to help troubleshoot our network and figure out what is up and what is down and what isn't working. * Another common one is traceroute - This will trace the route that a packet takes through the network and tells you every single router along the way as it goes through, essentially doing a large series of pings through each and every router so you could figure out which routes were up and which routes were down.

1.3 SFP and SFP+

*Small Form-factor Pluggable ( SFP) - Up to 4.2 Gbps - Commonly used to provide 1 Gbit/s fiber - 1 Gbit/s RJ45 SFPs also available * Enhanced Small Form-factor Pluggable (SFP+) - Exactly the same size as SFPs - Supports data rates up to 16 Gbit/s - Common with 10 Gigabit Ethernet

GBIC

*Standard hot-pluggable gigabit Ethernet transceiver that can take in copper or fiber as its connector

SOA (Start of Authority)

*Stores important information about a domain or zone - This could include things like : -- When the domain was last updated -- Email address of the administrator of the domain

Layer 4 Devices

*TCP & UDP are protocols for layer 4 *WAN accelerators *Load balancers * Firewalls

1.4 Configuring IPv6

*There's no ARP in IPv6 - So how do you find out the MAC address of a device * Neighbor Solicitation (NS) - Sent as a multicast * Neighbor Advertisement ( NA)

Security Templates

*These contain a series of configuration files that are going to applied to the different devices being deployed in your environment. *These may include network settings , access control lists ,group policies ,or permissions

Transmitting Data

*Transmission units - A different group of data at different OSI layers * Ethernet operates on a frame of data ( It doesn't care what's inside ) * IP operates on a packet of data -Inside is TCP or UDP ,but IP doesn't really care

1.5 TCP and UDP

*Transported inside of IP - Encapsulated by the IP protocol *Two ways to move data from place to place - Different features for different applications * OSI layer 4 - Transport Layer * Multiplexing - Use many different application at the same time - TCP and UDP

Nameserver (NS)[DNS)

*Type of DNS server that stores all the DNS records a given domain. - This is used to indicate which DNS name server in the world is going to be the authoritative one for that domain. - You can have a primary and backup name server

Microwave

*Uses a beam of radio waves in the microwave frequency range to transmit information between two fixed locations *In a frequency range of 300 MHz to 300 GHz - UHF (Ultra High Frequency ) - SHF (Super High Frequency) - EHF (Extremely High Frequency) *Microwave can provide you with a super fast point to point connection between two places . - But both antennas must maintain a line of sight - Normally have a limitation of 40 miles or 64 kilometers

PIM-DM (PIM Dense Mode)

*Uses periodic flood and prune behavior to form optimal distribution tree

SD-WAN - software-defined wide area network

- A WAN built for the cloud * The data center used to be in one place - The cloud has changed everything * Cloud-based applications communicate directly to the cloud - No need to hop through a central point

STP (shielded twisted pair)

- Additional shielding protects against interference - Shield each pair and / or the overall cable --- Each pair is going to be wrapped with some metal foil - Requires the cable to be grounded - More expensive * Is a type of cabling that prevent electrical interferences or cross talk.

Core Layer ( Three Tier Hierarchy)

- Core layer is going to consist of the biggest and fastest and most expensive routers that you are going to end up working with. - Core layer is considered the backbone of the network and is used to merge geographically separated networks into one logical and cohesive unit.

1.2 vSwitch (Virtual Switch )

- Move the physical switch into the virtual environment *Functionality is similar to a physical switch - Forwarding options , link aggregation , port mirroring , NetFlow *Deploy from the hypervisor - Automate with orchestration

UTP (Unshielded Twisted Pair)

- No additional shielding (No metal being used) - The most common twisted pair cabling

UDP Header

-8 bytes (64 bits) long, divided into four sections/fields: 1) source port - where data is coming from 2) destination port - where data is going 3) message length - how many bytes the total udp header is 4) checksum - provide validition that udp has been received

Things to remember (Fiber)

1. Copper Cables have a maximum distance of 100 meters 2. Using Cat 6 at 100 meters will the speed from 10 Gbps to 1 Gbps 3. Using CAT 6 at under 55 meters can reach 10 Gbps of speed 4. Multimode Fibers deal with shorter distances , something in the 200 to 500 meter ranges 5. Use single mode fiber for longer distances Remember S is not single , so if it doesnt have S in its name it doesnt use Multimode fiber

Assignable IP addresses

2^h -2 h = number of host bits /25 2^7 - 2 32 total - 25 network = 7 host * Every IP address have to have two IP address to be a network - Network ID (first one ) - Broadcast ID (last one) 192.168.1.0./24 2^0 - 1 subnet 0 = number of borrowed bits

Cat 3 (Ethernet)

10Base- T 10 Mbps 100 Meters

Punchdown Block

4 types of punchdown blocks - 66 block - 110 Block - Krone Block - BIX block Punchdown Block are located in the MDF, IDF

DB-9 or DB-25 (RS-232)

9-pin or 25-pin D-subminiature. Used for asynchronous serial communications and connecting to an external modem.

A (Address) record

A DNS record that links a hostname to an IPV4 address - Only work for IPv4 addresses.

Hypervisor Type 2

A Type 2 hypervisor is typically installed on top of an existing OS, and it's called a hosted hypervisor because it relies on the host machine's pre-existing OS to manage calls to CPU, memory, storage and network resources. Type 2 hypervisors include VMware Fusion, Oracle VM VirtualBox, Oracle VM Server for x86, Oracle Solaris Zones, Parallels and VMware Workstation.

SFP (Small Form Factor Pluggable) (Transceiver)

A smaller module than a GBIC and its a compact and hot-pluggable optical module that used with fiber connections and it could be plugged in or out of that switch or router without turning off the device. Speed: Up to 4.2 Gbps

SubDomain (Dns server hierarchy)

A subdomain is a domain that is a part of a larger domain . It is used as an easy to create a more memorable Web address for specific or unique content with a website. Ex. Pictures on Google - Images.google.com

Server

Any device that provides resources to the rest of the network * Dedicated hardware * Specialized software

Connection Services

Augment Layer 2 connection services to improve reliability

Hypervisor Type 1

Commonly known as a bare-metal, embedded, or native hypervisor. Works directly on the hardware of the host and can monitor operating systems that run above the hypervisor. The hypervisor is small, as its main task is sharing and managing hardware resources between different guest operating systems.

Uniform Resorce Locator (URL)

Contains the FQDN with the method of accessing information

Routing Metrics

Each routing protocol has its own way of calculating the best route - i.e., RIPv2, OSPF, EIGRP • Metric values are assigned by the routing protocol - RIPv2 metrics aren't useful to OSPF or EIGRP • Use metrics to choose between redundant links - * Lower metrics are preferred over higher metrics - i.e., 1 is better than 2 *Some metrics routing protocols use are - Hop Count - Believability - Reliability - Bandwidth - Delay - Cost - Other

Configuring the next Hop

Every router needs to know where traffic should be sent - Your packet is always asking for directions • A router with the incorrect next hop will result in a routing problem - Data will go the wrong direction - A routing loop is easy to create - You'll know quickly if there's a loop

1.1 IP Fragmentation

Fragments are always in multiples of 8 because of the number of fragmentation offset bits in the IP header

3G

Frequency : 1.6-2 GHz Speed : 144 Kbps to 2 Mbps *In 3G there are 3 technologies that you may find: - WCDMA ( Wideband Code Division Multiple Access -- This is used by the UTMS standard and could reach data speeds of up to 2 Mbps . This is the slowest of 3 technologies. - HSPA (High Speed Packet Access ) -- Reaches speeds of up to 14.4 Mbps and is sometimes referred to as 3.5 G - HSPA + (High Speed Packet Evolution ) -- Reaches speeds of up to 50 Mbps and is sometimes referred to as 3.75 G

4G

Frequency : 2-8 GHz Speed : 100 Mbps to 1 Gbps *4G LTE - 4G Long Term Evolution *LTE-A - Advanced version of LTE and increases speeds of two to three times of regular LTE

Layer 5 Devices

H.323 NetBIOS * H.323: Used to set up , maintain , and tear down voice and video connections ( Ex. Skype or Facetime) H.264 - These operate over the Real-Time Protocol . * Anytime you see RTP , you want to think about streaming audio or streaming video NETBIOS - Used to share files over a network

Transition Modulation (Physical Layer )

If it changes during the clock cycle , then a 1 is represented ( otherwise a 0 is represented )

100BASE-FX

MMF (multi-mode fiber) - 100Mbps, 2 km

Multicast routing

Multicast sender sends traffic to a class D IP address known as a multicast group its goal is to send the traffic only to the devices that want it

Application Layer ( TCP / IP )

OSI Layers 5. Session 6. Presentation 7. Application Dictates how programs are going to interface with the transport layer by conducting session management. Ex. HTTP , Telnet, FTP ,SSH, SNMP , DNS, SSL/TLS

10GBASE-LR

SMF 10Gbps 10kms

1000BASE-LX

SMF/MMF 1000 Mbps 5km/550 meters

Layer 2 examples

Switches , bridges and mac addresses are examples of things that are in this layer.

Routing data across the network

There are three ways for us to route data across the network * Packet switching * Circuit switching * Message switching

Switches

They are smarter than hubs , because they use logic to learn which physical ports are attached to which devices based on their MAC addresses.

Flow control

This is going to prevent the sender from sending data faster than the receiver can get it. Or it may tell you slow down , and that you are sending too much data or speed up , I can take more , and ready for more.

QSFP28 (Transceiver)

Transceiver with speeds up to 100 Gbps

QSFP56

Transceiver with speeds up to 200 Gbps

Quad small form-factor pluggable (QSFP) (Transceiver)

Transceiver with speeds up to 40 Gbps

Coarse Wavelength Division Multiplexing (CWDM)

Wavelength : Up to 18 channels Channel Distance: 20nm Speed: Up to 10Gbps (Ethernet) - Up to 15 Gbps Fiber

Dense Wavelength Division Multiplexing

Wavelength : Up to 80 channels Channel Distance: 0.8 nm Speed: Up to 8Tbps (100 Gbps/Channel)

Satellite Modems

▪ Used in remote, rural, or disconnected locations where other connections are not available ▪ Provides relatively fast speeds like a DSL modem, but contain low bandwidth usage limits and charge high costs for over limit usage ▪ Potential issues with Satellite communications: ● Delays - Time to satellite and back ( > 1 4 second) ● Weather conditions or Thunderstorms and snow can cause loss of connectivity between satellite and receiver