Networking Ch. 1-4

Unicast address

Specifies a single node on a network

•Any of these server types can co-exist on the same machine (T/F)

T

Wall jacks (TIA/EIA standards)

T I A/E I A standard calls for each wall jack to contain at least one voice and one data outlet

ping (Packet Internet Groper)

Used to verify that T C P/I P is: •Installed •Bound to the N I C •Configured correctly •Communicating with the network

UDP

User Datagram Protocol. Used instead of TCP when guaranteed delivery of each packet is not necessary. UDP uses a best-effort delivery mechanism. •an unreliable, connectionless protocol:

•Port numbers are divided into three types:

Well-known ports - 0 to 1023 Registered ports - 1024 to 49151 Dynamic and private ports - 49152 to 65535

•To view a Window's workstation's A R P table, enter the command:

arp -a

•TLD servers hold information about

authoritative servers owned by various organizations

•Dynamic I P addresses are assigned _____

automatically assigned by a DHCP (Dynamic Host Configuration Protocol) server

VoIP gateway device

converts signals from a campus's analog phone equipment into IP data that can travel over the Internet, or which converts VoIP data from an internal IP network to travel over a phone company's analog telephone lines

INFO

unrestricted top-level domain

reversing an OS patch

use the patch's automatic uninstall utility

reverse a shared application upgrade

use the upgrade's automatic uninstall utility or maintain a complete copy of the previous installation of the application an reinstall over the upgrade

ORG

noncommercial organization

MAC (Media Access Control) address

•Hardware address of the source and destination NICs

•The route command allows you to view a host's routing table: (what command to use on Windows, Linux and Cisco IOS)

•On a Linux or UNIX system, use the command route •On a Windows-based system, use the command route print •On a Cisco I O S, use the command show ip route

Patch panel

•Panel of data receptors that can be mounted to a wall or a rack -Provides central termination point when many patch cables converge in a single location

alternative names for a MAC address

physical address, hardware address, or Data Link layer address

•Use ____ (command) to test for network connectivity

ping

what are network diagrams useful for

planning where to insert a new switch or determining how a particular router, gateway, or firewall interact

Connectivity devices

specialized devices that allow two or more networks or multiple parts of one network to connect and exchange data

Each OS (operating system) is configured to use one of two models to connect to network resources: ...

the peer-topeer model or the client-server model

Name resolution

the process of discovering the IP address of a host when you know the FQDN

•T C P uses a _____ to establish a connection

three-way handshake

Types of cables

•Patch cable—A relatively short length of cabling with connectors at both ends •Horizontal cabling—Connects workstations to the closest data room and to switches housed in the room •Backbone cabling—Consists of cables or wireless links that provide interconnection between the entrance facility and M D F and between M D F and I D Fs

What layer of OSI is the harware and harware protocols, ethernet and wifi

2. Data Link layer 1. Physical layer

Global unicast address prefix + first bits

2000::/3 + first 3 bits are always 001

•Class E begin with octets ____-____ and are used for _____________

240-254; research

Client

A computer making a request from another

-Fully qualified domain name (F Q D N)

A unique character-based name

DNS

Application layer client-server system of computers and databases

Router categories

Core routers, also called interior routers Edge routers, or border routers Exterior routers

Payload

Data that is passed between applications or utility programs and the OS

Session layer

Describes how data between applications is synched and recovered if messages don't arrive intact at the receiving application

link local unicast address prefix

FE80::/64

•Data rooms are often serviced by ____ that are separate from the rest of the building

H V A C systems

logical topology

Has to do with software, how access to the network is controlled, including how users and programs initially gain access to the network, and how specific resources, such as applications and databases, are shared on the network

•Domain names must be registered with an Internet naming authority that works on behalf of ____

ICANN

•IPv6 networks use a version of ICMP called ______

ICMPv6

what explains how to properly handle substances such as chemical solvents and how to dispose of them?

Material Safety Data Sheet (MSDS)

NET

Networks (such as an ISP)

Electrical and tool safety is generally regulated by

O S H A (Occupational Safety and Health Administration)

Multicast address

Packets are delivered to all nodes on a network

POP3

Post Office Protocol 3

Port Address Translation (P A T)

Process of assigning a TCP port number to each ongoing session between a local host and Internet host

continuity

(each cable segment transmits data reliably)

bend radius

(radius of the maximum arc into which you can loop a cable without impairing data transmission)

client-server network model

(which is sometimes called the client-server architecture or client-server topology), resources are managed by the NOS via a centralized directory database. The database can be managed by one or more servers, so long as they each have a similar NOS installed

antages of using peer-to-peer networks:

- They are simple to configure. For this reason, they may be used in environments in which time or technical expertise is scarce. • - They are often less expensive to set up and maintain than other types of networks. A network operating system, such as Windows Server 2016, is much more expensive than a desktop operating system, such as Windows 10 Professional.

P2P (peer-to-peer) network model

- the operating system of each computer on the network is responsible for controlling access to its resources without centralized control (no computer has more authority than another). - The computers, called nodes or hosts on the network, form a logical group of computers and users that share resources - Each computer on a P2P network controls its own administration, resources, and security.

changes to existing software - Patch

-A correction, improvement, or enhancement

•S L A (service-level agreement) + example

-A legally binding contract or part of a contract that defines the aspects of a service provided to a customer -Example: The service provided by an I S P

changes to existing software - Upgrade

-A major change to a software package that enhances the functionality and features of the software

changes to existing software - Rollback

-Also called backleveling or downgrading -Process of reverting to a previous version after attempting to patch or upgrade it

•When a computer is struggling to establish a network connection (action to take)

-Check its T C P/I P configuration settings

•If you are getting D H C P errors or if multiple clients are having trouble connecting to the network (actions)

-Check the settings on your D H C P server -Make sure the D H C P scope is large enough to account for the number of clients the network must support •Consider implementing a shorter lease time on larger networks

•S O W (statement of work)

-Documents in detail the work that must be completed for a particular project

•M O U (memorandum of understanding)

-Documents the intentions of two or more parties to enter into a binding agreement, or contract

•M L A (master license agreement)

-Grants a license from a creator, developer, or producer to a third party for the purposes of marketing or sublicensing, or distributing the product to consumers

I P v 4 addresses

-I P v 4 addresses have 32 bits and are written as four decimal numbers called octets •Each of the four octets can be any number from 0 to 255

Common network configuration errors:

-Incorrect netmask -Incorrect gateway -Duplicate IP address

(cable management) Documentation

-Keep your cable plant documentation accessible -Label every data jack or port, patch panel, and connector -Use color-coded cables for different purposes Update your documentation as you make changes to the network

changes to existing software - Installation

-New software to be installed on relevant devices and incorporated with network resources

•R F P (request for proposal)

-Request to vendors to submit a proposal for a product or service your company wants to purchase

•If the computer is not obtaining an I P address and related information from a D H C P server (action to take)

-Static settings might be using the wrong information -Try switching to D H C P

•Three transmission sent before data transmission: (TCP)

-Step 1—Request for a connection (S Y N) -Step 2—Response to the request (S Y N/A C K) -Step 3—Connection established (A C K)

O S P F (Open Shortest Path First) Characteristics

-Supports large networks—Imposes no hop limits (unlike R I P) -Uses a more complex algorithm for determining best paths -Shared data—Maintains a database of other routers' links -Low overhead, fast convergence—Demands more memory and C P U power for calculations, but keeps network bandwidth to a minimum and provides a very fast convergence time -Stability—Uses algorithms that prevent routing loops Multi-vendor routers—Supported by all modern routers

•tracert or traceroute (why might a trace test stop?)

-The device the trace is attempting to reach is down -It's too busy to process lower-priority messages such as U D P or I C M P -It does not accept the U D P or I C M P transmissions being sent because a firewall blocks these types of messages

•Information that can be obtained from the netstat command includes:

-The port on which a T C P/I P service is running -Which network connections are currently established for a client -How many messages have been handled by a network interface since it was activated -How many data errors have occurred on a particular network interface

•When terminating twisted-pair cabling, don't leave more than ____ of exposed cable before a termination

1 inch

•Class D begin with octets ____-____ and are used for _____________

224-239; multicasting

•A R P is a Layer _____ protocol that uses ____ in Layer ____

2; IP; 3

What layer of OSI is IP, ICMP, and ARP

3. Network Layer

What layer of osi is TCP or UDP

4. Transport layer

•Data portion of an Ethernet frame may contain from __to __bytes

46 to 1500 bytes

What layer of OSI is the TCP Suite and protocols HTTP, HTTPS, SMTP, TRPS

6. Presentation layer and 5. Session layer

What layer of OSI is the world wide web, email, FTP

7. Application Layer

Data Link layer MAC address

A MAC address is embedded on every NIC on the globe and is assumed to be unique to that NIC. A MAC address is 48 bits, written as six hex numbers separated by colons, as in 00:60:8C:00:54:99. Nodes on a LAN find each other using their MAC addresses also called physical address

Windows domain

A logical group of computers that a Windows Server can control

A method used by I P v 6 to transport I P v 6 packets through or over an I P v 4 network

A method used by I P v 6 to transport I P v 6 packets through or over an I P v 4 network

Tunneling

A method used by I P v 6 to transport I P v 6 packets through or over an I P v 4 network

•Administrative distance (A D)

A number indicating the protocol's reliability

•Transport layer port numbers

A port is a number used by the Transport layer to find an application. It identifies one application among several that might be running on a host. For example, a web server application is usually configured to listen for incoming requests at port 80

OSI (Open Systems Interconnection) reference model

A seven-layer model developed to categorize the layers of communication

•On I P v 4 networks, neighbor discovery is managed by ___ with help from ___

ARP; ICMP

A user can sign on to the network from any computer on the network and gain access to the resources that A D allows. What is this managed by?

Active Directory Domain Services (AD DS)

•Routers rate the reliability and priority of a routing protocol's data based on these criteria:

Administrative distance (A D) Convergence time Overhead

•I S-I S (Intermediate System to Intermediate System) + characteristics

An I G P and link-state routing protocol •Uses a best-path algorithm similar to O S P F •Is designed for use on core routers only (unlike O S P F) •Not handcuffed to I P v 4 (like O S P F) so it's easy to adapt to I P v 6 •Service providers generally prefer I S-I S because it's more scalable than O S P F

•Network layer I P address

An IP address is assigned to nearly every interface, which is a network connection made by a node on a network. An IP address can be used to find any computer in the world if the IP address is public on the Internet. Applications such as browsers can store and retrieve IP addresses. But for routing purposes, an IP address is used only at the Network layer

•E I G R P (Enhanced Interior Gateway Routing Protocol) + characteristics

An advanced distance-vector protocol that combines some of the features of a link-state protocol •Often referred to as a hybrid protocol •Fast convergence time and low network overhead •Easier to configure and less C P U-intensive than O S P F •Supports multiple protocols and limits unnecessary network traffic between routers Originally proprietary to Cisco routers

A remote application

An application that is installed and executed on a server, and is presented to a user working at a client computer.

____ don't share their resources directly with each other; instead, access is controlled by _______

Clients; entries in the centralized domain database

Edge routers, or border routers

Connect an autonomous system with an outside network

Socket + example

Consists of host's I P address and the port number of an application running on the host •Colon separates the two values •Example—10.43.3.87:23

Demarc (demarcation point)—

Device that marks where a telecommunications service provider's network ends and the organization's network begins

Gateway

Device that nodes use for access to the outside world

Core routers, also called interior routers

Direct data between networks within the same autonomous system (A S)

•netstat

Displays T C P/I P statistics and details about T C P/I P components/connections on a host

Rack diagram

Drawing that show devices stacked in a rack system

Link-state routing protocols

Enables routers to communicate beyond neighboring routers in order to independently map the network and determine the best path

Work area

Encompasses workstations, printers, and other network devices

Port numbers

Ensure data is transmitted to the correct process among multiple processes running on the computer

Unique local unicast address prefix

FC00::/7 OR FD00::/8

multicast address prefix

FF00::/8

Network diagrams (3 things)

Graphical representations of a network's devices and connections •May show physical layout, logical topology, I P address reserves, names of major network devices, and types of transmission media •provide broad snapshots of a network's physical or logical topology

CNAME (Canonical Name) record

Holds alternative names for a host

T X T (Text) record

Holds any type of free-form text

AA A A (Address) record

Holds the name-to-address mapping, the I P address is an I P v 6 type I P address

Racks

Holds various network equipment

___ on IPV6 networks performs the functions of ICMP and ARP on IPv4 networks

ICMPv6

•Ethernet ____ (gen???) is the current standard. What does it do?

II •Adds both a header and a trailer to the payload •Creates a frame around the payload

____ adds its own Network layer header to the segment or datagram

IP

The principal protocol used by the Network layer is ____

IP (Internet Protocol)

•Routing tables contain _____ and ______ that identify a network that a host or another router belongs to

IP addresses; network masks

what does IP rely on to find the best route for a packet? explain and examples

IP relies on several supporting protocols to find the best route for a packet when traversing several networks on its way to its destination. These supporting protocols include ICMP (Internet Control Message Protocol) and ARP (Address Resolution Protocol). You'll learn more about these protocols later

Explain autoconfiguration IpV6

IP v 6 addressing is designed so that a computer can autoconfigure its own link local IP address Step 1—The computer creates its I P v 6 address •Uses F E 8 0::/64 as the first 64 bits (called prefix) •Last 64 bits can be generated in two ways: -Randomly generated -Generated from the network adapter's MAC address •Step 2—The computer checks to make sure its I P address is unique on the network •Step 3—The computer asks if a router on the network can provide configuration information (message is called a R S or router solicitation) •If a router responds with D H C P information, the computer uses whatever information this might be (called a R A or router advertisement) -Such as the I P addresses of D N S server or the network prefix •Process is called prefix discovery -The computer uses the prefix to generate its own link local or global I P v 6 address by appending its interface I D to the prefix

IMAP4

Internet Message Access Protocol v4

top-level domain

Last part of the FQDN -> Domains (including .net, .org, .com, .mil. and the set .xx country codes) at the end of a domain name are the highest level of the domain name hierarchy.

Protocols

Methods and rules for communication between networked devices

physical topology

Mostly refers to a network's hardware and how computers, other devices, and cables fit together to form the physical network

The peer-to-peer model can be achieved using any assortment of desktop, mobile, or tablet operating systems, but the client-server model requires one or more _______

NOSes (network operating systems), which control access to the entire network

Session Layer Most tasks are performed by the ___ when an application makes an ___ call to the ___

OS; API; OS

Four types of changes to existing software

Patch Upgrade Rollback Installation

reverse an OS upgrade

Prior to the upgrade, make a complete backup of the system; to roll back, restore the entire system from the backup; uninstall an operating system upgrade only as a last resort

Encapsulation

Process of adding a header to the data inherited from the layer above

System life cycle (SLC)

Process of designing, implementing, and maintaining an entire network

Address translation

Process where a gateway device substitutes the private I P addresses with its own public address •When these computers need access to other networks or Internet

Routing metrics

Properties of a route used by routers to determine the best path to a destination

I C M P (Internet Control Message Protocol)

Protocol used by the echo request/reply to carry error messages and information about the network

decapsulation

Removing a header or trailer from a lower OSI layer.

Network layer

Responsible for moving messages from one node to another until they reach the destination host

Presentation layer + example

Responsible for reformatting, compressing, and/or encrypting data in a way that the receiving application can read Example •An email message can be encrypted at the Presentation layer by the email client or by the O S

Transport layer

Responsible for transporting Application layer payloads from one application to another

•Two variations of N A T to be aware of:

S N A T (Static (or Source) Network Address Translation) D N A T (Dynamic Network Address Translation)

_____is used to send email to a recipient's email server, and _____or _____ is used by the client to receive email

SMTP; POP3; IMAP4

DNS server

Server responsible for tracking computer names and their IP addresses

SMTP

Simple Mail Transfer Protocol

Physical layer

Simplest layer and is responsible for sending bits via a wired or wireless transmission

A (Address) record

Stores the name-to-address mapping for a host

•The ___, ___, and ____ layers are intertwined

The Application, Presentation, and Session layers

•Overhead

The burden placed on the underlying network to support the protocol

AD (Active Directory)

The centralized directory database that contains user account information and security for the entire group of computers

S N A T (Static (or Source) Network Address Translation)

The gateway assigns the same public IP address to a host each time it makes a request to access the Internet

D N A T (Dynamic Network Address Translation)

The gateway has a pool of public address that it is free to assign to a local host when it makes a request to access the Internet

Inventory management + benefits

The monitoring and maintaining of all assets that make up a network: •Simplifies maintaining and upgrading a network •Provides network administrators with information about the costs and benefits of certain types of hardware or software

BIND (Berkeley Internet Name Domain)

The most popular DNS server software. BIND is free, open source software that runs on Linux, UNIX, and Windows platforms.

Network mapping

The process of discovering and identifying the devices on a network:

Network services

The resources a network makes available to its users •Includes applications and the data provided by these applications

What makes U D P more efficient than T C P

UDP provides no error checking, sequencing, or flow control (so while it's not as reliable/secure it doesn't spend time on that and therefore is more efficient)

Types of I P v 6 addresses

Unicast address Multicast address Anycast address see ch3 slide 18

IGP (interior gateway protocols)

Used by core routers and edge routers within autonomous systems and are often grouped according to the algorithms they use to calculate best paths:

EGP (exterior gateway protocols)

Used by edge routers and exterior routers to distribute data outside of autonomous systems •The only E G P currently in use is B G P

Routing protocols

Used by routers to communicate with each other to determine the best path

P T R (Pointer) record

Used for reverse lookups

Subnet mask

Used to indicate what portion of an I P address is the network portion (network ID) and what part is the host portion (host ID)

•The Transport layer header addresses the receiving application by a number called ____

a port number

Ethernet

a system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems. •Most important Data Link layer standard •Capable of running on a variety of network media •Offers excellent throughput at a reasonable cost •Most popular network technology used on modern LANs

VoIP telephone equipment

also known as IP telephony, is the use of any network (either public or private) to carry voice signals using TCP/IP protocols

A hub

an inefficient and outdated networking device that has been replaced by switches. A hub accepted signals from a transmitting node and repeated those signals to all other connected nodes in a broadcast fashion. On Ethernet networks, hubs once served as the central connection point for a star topology.

Link (sometimes called local link)

any LAN bounded by routers

server

any computer or program that provides a service, such as data or other resources, to other devices

•I P v 6 devices use Neighbor Discovery Protocol (N D P) to ________

automatically detect neighboring devices and automatically adjust when neighboring nodes fail or are removed

•Do not exceed the cable's prescribed _____

bend radius

•A R P relies on _______

broadcasting

COM

commercial

Wiring schematic

graphical representation of a network's wired infrastructure •In detailed form, it shows every wire necessary to interconnect network devices

•TCP/IP protocols add a ____ to data inherited from the layer above it

header

•A topology that combines topologies is known as a _________

hybrid topology

•D N S name servers are organized in what way?

in a hierarchical structure •At the root level, 13 clusters of root server hold information used to locate top-level domain (T L D) servers

Where are the protocols of layer 1 and 2 programmed?

into firmware of a computer's N I C and other hardware

IP address

is an address assigned to each node on a network, which the Network layer uses to uniquely identify them on the network.

Application programming interface (A P I) call

is the method an application uses when it makes a request of the O S

A router

joins two or more networks and passes packets from one network to another

•In addition to protecting against ESD ...

lways shut down and unplug a computer before working inside it

•Static I P addresses are assigned ______

manually by the network administrator

•I P operates at the ______layer of the O S I model: (what actions does it perform?)

network layer; •Specifies where data should be delivered •Identifies the data's source and destination I P addresses

•Reverse D N S lookup—To find the host name of a device whose I P address you know (how do you do this?)

nslookup 69.23.208.74

Controlling how users and programs get access to resources on a network is a function of the ________ used on the network

operating system

•Each organization that provides host services is responsible for ________

providing and maintaining its own D N S authoritative servers for public access

Rack height is measured in _____ with the industry standard being ___tall—about _ feet. Half-racks are usually ___ - ___ tall.

rack units (RU or U); 42U; 6 feet; 18U-22U

ARPA

reverse lookup domain (special internet function)

•T I A/E I A's joint 568 Commercial Building Wiring Standard: •Also known as ______

structured cabling

Authoritative server

the authority on computer names and their IP addresses for computers in their domains

what does the T I A/E I A's joint 568 Commercial Building Wiring Standard describe? where is it applied? where is it best?

the best way to install networking media to maximize performance and minimize upkeep •Apply no matter what type of media, transmission technology, or networking speeds are involved •Based on hierarchical design and assumes a network is based on the star topology

(In TCP) After the three initial messages, _______

the payload or data is sent

reverse a client software upgrade

use the upgrade's automatic uninstall utility, or reinstall the previous version of the client on top of the upgrade

the NOS is responsible for:

• Managing data and other resources for a number of clients • Ensuring that only authorized users access the network • Controlling which types of files a user can open and read • Restricting when and from where users can access the network • Dictating which rules computers will use to communicate • In some situations, supplying applications and data files to clients

disadvantages of using traditional peer-to-peer networks:

• They are not scalable, which means, as a peer-to-peer network grows larger, adding or changing significant elements of the network may be difficult. • They are not necessarily secure, meaning that in simple installations, data and other resources shared by network users can be easily discovered and used by unauthorized people. • They are not practical for connecting more than a few computers because it's too time consuming to manage the resources on the network. For example, suppose you want to set up a file server.

Client-server network advantages relative to peer-to-peer networks

• User accounts and passwords to the network are assigned in one place. • Access to multiple shared resources (such as data files or printers) can be centrally granted to a single user or groups of users. • Problems on the network can be monitored, diagnosed, and often fixed from one location. • Client-server networks are also more scalable than peer-to-peer networks. In other words, it's easier to add computers and other devices to a client-server network.

Several types of records, called resource records are kept in a D N S database

•A (Address) record •A A A A (Address) record •C NAME (Canonical Name) record •P T R (Pointer) record •N S (Name Server) record •M X (Mail Exchanger) record •S R V (Service) record TXT (Text) record

Pathping

•A Windows utility that combines elements of both ping and tracert to provide deeper information about network issues along a route •Sends multiple pings to each hope along a route, then compiles information into a single report

A backbone

•A central conduit that connects the segments (pieces) of a network •Might use higher transmission speeds and different cabling than network cables connected to computers

In client-server applications

•A client computer requests data or a service from a second computer, called the server

Routing table

•A database that maintains information about where hosts are located and the most efficient way to reach them •Routers rely on them to identify which router is the next hop to reach a particular destination host

Router

•A device that manages traffic between two or more networks •Can help find the best path for traffic to get from one network to another

tcpdump

•A free, command-line packet sniffer that runs on Linux and other Unix O Ss •Captures traffic that crosses a computer's network interface •Output can be saved to a file that you can filter or play back •You must either use the sudo command or log in as root to access tcpdump

Discovering neighbor devices

•A process used by routers to learn about all of the devices on their networks:

Network Address Translation (N A T)

•A technique designed to conserve public I P addresses needed by a network

Star topology

•All devices connect to one central device (usually a switch)

nslookup (name space lookup)

•Allows you to query the D N S database from any computer on a network: •To find the host name of a device by specifying its I P address, or vice versa •Useful for verifying a host is configured correctly or for troubleshooting D N S resolution problems

O S P F (Open Shortest Path First)

•An I G P and a link-state protocol used on interior or border routers •Introduced as an improvement to R I P

D M Z or demilitarized zone

•Area between two firewalls

Dynamic routing

•Automatically calculates the best path between two networks and maintains this information in a routing table •Router can detect problems with failed or congested routes and reroute messages through a different path

dig (domain information groper)

•Available on Linux and macO S •Provides more detailed information than nslookup and uses more reliable sources of information to output its results

Microsoft D N S Server

•Built-in D N S service in the Windows Server O S

•I C M P announces transmission failures to the sender but ____

•But does not correct errors it detects

•Ways the resolution process can get more complex:

•Caching server typically is not the same machine as the authoritative server -Caching server exists only to resolve names for its own local clients •Name servers within a company might not have access to root servers •A T L D name server might be aware of an intermediate name server rather than the authoritative name server

Layer 3 switch

•Capable of interpreting Layer 3 data and works much like a router: •Usually faster and less expensive •Primary difference is the way the hardware is built

Layer 4 switch

•Capable of interpreting Layer 4 data: •Also known as content or application switches •Enables switch to perform advanced filtering, keep statistics, and provide security functions Typically used as part of a network's backbone

Static electricity can cause two types of damage

•Catastrophic failure—destroyed beyond use •Upset failure—shorten the life of a component

M D F (main distribution frame/facility)

•Centralized point of interconnection for an organization's LAN or WAN (also called M C or main cross connect)

•Incorrect time (what to do)

•Check a domain computer's time source from a Command Prompt window by entering w32tm /query /source

IPv4 classes (+ types)

•Class A, Class B, Class C, Class D, and Class E Public classes: A, B, C are available for use on the internet

•Protecting against static electricity:

•Computer components are grounded inside a computer case

Routers can do the following:

•Connect dissimilar networks (LANs and WANs) •Interpret Layer 3 and often Layer 4 addressing •Determine the best path for data to follow from point A to point B •Reroute traffic if the path of first choice is down but another path is available

•Three characteristics of T C P:

•Connection-oriented—T C P ensures that a connection or session is established by using a three-step process called a three-way handshake •Sequencing and checksums—T C P sends a character string called a checksum that is checked by the destination host along with a sequence number for each segment •Flow control—Gauges rate of transmission based on how quickly recipient can accept data

Four addressing methods

•Data Link layer MAC address •Network layer I P address •Transport layer port numbers •Application layer F Q D Ns, computer names, and host names

Lifting heavy objects—Follow these guidelines

•Decide which side of object to face so load is most balanced •Stand close to the object with your feet apart •Keep your back straight, bend knees and grip load •Lift with your legs, arms, and shoulders (not your back or stomach) •Keep the load close to your body and avoid twisting your body while you're holding it •To put the object down, keep your back as straight as possible and lower object by bending your knees

Application layer

•Describes the interface between two applications, on separate computers

•An A R P table can contain two types of entries:

•Dynamic—Created when a client makes an A R P request that could not be satisfied by data already in the A R P table Static—Those someone entered manually using the ARP utility (arp command)

where can a MAC address be found?

•Embedded on every network adapter and are considered short-range addresses that can only find nodes on the local network

Fire Suppression Systems

•Emergency alert system •Portable fire extinguishers •Emergency power-off switch •Suppression agent

Data room

•Enclosed space that hold network equipment (also called data closet, data center, equipment room, or telecommunications room)

Exceptions to Ethernet frame size limitations

•Ethernet frames on a V LAN can have an extra 4-byte field between the Source address field and the Type field •Some special-purpose networks use a proprietary version of Ethernet that allows for a jumbo frame

Routers may perform any of the following optional functions:

•Filter broadcast transmissions •Prevent certain types of traffic from getting to a network •Support simultaneous local and remote connectivity •Provide high network fault tolerance through redundant components such as power supplies •Monitor network traffic and report statistics Diagnose internal or other connectivity problems and trigger alarms

•Traditional MAC addresses contain two parts:

•First 24 bits are known as the O U I (Organizationally Unique Identifier) or manufacturer-I D -Assigned by the I E E E •Last 24 bits make up the extension identifier or device I D -Manufacturers assign each N I C a unique device I D

Routing metrics list

•Hop count •Theoretical bandwidth and actual throughput •Delay, or latency, on a potential path •Load, or the traffic or processing burden •M T U (maximum transmission unit) or the largest I P packet size in bytes allowable without fragmentation •Routing cost, or a value assigned to a particular route •Reliability of a potential path Topology of a network

nslookup modes

•Interactive—To test multiple D N S servers at one time •Noninteractive—Test a single D N S server

(DMS Server Software) For a more secure network (things to do)

•Internal and external DNS queries should be handled by different DNS servers •Can use a firewall to filter or block traffic between networks

TCP IP layers and their functions

•Layers 7, 6, and 5—Data and instructions, known as payload, are generated by applications running on source host •Layer 4—A Transport layer protocol, usually T C P or U D P, adds a header to the payload •Includes a port number to identify the receiving app •Layer 3—Network layer adds it own header and becomes a packet •Layer 2—Packet is passed to Data Link layer on N I C, which encapsulates data with its own header and trailer, creating a frame •Layer 1—Physical layer on the N I C receives the frame and places the transmission on the network

•Essential documentation:

•Logical and physical connections on a network •Inventory management •I P address utilization •Vendors •Internal operating procedures •Policies •Standards

•Having up-to-date and detailed documentation of your network is essential for the following reasons:

•Makes communication with coworkers more efficient •Speeds up troubleshooting efforts •Puts information at your fingertips when facing similar problems in the future

•I P is an unreliable, connectionless protocol means what?

•Means that I P does not guarantee delivery of data and no session is established before data is transmitted •I P depends on T C P to ensure messages are put back together in the right order and to ensure each message reaches the correct application on the receiving host

Servers that have a N O S installed require:

•More memory, processing, and storage capacity

Static routing + example

•Network administrators configures a routing table to direct messages along specific paths •Example—A static route between a small business and its ISP

fragmentation

•Network layer protocol will divide large packets into smaller packets •Process called fragmentation

Network mappings tools

•Nmap—One of the most popular tools used for network mapping •Zenmap—N map's G U I option

OSI Layers in order

•Physical, Data Link, Network, Transport, Session, Presentation, Application

Four common types of D N S servers

•Primary D N S server—The authoritative name server for the organization -Holds the authoritative DNS database for the organization's zones •Secondary D N S server—Backup authoritative name server for the organization •Caching D N S server—Accesses the public D N S data and caches the D N S information it collects •Forwarding D N S server—Receives queries from local clients but doesn't work to resolve the queries

The same change management principles apply to any type of change:

•Process all changes through the proper channels •Minimize negative impacts on business procedures •Plan thoroughly to maximize the changes of a successful change on the first attempt •Document each change throughout the process

Protocol header

•Protocols add their own control information in an area at the beginning of the payload (called a header)

Application layer protocols are used by programs that fall into two categories

•Provide services to a user, such as a browser and Web server •Utility programs that provide services to the system, such as S N M P that monitor and gather information about network traffic

I D F (intermediate distribution frame)—

•Provides an intermediate connection between the M D F and end-user equipment on each floor and in each building

•Common software and hardware changes for managing change and maintaining a network efficiency and availiability

•Range from installing patches to replacing network backbone

Switch

•Receives incoming data from one of its ports and redirects it to another port or multiple ports •Will send the data to its intended destination

•Two types of D N S requests:

•Recursive—A query that demands a resolution or the answer "It can't be found" •Iterative—A query where the local server issues queries to other servers -Other servers only provide information if they have it Do not demand a resolution

Exterior routers

•Refers to any router outside the organization's A S -Direct data between autonomous systems

S L C includes

•Removal and disposal of outdated assets •Addition of compatible, updated devices

•Managing change while maintaining network's efficiency and availability: + what is required for enterprise work?

•Requires good planning •Network users need to know when to expect certain network resources to be unavailable •You may also need to know the change management documentation that might be required for an enterprise-scale network

Difference between router and switch:

•Router is like a gateway between networks and belongs to two or more local networks •Switch belongs only to its local network

ipconfig

•Shows current T C P/I P addressing and domain name information on a Windows computer •Use ipconfig/all to see a more complete summary of T C P/I P addressing information

A U D P header contains only four fields

•Source port, Destination port, Length, and Checksum •Note: Use of Checksum field in U D P is optional in I P v 4, but required in I P v 6

Two main Transport layer protocols are

•T C P (Transmission Control Protocol)—Makes a connection with the end host, checks whether data was received; called a connection-oriented protocol •U D P (User Datagram Protocol)—Does not guarantee delivery by first connecting and checking whether data is received; called a connectionless protocol

Two primary protocols

•TCP (Transmission Control Protocol) •IP (Internet Protocol)

•TCP/IP—A suite of protocols including:

•TCP, IP, UDP, ARP, and many others

•M T U (maximum transmission unit)

•The largest size that routers in a message's path will allow at the Network Layer

Protocol data unit (PDU) + alternative names

•The technical name for a group of bits as it moves from one layer to the next and from one LAN to the next •Technicians loosely call this group of bits a message or a transmission

Convergence time

•Time it takes to recognize a best path in the event of a change or network outage

Duplicate MAC Addresses

•Two devices on the same network with the same MAC address is a problem •MAC addresses can be impersonated -A security risk called SPOOFING •Happens most often when managing multiple virtual devices on a large network •Most switches will detect the problem and produce helpful error messages

•Specialized products can monitor the critical factors of a data closet's environment:

•Unacceptable temperature •Humidity •Airflow conditions

Tips for labeling and naming conventions

•Use names that are as descriptive as possible •Only include fields that are essential in identifying the device •Don't overcomplicate the name with useless or redundant information •Use established naming conventions •Think big-picture-down-to-details •Consider any security risks from details included in your naming convention •Use color-coded cables for different purposes and use cable tags to identify each cable's purpose •Label the ports and jacks that cables connect to •Where labels won't fit on the device, draw a simple diagram of each device that indicates how each port is used •Use a portable label maker and use labels that are durable and are designed to stick to plastic and metal

What is UDP useful for

•Useful for live audio or video transmissions over the Internet •Also more efficient for carrying messages that fit within one data packet

ifconfig

•Utility to view and manage T C P/I P settings •If your Linux or UNIX system provides a G U I •Open a shell prompt, then type ifconfig

physical layer - can be transmitted as

•Wavelengths in the air •Voltage on a copper wire •Light (via fiber-optic cabling)

OSHA guidelines when using power tools:

•Wear personal protective equipment (P P E) •Keep all tools in good condition and properly store tools not in use •Use the right tool for the job and operate the tool according to the manufacturer's instructions Watch out for trip hazards, so you and others don't stumble on a tool or cord

Before touching a component, ground yourself by

•Wearing an E S D strap around your wrist that clips onto the chassis or computer case •Touching the case before touching any component inside the case •Storing a component inside an antistatic bag

List of several popular client-server applications

•Web service •Email services •F T P service •Telnet service •Remote applications •Remote Desktop

Dual stacked

•When a network is configured to use both I P v 4 and I P v 6

•I C M P can indicate:

•When part of a network is congested •When data fails to reach its destination •When data has been discarded because the allotted T T L has expired

tracert and traceroute

•Windows tracert utility uses I C M P echo requests to trace the path from one networked node to another, identifying all intermediate hops between the nodes •Linux, UNIX, and O S X systems use the traceroute utility to send U D P messages to a random port on the destination node (concept is the same as tracert) •Both utilities employ a trial-and-error approach to discover the nodes at each hop from source to destination

Use a cable tester to verify ____

•continuity

Sensitive electronic components can be damaged by

•electrostatic discharge (E S D)

where does the link layer put control information?

•in a Link layer header and at the end of the packet in a trailer

What is DNS made up of

•namespace—The entire collection of computer names and their associated IP addresses stored in databases on D N S name servers around the globe •name servers—Hold databases, which are organized in a hierarchical structure •resolvers—A D N S client that requests information from D N S name servers

What info does the Material Safety Data Sheet include?

•physical data, toxicity, health effects, first aid, storage, shipping, disposal, and spill procedures

•Command-link tools are a great resource to troubleshoot network problems

•ping •ipconfig (Windows only) •ifconfig (Linux only) •nslookup dig (Linux only)

•M S A (master service agreement) + example

-A contract that defines the terms of future contracts between parties -Such as payment terms or arbitration arrangements

Troubleshooting steps used by most expert networking troubleshooters

1. Identify problem (Gather information, Identify symptoms, Question users, Determine if anything has changed) 2. Establish theory of probable cause (Question the obvious) 3. Test theory to determine cause (If theory confirmed, determine next steps, If theory not confirmed, establish new theory or escalate) 4. Establish action plan 5. Implement solution or escalate the problem 6. Verify full functionality (Implement preventative measures if applicable) 7.Document findings, actions, outcomes

•The header and FCS make up the ____ (how many bytes) "frame" around the data

18-byte

Distance-vector routing protocols

Calculate path on the basis of the distance to that destination

Global unicast address vs Link local unicast address

Can be routed on the Internet (global) vs Can be used for communicating with nodes in the same link

Anycast address

Can identify multiple destinations, with packets delivered to the closest destination

who sets the standard for diagram symbols used to represent network devices?

Cisco Systems

IPv6 addresses

IPv6 addresses have 128 bits and are written as eight blocks of hexadecimal •Each block is 16 bits •Leading zeros in a four-character hex block can be eliminated •If blocks contain all zeroes, they can be written as double colons (::), only one set of double colons is used in an I P address

M X (Mail Exchanger) record

Identifies a mail server and is used for email traffic

S R V (Service) record

Identifies the hostname and port of a computer that hosts a specific network services besides email

Entrance facility

Incoming network (such as Internet) connects with the school or corporate network

N S (Name Server) record

Indicates the authoritative name server for a domain

•B G P (Border Gateway Protocol) + characteristcs

The only current E G P and is known as the "protocol of the Internet" •Can span multiple autonomous systems •A path-vector routing protocol that communicates via B G P-specific messages that travel between routers •Determines the best paths based on many different factors •Can be configured to follow policies that might avoid a certain router or instruct a group of routers to prefer a particular route The most complex of the routing protocols

•T C P operates in the _________ of O S I model

Transport layer

Neighbors (ipv6)

Two or more nodes on the same link

what determines the link layer protocol that is used? + examples

Type of networking hardware or technology used on a network •Ethernet and Wi-Fi are examples

NOS examples

Windows Server 2016, Ubuntu Server, and Red Hat Enterprise Linux (Ubuntu and Red Hat are versions of Linux)

I C M P

a Network layer, core protocol that reports on the success or failure of data delivery •Provides critical information for troubleshooting network problems

•Three switches daisy-chained together in a single line is said to use_______________

a bus topology

•In U D P, the message is called ____

a datagram

Grounding

a device is connected directly to the earth

what is the entire link layer called

a frame

network

a group of computers and other devices (such as printers) that are connected by some type of transmission media

An interface

a node's attachment to a link

•The entire Network layer message is called ____

a packet

A network begins at the ____and ends at a ___

demarc; workstation

A topology

describes how the parts of a whole work together. When studying networking, you need to understand both the physical topology and the logical topology of a network

•A R P works in conjunction with I P v 4 to _______

discover the MAC address of a host or node on the local network •And to maintain a database that maps IP addresses to MAC addresses on the local network

What does TCP do if message is too large

divides it into smaller messages called segments

•The ping utility sends out a signal called an _____request to another device (request for a response) •Other computer responds in the form of _____

echo; an echo reply

•Required process will vary but expect the following regarding documentation (when wanting to change something in an organization):

•Submit a change request document •Understand and follow the approval process •The change is project managed (change coordinator is usually assigned) •Provide additional documentation that could include: -Network configuration -IP address utilization -Additions to the network -Physical location changes Close the change