Networking

The individuals most responsible for installing rogue access points are typically not hackers, but rather . . .

. . . they are employees not realizing the consequences of their actions

What three new security features did TKIP and WPA implement in order to address security problems encountered in WEP protected networks?

1. a key mixing function that combines the secret root key with the initialization vector before passing it to the RC4 cipher initialization 2. Second, WPA implements a sequence counter to protect against replay attacks. Packets received out of order will be rejected by the access point. Finally, TKIP implements a 64-bit Message Integrity Check (MIC).

TKIP's enhancements

1. required key length is increased from 64 bits to 128 bits 2. IV is increased from 24 bits to 48 bits (effectively eliminating collisions). 3. unique "base key" is created for each wireless device using a master key derived in the authentication process along with the sender's

Distributed Denial of Service (DDoS) attack

11

IP-enabled technologies

11

access control or HVAC data

11

physical and logical security systems

11

IPv6 extended the 32-bit IP address space to ______ bits, allowing up to __________ addresses.

128, 2^128,

A switch is an example of a layer-________ device.

2

Each hexadecimal digit represents how many binary digits?

4

How many bits in a MAC address?

48 bits

The protocol data unit (PDU) encapsulation is completed in which order?

<<Data, segments, packets, frames, bits>>. The PDU encapsulation method defines how data is encoded as it goes through each layer

A(n) _________ server is used to control whether someone gets access to the network.

Authentication

What are some functionality built into PPP ?

Authentication, Compression, Error Detection

Why is a router considered a DTE ?

Because of its relationship to a CSU/DSU, i.e, it is passing data to the CSU/DSU, which will forward the data to the service provider

bluetooth

Bluetooth (BT) is a short-distance RF technology used in WPANs. Bluetooth uses FHSS and hops across the 2.4 GHz ISM band at 1,600 hops per second. Older Bluetooth devices were known to cause severe all-band interference. Newer Bluetooth devices utilize adaptive mechanisms to avoid interfering with 802.11 WLANs

BOOTP

Boot Protocol/Bootstrap Protocol: computer networking protocol used in Internet Protocol networks to automatically assign an IP address to network devices from a configuration server. BOOTP was originally defined in RFC 951. DHCP is the successor to BOOTP

BGP

Border Gateway Protocol, standardized exterior gateway protocol designed to exchange routing & reachability info among autonomous systems (AS) on Internet. Classified as path vector protocol. Makes routing decisions based on paths, network policies, rule-sets configured by a network admin. Is involved in making core routing decisions

load balancing

Distributing a computing or networking workload across multiple systems to avoid congestion and slow performance

Explain steps of CSMA/CD

Each device senses whether the line is idle & available for use. If so, one device begins to transmit its first frame. If another device tries to send at same time, a collision occurs & the frames are discarded. Each device then waits a random amount of time & retries until successful in getting its transmission sent.

(True/False) IPv6 was enabled by default in Microsoft Windows XP SP2

False, it had to be explicitly installed and enabled. Proper IPv6 support was added with the Advanced Networking Pack and updated in the Service Pack 2.

(True/False) ARP can be routed across internetworking nodes

False. It is only communicated within the boundaries of a single network

redundancy

Fault tolerant networks depend on multiple paths between the source and destination of a message. If one path fails, the messages can be instantly sent over a different link. Having multiple paths to a destination is known as redundancy

most prominently known WAN protocols used in the latest Cisco exam objectives

Frame Relay, ISDN, HDLC, PPP, PPPoE, cable, DSL, MPLS, ATM, Cellular 3G/4G, VSAT, and Metro Ethernet

IEEE 802.3z

Gigabit Ethernet. 1000BASE-X Gbit/s Ethernet over Fiber-Optic at 1 Gbit/s (125 MB/s)

the only WAN protocols you'll usually find configured on a serial interface are:

HDLC, PPP, and Frame Relay

HDLC

High-Level Data-Link Control (HDLC) derived from Synchronous Data Link Control (SDLC), which was created by IBM as a Data Link connection protocol. HDLC works at the Data Link layer and creates very little overhead compared to Link Access Procedure, Balanced (LAPB).

what task group designed TKIP?

IEEE 802.11i

What is a *logical port* ?

Logical ports are used to connect an application that runs on the TCP/IP protocol. A port is a number between 1 and 65,536 & is a logical value assigned to specific applications or services. Many TCP segments come into any computer. The computer needs some way to determine which TCP segments go to which applications. A Web server, for example, sees a lot of traffic, but it "listens" or looks for TCP segments with the Destination port number 80, grabs those segments, and processes them.

PPP

Point-to-Point Protocol. Establishes direct connection between two nodes & can connect two routers directly w/out any host or other networking device in between. Can provide authentication, encryption & compression. Widely used by ISPs to enable dial up to Internet; also used by some ISPs for DSL and cable modem authentication, in the form of PPP over Ethernet. PPP is part of Layer 2 Tunneling Protocol, a core part of Microsoft's secure remote access solution for Windows 2000 and beyond.

Trivial File Transfer Protocol (TFTP)

TFTP is a simple protocol for transferring files, implemented on top of the UDP/IP protocols using well-known port number 69. TFTP was designed to be small and easy to implement, and therefore it lacks most of the advanced features offered by more robust file transfer protocols. TFTP only reads and writes files from or to a remote server. It cannot list, delete, or rename files or directories and it has no provisions for user authentication. Today TFTP is generally only used on local area networks (LAN). (port 69)

Network convergence

The efficient coexistence of telephone, video, and data communication within a single network, offering convenience and flexibility not possible with separate infrastructures

FF:FF:FF:FF:FF:FF

The ethernet broadcast frame which will be sent to all devices within the same broadcast domain

c-suite

The highest-level executives in senior management usually have titles beginning with "chief" forming what is often called the C-Suite.

advantage of UDP

The lack of retransmission delays makes it suitable for real-time applications such as Voice over IP, online games, and many protocols using Real Time Streaming Protocol

Circuit switching

big advantage is cost; most plain old telephone service (POTS) and ISDN dial-up connections are not flat rate, which is their advantage over dedicated--you pay only for what you use, only when call is established. No data can transfer before end-to-end connection is established; uses dial-up modems or ISDN and is used for lowbandwidth data transfers. Some people do still have ISDN; it's still viable and there are a few who still use a modem now and then. And circuit switching can be used in some of the newer WAN technologies as well

CSU/DSU

channel service unit/data service unit (CSU/DSU) is a device that is used to connect data terminal equipment (DTE) to a digital circuit, such as a T1/T3 line.

cio

chief information officer

computer network

collection of wired and wireless communication links through which computers and other hardware devices exchange data (or messages)

single point of failure

component or entity in a system which, if it no longer functions, would adversely affect the entire system

Central office (CO)

connects the customer's network to the provider's switching network. Make a mental note that a central office (CO) is sometimes also referred to as a point of presence (POP)

Local loop

connects the demarc to the closest switching office (central office)

primary goal of routing protocols

construction of routing tables

BGP

counts the number of traversed autonomous systems between the local router and the destination network and uses the autonomous system count to select the best path

network bridge

creates single aggregate network from multiple communication networks or network segments. Base technology for network switch.

Software defined networking

cuts the control plane of individual devices out of the picture and lets an all-knowing program called a network controller dictate how both physical and virtual network components move traffic through the network

DTE

data terminal equipment -- any device that stores or generates data; a source or destination for digital data, e.g., PCs, servers, routers

host

data-producing entity attached to a network, and it has been primarily a computer. Oftentimes, hosts are also called end devices, end systems, or end stations.

routing table

database which keeps track of paths

The reverse of encapsulation is called _______________ and is sometimes called ____________________.

de-multiplexing, de-encapsulation

circuit switching (Odom)

dedicated physical circuit path must exist between the sender and the receiver for the duration of the "call." Used heavily in the telephone company network.

history of UDP

designed by David P. Reed in 1980 and formally defined in RFC 768

The router inspects each packet's ______________ and then sends it out the correct port

destination IP address

DNS is about resolving what to what?

domain names to IP addresses

2 different types of ARP entries:

dynamic and static

Fully meshed topology

each routing node on the edge of a given packetswitching network has a direct path to every other node on the cloud, provides a high level of redundancy, but the costs are the highest

SLIP (Serial Line Internet Protocol)

encapsulation of Internet Protocol designed to work over serial ports/router connections. On PCs, largely replaced by PPP which has more features. On microcontrollers, SLIP is still the preferred way of encapsulating IP packets due to very small overhead.

Why is PPP considered superior to SLIP ?

error detection & data compression features, which SLIP lacks & the capability to use dynamic IP addresses

RFC 1918

facilitates expansion of usable no. of IP addresses w/in IPV4; stopgap solution to prevent exhaustion of public IPs before adoption of IPV6; creates standards by which networking equipment assigns IP addresses in private network; private network can use single public IP address; reserves following ranges of IP addresses that canNOT be routed on the Internet: 10.0.0.0 - 10.255.255.255 (10/8 prefix), 172.16.0.0 - 172.31.255.255 (172.16/12 prefix), 192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

primary function of a router

forward a packet toward its destination network, which is the destination IP address of the packet.

Further describe the setup of a *demarcation point*

generally a device in a telecommunications closet owned and installed by the telecommunications company (telco). It's your responsibility to cable (extended demarc) from this box to the CPE, which is usually a connection to a CSU/DSU, although more recently we see the provider giving us an Ethernet connection

host (2)

generally a source or a destination of data in transit, and it has been predominantly a general purpose or high-performance computer

switches/bridges work at the Data Link layer and filter the network using what?

hardware (MAC) addresses

router

hardware or software that forwards packets based on their destination IP address

Latency

how long it takes for a bit of data to travel across the network from one node or endpoint to another. It is typically measured in multiples or fractions of seconds.

many compromised passwords are stolen not by guesswork or password cracking - but by:

keyloggers that hackers manage to get onto systems using phishing or social engineering exploits

role of routing protocols

learn about other networks dynamically, exchange routing information with other devices, and connect internal and/or external networks. Their role is to determine the best path for routing. Use different means of determining the best or most optimal path to a network or network node

advantages of Star or hub-and-spoke topology

less cost and easier administration

ARP is encapsulated by a ____________ layer protocol

link

Time Division Multiplexing (TDM)

method of putting multiple data streams in a single signal by separating the signal into many segments. Each individual data stream is reassembled at the receiving end based on the timing.

Multiplexing

multiple analog or digital signals combined into one signal over a shared medium.

Frame Relay

packet-switched technology, debutted early 1990s; high-performance Data Link/Physical layer specification; successor to X.25--(much of the technology in X.25 that was used to compensate for physical errors like noisy lines has been eliminated); more cost effective than point-to-point links, typically runs at speeds of 64 Kbps up to 45 Mbps (T3); provides features for dynamic bandwidth allocation and congestion control

Frame Relay and X.25

packet-switching technologies with speeds that can range from 56 Kbps up to T3 (45 Mbps)

The router reads the IP addresses of the _______ to determine where to send the _______ .

packets, packets

logical topology

path a signal takes through the physical topology

physical topology

physical layout of the network

Dedicated (leased lines)

point-to-point or dedicated connections; pre-established WAN communications path that goes from the CPE through the DCE switch, then over to the CPE of the remote site; enables DTE networks to communicate at any time with no cumbersome setup procedures to muddle through before transmitting data; uses synchronous serial lines up to 45 Mbps. HDLC and PPP encapsulations are frequently used on leased lines

802.1X

port access protocol for protecting networks via authentication

Demarcation point

precise spot where the service provider's responsibility ends and the CPE begins

microsegmentation

process in LAN design by which every switch port connects to a single device, creating a separate collision domain per interface

What is the goal of ANSI/TIA-568 ?

provide recommended practices for the design & installation of cabling systems that will support a wide variety of existing & future services; to create a safe, reliable cabling infrastructure for all of the devices that may need interconnection

What does IEEE 802.1X do?

provides an authentication mechanism to devices wishing to attach to a LAN or WLAN.

what is "backoff" on an ethernet network?

retransmission delay that's enforced when a collision occurs

A typical home router often combines which four distinct technologies ?

router, switch, firewall, DHCP server

WPA was a :

short term workaround, or an interim solution.

some problems of unstructured cabling

someone could trip over cables and hurt themselves (lawsuit opportunity); stepping on or moving cables around over time can damage cables; other electrical devices close to the cable can create interference that confuses the signals going through the wire; unstructured cabling makes it more difficult to make changes to the network--troubleshooting nightmare!

UDP supports multicast. This makes it suitable for what?

suitable for broadcast information such as in many kinds of service discovery and shared information such as Precision Time Protocol and Routing Information Protocol.

provides datagrams

suitable for modeling other protocols such as IP tunneling or remote procedure call and the Network File System.

lack of retransmission delays

suitable for real-time applications such as Voice over IP, online games, and many protocols using Real Time Streaming Protocol.

UDP is transaction-oriented. What does this mean and what does this make it suitable for?

suitable for simple query-response protocols such as the Domain Name System or the Network Time Protocol.

master controller, the really revolutionary idea behind SDN is

that the network controller is programmable: we can write code that controls how the entire network will behave

Numerous key Internet applications use UDP, including:

the Domain Name System (DNS), where queries must be fast and only consist of a single request followed by a single reply packet, the Simple Network Management Protocol (SNMP), the Routing Information Protocol (RIP)[1] and the Dynamic Host Configuration Protocol (DHCP)

A switch keeps a record of what?

the MAC addresses of all the devices connected to it.

Fault Tolerance

the ability for a system to respond to unexpected failures or system crashes as the backup system immediately and automatically takes over with no loss of service

With hop-by-hop routing, each routing table lists, for all reachable destinations:

the address of the next device along the path to that destination: the next hop.

fault tolerance

the capability of a system to continue performing when there is a hardware failure

network enablement

the networked enablement of everyday business functions has forced enterprises to embrace the fact that physical security and cybersecurity must be treated in a unified manner.

Using perceived packet loss as feedback to discover congestion, the Transmission Control Protocol (TCP) is designed so that excessive packet loss will cause the sender to _______________________ [finish sentence]

throttle back and stop flooding the bottleneck point with data.

The router doesn't care where the packet originated. Everything is dropped into the same queue based on what ?

time the packet arrived

silo (or "to silo")

to isolate one system, process, department, etc. from others

Toll network

trunk line inside a WAN provider's network and is a collection of switches and facilities owned by the Internet service provider (ISP)

Circuit switching

two network nodes establish dedicated communications channel (circuit) through the network before the nodes may communicate; guarantees full bandwidth of channel, remains connected for duration of session. No data can transfer before end-to-end connection established. Uses dial-up modems or ISDN and is used for lowbandwidth transfers.

disadvantage of a hub

unable to differentiate between devices on network. If one computer is trying to reach another on a hub-based network, the computer will send the message to every other computer on the network, consuming bandwidth for each transfer

MAC address

unique 48-bit number that is "burned" into the network interface card adapter when it is manufactured

Optical fiber converters

used where a fiber-optic link terminates to convert optical signals into electrical signals and vice versa. You can also implement the converter as a router or switch module.

Major distinction between WAN and LAN

while you generally own a LAN infrastructure, you usually lease a WAN infrastructure from service provider.

Bluetooth

wireless technology standard for exchanging data over short distances

wireless mac filtering

you configure your router or AP so that unknown devices cannot connect to your wireless network. Very vulnerable to MAC spoofing.

(True or False) It is necessary to register private IPs with a Regional Internet Registry (RIR)

False

(True/False) EAP is an authentication protocol

False

(True/False). NAT is responsible for translating the name to an IP address.

False

(True/False). The Web server uses SMTP to deliver a Web page to a client

False

(True/False) SMTP communication between mail servers uses TCP port 24

False, SMTP communication between mail servers uses TCP port 25

Routing begins as packets come into the router for handling. The router immediately strips off _______________ and drops the resulting ______________ into a queue

*1.* Layer 2 information; *2.* the

disadvantages of fully meshed topology

*1.* Many virtual circuits are required—one for every connection between routers, which brings

three basic topologies for WAN

*1.* Star or hub-and-spoke topology >> *2* Fully meshed topology >> *3.* Partially meshed topology

Steps necessary for TCP three-way handshake

*1.* The first segment is a connection request (SYN) segment carrying the socket of the requesting host. Included is the initial sequence number for that host. *2.* The second segment is an acknowledgement (ACK) for the first host's SYN request. Included is the second host's connection request (SYN), plus the second host's own initial sequence number. *3.* The third segment is the first host's acknowledgment (ACK) for the second host's SYN request.

There are three important rules that a packet follows when it's being compared with an access list:

*1.* The packet is always compared with each line of the access list in sequential order—it will always start with the first line of the access list, move on to line 2, then line 3, and so on. *2.* The packet is compared with lines of the access list only until a match is made. Once it matches the condition on a line of the access list, the packet is acted upon and no further comparisons take place. *3.* There is an implicit "deny" at the end of each access list—this means that if a packet doesn't match the condition on any of the lines in the access list, the packet will be discarded.

primary responsibilities of transport layer protocols are

*1.* Tracking the individual communication between applications on the source and destination hosts *2.* Segmenting data for manageability and reassembling segmented data into streams of application data at the destination *3.* Identifying the proper application for each communication stream

three major characteristics of WANs

*1.* connect devices separated by a broader geographic area >> *2.* use services of carriers such as telcos, cable companies, satellite systems, and network providers. >> *3.* use serial connections of various types

Using frames achieves what two things:

*1.* prevent any single machine from monopolizing the shared bus cable. *2.* make the process of retransmitting lost data more efficient.

disadvantages of Star or hub-and-spoke topology

*1.* single point of failure. >> *2.* Central router, being a single pipe that manages all traffic, limits overall performance for access to centralized resources

There are two main types of access lists:

*Standard access lists:* These ACLs use only the source IP address in an IP packet as the condition test. All decisions are made based on the source IP address. This means that standard access lists basically permit or deny an entire suite of protocols. They don't distinguish between any of the many types of IP traffic such as Web, Telnet, UDP, and so on. *Extended access lists:* Extended access lists can evaluate many of the other fields in the layer 3 and layer 4 headers of an IP packet. They can evaluate source and destination IP addresses, the Protocol field in the Network layer header, and the port number at the Transport layer header. This gives extended access lists the ability to make much more granular decisions when controlling traffic

A 20-byte (IPv4) header contains 13 required multipurpose fields, which hold specific related object information such as application, data type and source/destination addresses.

>>> *Version*: This contains the Internet header format and uses only four packet header bits. >>> *Internet header length (IHL)*: This 32-bit field stores IP header length information. >>> *Type of service (ToS)*: This provides network service parameters. >>> *Datagram size*: This contains combined data and header length. >>> *Identification*: This 16-bit field contains a specific number for primary data identification. >>> *Flags*: This router fragment activity is controlled by three flags. >>> *Fragmentation offset*: This is a fragment identification via offset value. >>> *Time to Live (TTL)*: This contains the total number of routers allowing packet pass-through. >>> *Protocol*: This 8-bit field contains header transport packet information. >>> *Header checksum*: It checks and monitors communication errors. >>> *Source address*: It stores source IP address. >>> *Destination address*: It stores destination IP address. >>> *Options*: This is the last packet header field and is used for additional information. When it is used, the header length is greater than 32 bits.

packet switching (Odom)

A WAN service in which each DTE device connects to a telco using a single physical line, with the possibility of being able to forward traffic to all other sites connected to the same service. The telco switch makes the forwarding decision based on an address in the packet header.

ad hoc network

A group of wireless computers sharing data directly with each other without the use of a wireless access point.

C band

A range of microwave radio frequencies in the neighborhood of 4 to 8 GHz.

routing protocol

A routing protocol (for example, RIP, OSPF, or EIGRP) that advertises route information between routers, which describes how to reach specified destination networks.

DHCP snooping

A security feature on switches whereby DHCP messages on the network are checked and filtered; validates DHCP messages

connectionless

A type of Transport layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data. In telecommunication, connectionless describes communication between two network end points in which a message can be sent from one end point to another without prior arrangement. The device at one end of the communication transmits data to the other, without first ensuring that the recipient is available and ready to receive the data. The device sending a message simply sends it addressed to the intended recipient. If there are problems with the transmission, it may be necessary to resend the data several times. The Internet Protocol (IP) and User Datagram Protocol (UDP) are connectionless protocols.

Some protocols that work at DATA LINK layer 2:

Address Resolution Protocol (ARP) • Reverse Address Resolution Protocol (RARP) • Point-to Point Protocol (PPP) • Serial Line Internet Protocol (SLIP) • Ethernet (IEEE 802.3) • Token Ring (IEEE 802.5) • Wireless Ethernet (IEEE 802.11)

ARP

Address Resolution Protocol. Only in IPv4, used for discovering the link layer address (MAC) associated with a given internet layer address (IP). Resolves IP addresses to MAC addresses

T1

Also referred to as a DS1, a T1 comprises 24 DS0 circuits bundled together for a total bandwidth of 1.544 Mbps.

How does a the CSU/DSU connect to a router ?

Although the CSU/DSU connects to the service provider infrastructure using a telephone or coaxial cable, such as a T1 or E1 line, *it connects to the router with a serial cable.*

CAM

Content Addressable Memory: compares input search data (tag) against a table of stored data, and returns the address of matching data

Circuit- switched voice

Core networks also carry circuit-switched voice and T1/E1 and T3/E3 traffic. Circuit- switched voice is an older technology that guarantees a path for each voice call by setting up a dedicated path for the duration of each call

CPE

Customer Premises Equipment. Typically owned by the subscriber and located on the subscriber's premises

A(n) ______ server is responsible for assigning IP addresses.

DHCP

__________ is responsible for converting the FQDN to an IP address.

DNS

What layer (OSI) is the NIC card?

Data Link

EIA

Electronic Industries Alliance, standards & trade organization composed as an alliance of trade associations for electronics manufacturers in U.S. Developed standards to ensure equipment of different manufacturers was compatible and interchangeable. Ceased operations on February 11, 2011

Walk me through 'encapsulation'.

Encapsulation takes information from a higher layer and adds a header to it, treating the higher layer information as data. E.g., as the data moves down the stack, application layer data is encapsulated in a layer 4 TCP segment. That TCP segment is encapsulated in a Layer 3 IP packet. That IP packet is encapsulated in a Layer 2 Ethernet frame. The frame is then converted into bits at Layer 1 and sent across the local network. Data, segments, packets, frames, and bits are examples of Protocol Data Units (PDUs). NOTE The mnemonic "SPF10" is helpful for remembering PDUs: Segments, Packets, Frames, Ones and Zeroes. The reverse of encapsulation is called de-multiplexing (sometimes called deencapsulation). As the PDUs move up the stack, bits are converted to Ethernet frames, frames are converted to IP packets, packets are converted to TCP segments, and segments are converted to application data.

(True or False) In UDP the sending device receives feedback from the receiving device relating to integrity of the original message

FALSE. in UDP the device sending data never receives any type of feedback from the receiving device

stateless protocol

In computing, a stateless protocol is a communications protocol in which no information is retained by either sender or receiver, meaning that each is unaware of the state of the other. The sender transmits a packet to the receiver and does not expect an acknowledgment of receipt. A UDP connectionless session is a stateless connection because the system doesn't maintain information about the session during its life.

difference between architecture and infrastructure

Infrastructure describes the actual set of components that make up a system, while architecture describes the design of the components and their relationships. In a nutshell, a system is built on an infrastructure that has a particular architecture. For example: Many multiplayer game backends provide a client-server infrastructure. Many multiplayer game backends use a client-server architecture.

ISDN

Integrated Services Digital Network (ISDN), set of digital services that transmit voice and data over existing phone lines; offers cost-effective solution for remote users who need a higher-speed connection than analog POTS dial-up links can give them, and it's also a good choice to use as a backup link for other types of links, such as Frame Relay or T1 connections

ISDN

Integrated services digital network. A single ISDN line carries data at 128 Kbps. Although video conferences are possible at slower speeds, ISDN is considered to be the minimum for acceptable-quality video transmission.

IETF

Internet Engineering Task Force - develops and promotes voluntary Internet standards and protocols, in particular the standards that comprise the Internet protocol suite (TCP/IP)

IPsec

Internet Protocol Security: a secure network protocol suite that authenticates and encrypts the packets of data sent over an internet protocol network. It is used in virtual private networks (VPNs).

IPTV

Internet Protocol Television: delivery of television content over Internet Protocol (IP) networks in contrast to delivery through traditional terrestrial, satellite, and cable television formats

the ARP cache is used to make a network more efficient. How does it accomplish this?

It stores IP address to MAC address associations, so that the next time it needs to communicate with another device on the network it doesn' have to broadcast out on the entire network

switch

Layer 2 device that filters traffic by MAC address. Rather than sending all incoming frames to all network devices connected to it, a switch sends the frame only to the interface associated with the destination MAC address

At what layer do TCP and UDP operate?

Layer 4, Transport

can one computer have two mac addresses?

MAC Addresses are NIC specific.. Each Network Interface will have its own MAC Address. So a modern computer with support for Wired Network (LAN Interface) as well as other types of network connectivity like Wireless Network (WiFi) will obviously have multiple MAC Addresses, one for each Network interface.

What is reliable delivery in terms of internet traffic?

Method of detecting if packets were lost or if receiver did not receive an error-free transmission. The sender & receiver can agree on data that was received & the sender can find out what data needs to be retransmitted

Does UDP have a way of recovering data that may have been lost?

NO

Which is a better technology for sending data, UDP or TCP?

Neither is better or worse at sending data, but in UDP there is no verification that data was indeed received.

Which layer of the OSI model and TCP/IP model do routers work at?

Network layer of the OSI model and at the Internet layer of the TCP/IP model

what layer is ICMP?

Network, layer 3

NVRAM

Non-volatile random-access memory (NVRAM) is random-access memory that retains its information when power is turned off. This is in contrast to dynamic random-access memory (DRAM) and static random-access memory (SRAM), which both maintain data only for as long as power is applied.

How does a *datagram* differ from a packet?

Often considered synonymous to packet but there are some nuanced differences. The term datagram is generally reserved for packets of an unreliable service, which cannot notify the sender if delivery fails, while the term packet applies to any packet, reliable or not. Datagrams are the IP packets that provide a quick and unreliable service like UDP, and all IP packets are datagrams; however, at the TCP layer, what is termed a TCP segment is the sometimes necessary IP fragmentation of a datagram, but those are referred to as "packets"

The 802.11 - 2007 standard specifies what two different methods of authentication:

Open System authentication and Shared Key authentication.

OC-3

Optical Carrier (OC) 3 uses fiber and is made up of three DS3s bundled together. It's made up of 2,016 DS0s and avails a total bandwidth of 155.52 Mbps.

OC-12

Optical Carrier 12 is made up of four OC-3s bundled together and contains 8,064 DS0s for a total bandwidth of 622.08 Mbps.

OC-192

Optical Carrier 192 is four OC-48s and contains 129,024 DS0s for a total bandwidth of 9953.28 Mbps.

OC-48

Optical Carrier 48 is made up of four OC-12s bundled together and contains 32,256 DS0s for a total bandwidth of 2488.32 Mbps.

At what layer of the OSI model does encryption and decryption of data for secure transmission take place?

Presentation (layer 6)

Which cipher did WPA2's AES replace ?

RC4

Partially meshed topology

Reduces number of routers w/in a network that have direct connections to all other routers in the topology. Not all routers are connected to all other routers. But still provides more redundancy than a typical hub-and-spoke design. Considered

T3

Referred to as a DS3 a T3 comprises 28 DS1s bundled together, or 672 DS0s, for a bandwidth of 44.736 Mbps.

Route poisoning

Route poisoning is a method of preventing a network from sending packets through a route that has become invalid.

what is meant by TCP being "self-throttling"

TCP itself implements the congestion control

Between UDP and TCP, the one that is a connection-oriented protocol is _____________. The connectionless protocol is_____________.

Transmission Control Protocol (TCP) is connection-oriented. User Datagram Protocol is connectionless(UDP).

TIA

The Telecommunications Industry Association (TIA) is accredited by the American National Standards Institute (ANSI) to develop voluntary, consensus-based industry standards for a wide variety of Information and Communication Technologies (ICT) products, and currently represents nearly 400 companies.

Describe what the Transport Layer does to data it receives from the Application Layer

The Transport layer breaks that data into chunks, adding port numbers and sequence numbers, creating the TCP segment. The Transport layer then hands the TCP segment to the Internet layer, which, in turn, creates the IP packet.

collision domain

The portion of an Ethernet network in which collisions could occur if two nodes transmit data at the same time

packet switching

The routing and transferring of data by means of addressed packets so that a channel is occupied during the transmission of the packet only, and upon completion of the transmission the channel is made available for the transfer of other traffic

Split horizon

This feature of a distance-vector routing protocol prevents a route learned on one interface from being advertised back out of that same interface.

E1

This is the European equivalent of a T1 and comprises 30 DS0 circuits bundled together for a bandwidth of 2.048 Mbps.

Digital Signal 0 (DS0)

This is the basic digital signaling rate of 64 Kbps, equivalent to one channel. Europe uses the E0 and Japan uses the J0 to reference the same channel speed. Typical to T-carrier transmission, this is the generic term used by several multiplexed digital carrier systems and is also the smallest-capacity digital circuit. One DS0 = One voice/data line.

Star or hub-and-spoke topology

This topology features a single hub that provides access from remote networks to a core router

Why was classless interdomain routing (CIDR) created?

To allow an address class size to meet an organization's need.

(True of False) TCP is not used to broadcast messages to multiple network recipients.

True

(True or False) Most residential network routers receive a globally unique IP address within the ISP network.

True

(True or False) UDP does not guarantee that the packet arrives at its destination.

True

(True or False) You cannot use repeaters on analog signals

True

(True/False) Bridges reduce collisions by creating a separate collision domain on either side of the bridge

True

(True/False) Packet-switching protocols for T-Carrier and OC lines are functionally identical to routable network protocols like TCP/IP.

True

(True of False) Streaming media, real-time multiplayer games and voice over IP (VoIP) are examples of applications that often use UDP.

True, In these particular applications, loss of packets is not usually a fatal problem

(True/False) Routing protocols do not send packets across the network

True. Routing protocols DO NOT send packets across the network. Their role is to determine the best path for routing.

What do NTP and SNTP stand for and what is their function?

Two popular applications that use UDP are Network Time Protocol (NTP) and his lightweight little brother, Simple Network Time Protocol (SNTP). These protocols synchronize the clocks of devices on a network. Computers need to use the same time so things like Kerberos authentication work properly. If a device requires NTP/SNTP, you will be able to enter the IP address for an NTP/SNTP server. NTP/SNTP uses port 123.

Which transport layer protocol does DNS use: UDP or TCP ?

UDP

drawback of UDP

UDP does not have a way to recover lost data or reorder data that has been received out of order

UDP

User Datagram Protocol, alternative communications protocol to TCP, used primarily for establishing low-latency & loss-tolerating connections between applications on the internet.

UDP

User Datagram Protocol. Used when guaranteed delivery of each packet is not necessary; uses best-effort delivery mechanism; is a connectionless protocol; lower bandwidth overhead and latency; ideal for applications in which perceived latency is critical--gaming, voice, video, which can suffer some data loss w/out adversely affecting perceived quality.

ARP poisoning

attacker changes the Media Access Control (MAC) address and attacks an Ethernet LAN by changing the target computer's ARP cache with a forged ARP request and reply packets. attacks can redirect traffic through an attacker's system by sending false MAC address updates. VLAN segregation helps prevent the scope of ARP poisoning attacks within a network.

datagram

basic transfer unit associated with a packet-switched network; typically structured in header & payload sections; provide a connectionless communication service across a packet-switched network. Delivery, arrival time, & order of arrival of datagrams need not be guaranteed by the network. The term datagram is

IEEE 802.11

Wireless Ethernet standard more commonly known as Wi-Fi

OSI model is called:

a multilayer switch (MLS)

Dynamic Host Configuration Protocol

a network management protocol used on UDP/IP networks whereby a DHCP server dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks.[1] A DHCP server enables computers to request IP addresses and networking parameters automatically from the Internet service provider (ISP), reducing the need for a network administrator or a user to manually assign IP addresses to all network devices.[1] In the absence of a DHCP server, a computer or other device on the network needs to be manually assigned an IP address, or to assign itself an APIPA address, which will not enable it to communicate outside its local subnet.

IEEE 802.3u

a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s (the earlier Ethernet speed was 10 Mbit/s). Of the Fast Ethernet standards, 100BASE-TX is by far the most common.

Failover

a specific type of fault tolerance, occurs when a redundant storage server offers an exact replica of the real-time data, and if the primary server crashes, the users are automatically directed to the secondary server or backup server

subnet mask

a string of ones followed by some number of zeroes, always totaling exactly 32 bits, typed into every TCP/IP host. Divides the IP address into network address and host address

IEEE 802.3

a working group and a collection of Institute of Electrical and Electronics Engineers (IEEE) standards produced by the working group defining the physical layer and data link layer's media access control (MAC) of wired Ethernet. This is generally a local area network (LAN) technology with some wide area network (WAN) applications. Physical connections are made between nodes and/or infrastructure devices (hubs, switches, routers) by various types of copper or fiber cable.

802.11 wireless networking is most often implemented at what layer?

access

What is the purpose of the Logical Link Control (LLC) layer in the OSI model?

acts as an interface between the media access control (MAC) sublayer and the network layer; provides standard interface for whatever network protocol is being used; provides an abstraction layer so that the network protocol does not need to be programmed to communicate with all of the possible MAC level protocols (Ethernet, Token Ring, WLAN, FDDI, etc)

Summarization, also called route aggregation:

allows routing protocols to advertise many networks as one address to reduce the size of routing tables on routers to save memory, which also shortens the amount of time IP requires to parse the routing table when determining the best path to a remote network.

Packet switching

allows you to share bandwidth with other companies to save money; designed to look like a leased line yet it charges you less, like circuit switching does; Packet switching will only really work for you if your data transfers are bursty, not continuous

rogue access point

any unauthorized Wi-Fi device that is not under the management of the proper network administrators

link aggregation

applies to various methods of combining (aggregating) multiple network connections in parallel in order to increase throughput beyond what a single connection could sustain, and to provide redundancy in case one of the links should fail. *INCREASE THROUGHPUT* and *PROVIDE REDUNDANCY*