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Networking Chapters 1 + 2
Study Guide for Test
71
Computer Networking
Undergraduate 2
02/24/2014

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Term
What does IETF stand for?
Definition
Internet Engineering Task Force
Term
What does RFC stand for?
Definition
Request for Comments
Term
What does FDM stand for?
Definition
Frequency-division Multiplexing
Term
What does Wi-Fi stand for?
Definition
A slang way of saying Wireless Local Area Network. (WLAN) Some say Wi-fi stands for wireless fidelity but it doesn't actually stand for anything.
Term
What does WAN stand for?
Definition
Wide Area Network
Term
What does FTP stand for?
Definition
File Transfer Protocol
Term
What does UDP stand for?
Definition
User Datagram Protocol
Term
What does SMTP stand for?
Definition
Simple Mail Transfer Protocol
Term
What does DNS stand for?
Definition
Domain Name System
Term
What is a protocol?
Definition
A protocol controls the sending and receiving of information within the internet. Run on end-systems.
Term
What is the difference between a host system and an end-system?
Definition
They are both the same thing.. Includes PCs, workstations, Web Servers, mail servers, Internet connected PDAs, WebTVs, etc.
Term
Name 5 protocols
Definition
TCP, IP, UDP, SMTP, FTP, HTTP, Skype, 802.11
Term
What does TDM stand for?
Definition
Time Division Multiplexing
Term
What are the 5 layers in the Internet?
Definition
1. Application
2. Transport
3. Network
4. Data Link
5. Physical
Term
What does store-and-forward mean?
Definition
The entire packet must arrive at router before it can be transmitted on next link
Term
What's the difference between packet switching and circuit switching?
Definition
-Packet switching allows more users to use network.
-Circuit switching has circuit-like (guaranteed) performance
-Packet switching is simpler, no call setup
-Packet switching has resource sharing
-Packet switching has packet delay and loss. Needs more work, protocols needed for reliable data transfer, congestion control
Term
How do packet loss and packet delay occur?
Definition
-When packet arrival rate to link (temporarily) exceeds output link capacity.
-Packets queue, wait for turn.
Term
What is queueing delay?
Definition
-Time waiting at output link for transmission.
-Depends on congestion level of router.
Term
What is nodal processing delay?
Definition
-Checking for bit errors.
-Determine output link.
-Typically < msec
Term
What is transmission delay?
Definition
Time needed to transmit L-bit packet into link
-L:packet length (bits)
-R:link bandwidth (bps)
-dtrans = L/R
Term
What is propagation delay?
Definition
-d:length of physical link
-s:propagation speed in medium (~2x10^8 m/sec)
-dprop = d/s
-Very different from transmission delay calculation.
Term
What is the traceroute program?
Definition
Provides delay measurement from source to router along end-end Internet path towards destination.
Term
What does the traceroute program output?
Definition
for all i(routers):
-sends three packets that will reach router i on path towards destination
-router i will return packets to sender
-sender times interval between transmission and reply.
(Outputs 3 different delay measurements from every router between two host machines)
Term
What is end-to-end throughput?
Definition
End-to-end throughput is the rate (bits/time unit) at which bits transferred between sender/receiver(One end to another end).
Term
What is the instantaneous end-to-end throughput?
Definition
rate at given point in time
Term
What is the average end-to-end throughput?
Definition
Rate over longer period of time.
If it takes T seconds for a host to receive a file with F bits, then the avg throughput is F/T bps.
Term
Explain the application layer.
Definition
Supporting network applications.
-Uses FTP, SMTP, and HTTP
Term
Explain the transport layer.
Definition
Process-process data transfer.
-TCP, UDP
Term
Explain the network layer.
Definition
Routing of datagrams from source to destination.
-IP, routing protocols
Term
Explain the Data link layer.
Definition
Data transfer between neighboring network elements.
-Ethernet, 902.111 (WiFi), PPP
Term
Explain the Physical layer.
Definition
bits "on the wire"
Term
What layer's packets are called messages?
Definition
Application
Term
What layer's packets are called segments?
Definition
Transport
Term
What layer's packets are called datagrams?
Definition
Network
Term
What layer's packets are called frames?
Definition
Link
Term
What are typical protocols for the application layer?
Definition
FTP, SMTP, or HTTP
Term
What are typical protocols for the transport layer?
Definition
TCP or UDP
Term
What is link bandwidth?
Definition
Also called Link Transmission Rate, how fast data is pushed to the communication link.
Term
Bandwidth vs. end-to-end throughput
Definition
Bandwidth describes data transmission capacity of a communication link, but end-to-end throughput describes the average rate at which data is transmitted between the sender (one end) and the receiver (the other end).
Term
What are the possible Application Architectures, or structure of applications using the internet?
Definition
-client-server
-peer-to-peer (P2P)
Term
What is client-server architecture?
Definition
Server: Always-on host, permanent IP address, data centers for scaling.
Clients: Communicate with server, may be intermittently connected, may have dynamic IP addresses, do not communicate directly with each other. Facebook, YouTube, Gmail.
Term
What is P2P Architecture?
Definition
There is no always-on server, arbitrary end systems directly communicate from eachother, peers request service from other peers, provide service in return to other peers, peers are intermittently connected and change IP addresses. BitTorrent, uTorrent, Bitcoin
Term
What is self scalability?
Definition
In p2p architecture, new peers bring new service capacity, as well as new service demands.
Term
What's the difference between Transmission Control Protocol(TCP) services and User Datagram Protocol User Datagram Protocol(UDP) services?
Definition
Transmission Control Protocol(TCP) provides a reliable transport, flow control, and congestion control. User Diagram Protocol(UDP) does not provide any of these.
Term
What services does Transmission Control Protocol(TCP) provide?
Definition
TCP provides reliable transport, flow control, congestion control, does not provide, and is connection-oriented.
Term
What services does User Datagram Protocol(UDP) provide?
Definition
UDP provides unreliable data transfer.
Term
Why use UDP?
Definition
UDP is simpler so some systems that have limited capabilities (e.g. embedded systems prefer to use UDP)

UDP has less latency: the cost of establishing a TCP connection is sometimes excessive: If I just want to urgently send you a packet, I don't want to lose time of establishing a TCP connection.

The retransmission mechanism of TCP can be a nuisance for nearly real time systems: If I transmit video, I don't want the image to freeze while TCP is retransmitting. If a video packet is lost, that's a pity, you will have some pixelation of your image, but you will soon get the next UDP packet and the image will recover.
Term
What kind of transport layer protocol does HTTP(streaming multimedia) use?
Definition
TCP or UDP
Term
What kind of transport layer protocol does SMTP(e-mail) use?
Definition
TCP
Term
What kind of transport layer protocol does Telnet(remote terminal access) use?
Definition
TCP
Term
What kind of transport layer protocol does HTTP(Web) use?
Definition
TCP
Term
What kind of transport layer protocol does FTP(file transfer) use?
Definition
TCP
Term
What kind of transport layer protocol does SIP, RTP, proprietary(i.e Skype)[Internet telephony] use?
Definition
TCP or UDP
Term
What are some transport service requirements?
Definition
File-transfer, Email, and Web must be reliable so they use TCP. Congestion control and flow control are also necessary for Email and file-ttransfer. UDP would be ideal for multimedia applications, because a video will freeze using TCP when it has to retransmit for a package, but UDP will only pixelate the image till the next packet is sent.
Term
Hypertext Transport Protocol(HTTP) port number?
Definition
80
Term
File Transfer Protocol(FTP) port number?
Definition
21
Term
What 2 connections does FTP use?
Definition
2 TCP connections: a control connection(transmitting commands) and a data connection(transmitting data)
Term
What does Simple Mail Transfer Protocol(SMTP) do?
Definition
Runs between mail servers and between mail client and mail server for message sending.
Term
What do Mail Access Protocols do?
Definition
Between mail server and mail client for message retrieving, using Post Office Protocol(POP3), Internet Mail Access Protocol(IMAP), and Hypertext Transfer Protocol(HTTP)
Term
What important services does Domain Name Server(DNS) provide?
Definition
-hostname to IP address translation
-host aliasing
-mail server aliasing
-load distribution
Term
What are the four types of Domain Name System(DNS) records?
Definition
-A
-CNAME
-NS
-MX
Term
What is nslookup?
Definition
Name Server Lookup. Usable on most PCs to obtain name server information for Domain Name System(DNS) by querying Domain Name System(DNS).
Term
C:\> nslookup
Default Server: resolver1.opendns.com
Address: 208.67.222.222

\>

What is this showing?
Definition
This nslookup shows the DNS server configured on the PC in use for look-ups.
Term
What is HTTP Response Status Code: 200?
Definition
200 = OK
-Request succeeded, requested object later in this msg
Term
What is HTTP Response Status Code: 202?
Definition
202 = Accepted
-The request has been accepted for processing, but the processing has not been completed.
Term
What is HTTP Response Error Code: 301?
Definition
302 = Moved Permanently
-Requested object moved, new location specified later in this msg (Location:)
Term
What is HTTP Response Error Code: 304?
Definition
304 = Not Modified
If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server SHOULD respond with this status code.
Term
What is HTTP Response Error Code: 403?
Definition
403 = Forbidden
The server understood the request, but is refusing to fulfill it. Authorization will not help and the request SHOULD NOT be repeated.
Term
What is HTTP Response Error Code: 404?
Definition
404 = Not Found
-Requested document not found on this server.
Term
What are cookies for?
Definition
-authorization
-shopping carts
-recommendations
-user session state(Web e-mail)
Term
How does the cookie mechanism work?
Definition
They permit sites to learn a lot about you. You may supply names and e-mail to sites.
Supporting users have an ad free experience!