Term
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Definition
| Hyper Text Transfer Protocal, and is an application protocol for distributed, collaborative, hypermedia informations systems. HTTP is the foundation of data communication of the WWW |
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Term
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Definition
| HTML is Hyper Text Marup Langauge and it is a representation standard that specifies the syntax of a webpage |
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Term
| Is HTTP stateful or stateless? |
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Definition
| It is stateless, meaming server maintains no information about past client requests. Once the requested information is given, the connection is broken |
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Term
| Non-Persistent HTTP vs Persistent HTTP |
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Definition
Nonpersistent is at most one object is sent over a TCP connection. It usses HTTP 1.0 and uses nonpersistent HTTP
Persistent sends multiple objects over a single TCP connection between client and server. It uses HTTP 1.1 uses persisten connections in default mode. |
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Term
| 2 Modes of FTP - active VS passive |
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Definition
Active users connect from random ports on a file transfer client to port 21 on the server. It sends the PORT command, specifying what client-side port the server should conenct to. This port will be used later on the data chnnel and is different from the port used in this step for the command channel. The server connects from port 20 to the cleint port designated for the data channel. Once connection is established, file trasnfers are then made through these clietn and serve ports.
Passive clients connect from a random port to port 21 on the server and issues the PASV commadn. Ther server replies, indicating which random port it has opened for data transfer. The client connects from another random port to the random port specified in the server's response. Once connection is established, data transfers are made through tehse client and server ports. |
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Term
| What is the delivery protocol for email system? |
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Definition
| SMPT, or Simple Mail Transfer Protocol |
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Term
| What are the retrieveal protocols for email system? |
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Definition
| POP, or Post Office Protocol, and IAMP, or Internet Mail Access Protocol |
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Term
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Definition
| Is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems |
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Term
| What is MIME (Multi-purpose Itnernet Mail Extensions) |
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Definition
An additional lines in message header declare MIME contet type.
[image]
MIME allows for: Text in characters sets other than ASCII, Non-text attachments, Message bodies with multiple parts, and Header information in non-ASCII character sets |
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Term
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Definition
| In forward DNS, you give it a domain example www.csuchico.edu and get an IP back 132.241.82.63. In reverse DNS you give it an IP 132.241.82.63 and get a domain back www.csuchico.edu |
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Term
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Definition
| it uses the MX record. When you send an email xxx@csuchico.edu, your email server will lookup MX records of "csuchico.edu" domain and get the IP addresses of the email servers |
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Term
| DNS server load balancing |
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Definition
| DNS server load balancing is having multiple servers that handle DNS requests so the servers do not get flooded and crash |
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Term
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Definition
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Term
| Recursive VS Iterative servers |
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Definition
Itterative simplest mode for the server is non-recursive, since it can answer queires using only local information: the response contains an error, the answer, or referral to some other server "closer" to the answer. All name servers must implement non-recursive queries.
Recursive: The simplets mode for the client is recursive, since in this mode the name server acts in the rolve of a resolver and returns either an error or the answer, but never refferals. This service is optional in a name server, and the name server may also choose to restrict the clients which can use recursive mode |
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Term
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Definition
root hints provides a lsit of preliminary resource records that can be used by the DNS service to locate other DNS server that are authoritative fo rthe root of the DNS domain namespace
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Term
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Definition
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Term
| Data Communication Componets |
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Definition
Source Data -> Digitization A-to-D -> Source Encoder -> Channel Encoder - > Transmission System -> Channel Decoder -> Source Decoder -> D-to-A Converter -> Sink of Data
[image] |
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Term
| Signal representation in time domain and frequency domain |
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Definition
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Term
| What is the main idea of Fourier's Theorem? |
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Definition
| Any signal can be constructed by combining a series of sinusoidal signals |
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Term
| Why do we limit the bandwith of voice signal to 300-3400HZ (nominally 4kHZ inlcuding som guard bands?) |
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Definition
| So we can mix many voices on one UTp(T1 Carrier) or line |
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Term
| What is the relationship between Signal BW and Channel BW |
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Definition
| Signal Bandwith is similar to the voume of water flowing through a pipeline while channel bandwidth is the volume of water the pipeline can flow. |
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Term
| How do we decide the bandwith of a given medium? |
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Definition
| Attenuation: strength of output signal / strength of input signal |
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Term
| What is bit synchronization? |
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Definition
Bit synchronization is when the data signals with N-bites is sent to a reciever with the same N-bits and all bits rising and fallng edges line up. Below is an example of an error in bit synchronization
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Term
| Why do we need Source Encoding? |
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Definition
| As a longer string of 0's and 1's are sent bit synchronization becomes more of a problem. Source encoding prevents possible issues of bit synchronization. |
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Term
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Definition
| 4B/5B maps groups of four bits on to groups of 5 bits, with a minimum density of 1 bits in the output. When NRZI-encoded, the 1 bits provide necessary clock transistions for the reciever. For example, a run of 4 bits such 0000 contains no transitions and the causes clocking problems for the reciever. 4B/5B solves this problem by assigning each block of 4 consecutive bits an equivalent word of 5 bits. These 5 bit words are pre-determined in a dictionary and they are chosen to ensure that there will be at least two transitions per block of bits. |
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Term
| Minimum sampling frequency |
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Definition
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Term
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Definition
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Term
| What is run-lenght encoding? |
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Definition
It is when you take a data source of N-characters and make it smaller by writing the amount of consecutive letters and then the letter itself. For example
Data Source: 67 characters
WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW
Can be written in 18 characters as
12W1B12W3B24W1B14W |
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