Chapter 1 Flashcards
How many layers in ISO OSI model?
7
Each layer provides ……. for the layer directly above it?
Services
What is the name of layer 7
Application layer
Some application layer protocols:
HTTP, SMTP, POP3
Example of a HTTP request:
GET /index.htm HTTP/1.1
Host: www.xx.co.za
How is header information separated from payload in a server response to a HTTP request?
With a blank line
Http/1.1 200 OK
Date: ….
Content-length: 5667
Content-type: text/html
<html>
<head>
.....
</head></html>
What is layer 6?
Presentation layer
What was the problem with displaying/representing data?
Not all computer used the same representation (ASCII, EBCDIC, UTF)
How does a browser specify which encodings it will accept?
Accept-Charset: iso-8859-2, unicode-1-1
What would happen if the server cannot use one of the encodings specified?
It should return a 406 error.
What are some presentation standards?
XML, HTML, MIME, ARPA Internet Text Messages
Can the presentation layer be included in the application layer?
Yes. Since HTML encoded email may also be sent using SMTP
What is layer 5?
Session layer
What does the session layer usually refer to in modern networks?
Sequence of events in application protocol
What is layer 4?
Transport layer
Which layer provides process-to-process communication?
Layer 4
What type of communication does Layer 4 provide?
process-to-process
Does a end-to-end connection have to be reliable?
No, it is not a requirement.
What is good and bad about reliable end-to-end connection?
Good:
Retransmit parts of message that has been lost, “throttling”
Bad:
Is slower
What layer is layer 3?
Network Layer
What service does the network layer provide?
Routing
How does a network know where and how to route?
It uses a routing table, usually indicates next router on path
What is Layer 2?
Data link layer
On what layer is the system that determines routes in a routing table?
7 ( RIP )
