Anna University Coimbatore 2009 B.E Electronics

be transformed back to the original data.
8. Why is an application such as POP needed for electronic messaging?
Workstations interact with the SMTP host, which receives the mail on behalf
of every host in the organization, to retrieve messages by using a client-server
protocol such as Post Office Protocol, version 3(POP3). Although POP3 is used to
download messages from the server, the SMTP client still needed on the desktop to
forward messages from the workstation user to its SMTP mail server.
9. provide the format of HTTP request message.
10. provide the format of HTTP response message.
11. Write down the 3 kinds of WWW documents.
The documents in the WWW can be grouped into 3 broad categories:
static, dynamic and active.
Static: Fixed-content documents that are created and stored in a server.
Dynamic: Created by web server whenever a browser requests the document.
Status Line
Headers
A Blank Line
Body
(present only in
a few messages)
Request Line
Headers
A Blank Line
Body
(present only in
a few messages)
Active: A program to be run at the client side.
12. What is the purpose of HTML?
HTML is a computer language for specifying the contents and format of a
web document. It allows additional text to include codes that describe fonts, layouts,
embedded graphics and hypertext links.
13. describe CGI.
CGI is a standard for communication ranging from HTTP servers and executable
programs. It is used in crating dynamic documents.
14. Name 4 factors needed for a secure network.
Privacy: The sender and the receiver expect confidentiality.
Authentication: The receiver is sure of the sender' s identity and that an imposter has
not sent the message.
Integrity: The data must arrive at the receiver exactly as it was sent.
Non-Reputation: The receiver must able to prove that a received message came from
a specific sender.
15. How is a secret key various from public key?
In secret key, the identical key is used by both parties. The sender uses this key
and an encryption algorithm to encrypt data; the receiver uses the identical key and the
corresponding decryption algorithm to decrypt the data.
In public key, there are 2 keys: a private key and a public key. The private
key is kept by the receiver. The public key is announced to the public.
16. What is a digital signature?
Digital signature is a method to authenticate the sender of a message. It is

Earning:   Approval pending.