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7/29/2019 NP Lab Viva

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1. Draw TCP and UDP Header.


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2. Difference between IPV4 and IPV6?

3. What is Cookie?When a client requests a Web page, the server can supply additional information

along with the requested page. This information may include a cookie, which is a small

(at most 4 KB) file (or string). Browsers store offered cookies in a cookie directory on

the client's hard disk unless the user has disabled cookies. Cookies are just files or

strings, not executable programs. In principle, a cookie could contain a virus, but since

cookies are treated as data, there is no official way for the virus to actually run and do

damage. However, it is always possible for some hacker to exploit a browser bug to

cause activation.


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4. Draw the Web Model?

5. Difference between Static and Dynamic Web document?Static Websites

A static site is a website that is written entirely using HTML. Each web page is a

separate document and there are no databases or external files that are drawn upon.

This means that the only way to edit this type of website is to go into each page and editthe HTML. So you would have to do it yourself using a web page editor such as FrontPage

or Dreamweaver, or pay your web developer to make updates for you.

Dynamic Websites

A dynamic website is written using more complex code such as PHP or ASP

and has a greater degree of functionality. For instance, many dynamic websites can be

controlled by a content management system. This means that you will potentially be able

to make updates without needing any knowledge of HTML or any website software.

Each page of a dynamic website is generated from information stored in a database or

external file. And the content management system that you may use to maintain your

website directly modifies this stored information.

6. Difference between SMTP and POP?SMTP: Within the Internet, e-mail is delivered by having the source machine

establish a TCP connection to port 25 of the destination machine. Listening to this port is

an e-mail daemon that speaks SMTP (Simple Mail Transfer Protocol). This daemon

accepts incoming connections and copies messages from them into the appropriate

mailboxes. If a message cannot be delivered, an error report containing the first part of

the undeliverable message is returned to the sender. SMTP is a simple ASCII protocol.

POP3 begins when the user starts the mail reader. The mail reader calls up theISP (unless there is already a connection) and establishes a TCP connection with the


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message transfer agent at port 110. Once the connection has been established, the POP3

protocol goes through three states in sequence:

1. Authorization.

2. Transactions.

3. Update.

The authorization state deals with having the user log in. The transaction state deals withthe user collecting the e-mails and marking them for deletion from the mailbox. The

update state actually causes the e-mails to be deleted.

7. Define User Agent and Transfer Agent?The user agents allows people to read and send e-mail, and the message transfer

agents, moves the messages from the source to the destination. The user agents are local

programs that provide a command-based, menu-based, or graphical method for

interacting with the e-mail system. The message transfer agents are typically system

daemons, that is, processes that run in the background. Their job is to move e-mailthrough the system.

8. What is IP address and Classes?Every host and router on the Internet has an IP address, which encodes its

network number and host number. The combination is unique: in principle, no two

machines on the Internet have the same IP address. All IP addresses are 32 bits long and

are used in the Source address and Destination address fields of IP packets.

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