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NAME :- RIDHAM

ROLL NO

:-RTB903A02

REG NO:- 10905372

CODE :- CAP 306

HOME WORK :- 4

Q1 :- Classify the following classes into class A, B, C, D, E :-

a) 197.18.10.201 :- Class C

b) 170.78.90.121 :- Class B

c) 248.172.16.109 :- Class D

d) 11001100.00001111.10101010.00000011 :- i.e 204.15.170.3 :- Class C

Q2:- Which is the better classless addressing or classful addressing? Explain with

example?

Ans:- ClassFul addressing means it will not carry the routing mask information while

routing updates or routing advertisements. it will carry just only the ip-address

information's. It will assume just default mask information's. where as classless

addressing routing protocols will carry the subnet mask information's while doing the

routing updates or routing advertisements.

Example of classful protocol : --class-A 255.0.0.0

Class-B 255.255.0.0

Class-C 255.255.255.0

So classful routing protocols will not support the VLSM and Supernetting

Example of classful routing protocols is

1. RIP V1

2. IGRP

Example of classless protocol :-RIP V2

EIGRP

OSPF

Q3:- In symmetric key cryptography how many keys are needed if Alice and Bob want

to communicate with each other?

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Ans:- In the symmetric key cryptography a single key is used in bidirectional

communication . If Alice and Bob want to communicate with each other a secret key

encryption /decryption the same key is used by both the parties.

The sender uses this key and encryption algorithm to encrypt data. the

receiver uses the same key and the corresponding decryption algorithm to decrypt the data.

Part -B

Q4:- In a symmetric key cryptography , if person in a group of 10 people need to

communicate with every other person in another group of 10 people how many

secret keys are needed?

Ans:- If person in a group of 10 people need to communicate with every other person in

another group of 10 people then 45 secret keys are needed.

i.e n * (n-1)/2

10*(10-1)/2 =>45

Q5:- Find the block of address assigned to your organization or institution?

Ans:- The organization network is connected to the Internet via a router. The router has two

addresses. One belongs to the granted block. The other belongs to the network that is at the

other side of the router.

We call the second address x.y.z.t/nbecause we do not knowanything about the network it is connected to at the other side. All messages destined for

addresses in the organization block (205.16.37.32 to 205.16.37.47) are sent, directly or

indirectly, tox.y.z.t/n.

We say directly or indirectly because we do not know the structure

of the network to which the other side of the router is connected.

Suppose an organization is given the block 17.12.40.0/26, which

contains 64 addresses. The organization has three offices and needs to divide the addresses

into three subblocks of 32, 16, and 16 addresses. We can find the new masks by using the

following arguments:----

1. Suppose the mask for the first subnet is n1, then 232- n1 must be 32, which means

that n1 =27.

2. Suppose the mask for the second subnet is n2, then 232- n2 must be 16, which

means that n2 = 28.

3. Suppose the mask for the third subnet is n3, then 232- n3 must be 16, which means

that n3 =28.

This means that we have the masks 27, 28, 28 with the organization mask being 26.

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Q6:- Some people argue that we can consider the whole address space as one single

block in which each range of address is a sub block to this single block. Elaborate on

this idea what happens to sub netting if we accept this concept?

Ans:- A subnetwork, is a logically visible subdivision of an IP network. The practice of

creating subnetworks is called subnetting.

All computers that belong to a subnet are addressed with a common, identical, most-

significant bit-group in theirIP address. This part of the address is known as the routing

prefix or network number. The size of the routing prefix may be indicated using CIDR

notation or through specification of a subnet mask

The benefits of subnetting vary with each deployment scenario. It may use address space

more efficiently, may enhance routing efficiency, or have advantages in network

management when subnetworks are administratively controlled by different entities in a

larger organization. Subnets may be arranged logically in a hierarchical architecture,

partitioning the organization's network address space into a tree-like routing structure.

While it may improve network performance, subnetting increases routing complexity, since

each locally connected subnet must be represented by a separate entry in the routing tables of

each connected router. However, by careful design of the network, routes to collections of

more distant subnets within the branches of a tree-hierarchy can be aggregated by single

routes where as address space logically divided into sections, called segments. To access a

particular memory location, a program must specify both the segment number and

the offset within that segment. In contrast, a flat address space consists of simple memory

addresses that start at 0 and increment to the maximum address..

http://en.wikipedia.org/wiki/IP_networkhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/CIDR_notationhttp://en.wikipedia.org/wiki/CIDR_notationhttp://en.wikipedia.org/wiki/Routing_tablehttp://www.webopedia.com/TERM/A/address_space.htmlhttp://www.webopedia.com/TERM/L/logical.htmlhttp://www.webopedia.com/TERM/O/offset.htmlhttp://en.wikipedia.org/wiki/IP_networkhttp://en.wikipedia.org/wiki/IP_addresshttp://en.wikipedia.org/wiki/CIDR_notationhttp://en.wikipedia.org/wiki/CIDR_notationhttp://en.wikipedia.org/wiki/Routing_tablehttp://www.webopedia.com/TERM/A/address_space.htmlhttp://www.webopedia.com/TERM/L/logical.htmlhttp://www.webopedia.com/TERM/O/offset.html

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