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+2 votes
if the subnet mask is

which of the following can be DBA of subnet.




asked in Computer Networks by Junior (819 points) | 721 views

2 Answers

0 votes
Option B
answered by Active (5.1k points)
Hey why not C? Isn't both B and C right?
Given subnet mask is  11111111.11111111.11111111.11100000

The first 27 bits belong to the network here .Free bits are last 5 bits which are Host id bits. To get DBA we need to make the host bits all 1's .

Here host bits are 5 . so make allo of them as 1. This gives 11111=31
But doesn't the subnet mask the network in subnets this case into - 31 and - 63 and so on...... ?
As u said to get 63 we need  --111111 but here the first 3 bits are fixed . you cannot do anything on the first 3 bits .So we can only use the remaining 5 bits
What I mean is if a subnet mask is applied on, it means that the ip address can be subnetted into groups of 32 ip's (2^5)
In this case will have has DBA
In the case of, will be the DBA

Correct me if I'm wrong
yes , u r correct . It was my mistake . Thank you Bro :)
0 votes
Answer is option C). will be written as 11111111.11111111.11111111.11100000

First three bits are netid and next 5 is used for hosts.

a) : 15 is 00001111 .In dba all host bits are 1. As only first three are netid all bits cannot be 1 here.

B) : 31 is 00011111. It is DBA for all network.Not only for particular subnet.

C) 63 is 00111111 .This is DBA for neid 001 ANd where all host bits are 1.
answered by Active (1.2k points)

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