Routing Tables Network Layer

Question

Please tell me which interface will be selected for the above IP address

Answer 1

Given ip after anding with subnet masks of interface a,b,c,d will give NID as 192.168.24.0 in all the cases.

In this situation, the rule is to  select the subnet mask with longest runs of 1's.

So,interface C will be selected because subnet mask 255.255.255.224 has longest runs of 1's.

Ans: Interface C

Comments

Thankyou

But I am thinking that the interface will be "D" because it it matching longest prefix to given IP address

I mean Interface D has all 0 's in last octet in Subnet mask address and the last octet of IP address is

00001010. So i thought that first four zeros in Subnet Mask and IP address are matching and generally router selects the interface with longest prefix match. So i think answer as "D"

Please correct me if i got anything wrong!

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In case of multiple matches we have to select longest mask bit.

Hence, interface C will be selected.

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Why should we choose longest

Subnet mask bit?

Answer 2

IP 198.168.24.10  when taken 'AND' with subnetmasks ,each one gives the same resultant NID.

 we select subnet mask with greater no of one's in it. so Option 'C' will be the answer.