https://www.indiabix.com/networking/subnetting/004004

Question

	Using the following illustration, what would be the IP address of E0 if you were using the eighth subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. The zero subnet should not be considered valid for this question.
	A. 192.168.10.142 B. 192.168.10.66 C. 192.168.100.254 D. 192.168.10.143 E. 192.168.10.126

Answer 1

Subnet Id of 8th subnet :-  192.168.10.   0111 0000  

Broad cast Id of 8th Subnet : 192.168.10.   0111 1111

Last useful ip address for E0 router Interface will be : 192.168.10.   0111 1110 ---->192.126.10.126

So Option D is Correct .

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Edit :

They have mentioned that 0^th subnet will not be a  valid subnet so we start from 1

Subnet Id of 8th subnet :-  192.168.10.   1000 0000  (first 4 digit for subnet )

Broad cast Id of 8th Subnet : 192.168.10.   1000 1111

Last useful ip address for E0 router Interface will be : 192.168.10.   1000 1110 ---->192.126.10.142

Option A is correct.

Comments

@Nisha Bharti

Yes but this is the broadcast address of 7th subnet

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then what is the 1^st ip for 7^th subnet?

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7th subnet network id will be:- 192.168.10.0111 0000  non assignable ip address

7th subnet broadcast id will be:- 192.168.10.0111 1111  non assignable ip address

from 192.168.10.0111 0001 to 192.168.10.0111 1110    we have (2^4) -2 ip addresses are assignable.