GATE | GATE CS Mock 2018 | Set 2 | Question 55
Consider the given network implementation scenario. For the given classful NID 184.108.40.206/24, the requirement is to create 13 subnets. With given details, find the range of first and last valid IP in 15th subnet.
(A) 220.127.116.11 to 18.104.22.168
(B) 22.214.171.124 to 126.96.36.199
(C) 188.8.131.52 to 184.108.40.206
(D) Not of these
Explanation: Default mask : 255.255.255.0
We are supposed to create 13 subnets, which is not possible becuase subnets can be created only in powers of 2. Subnet leads to wastage of IP, that’s the reason we moved to VLSM.
No of subnets = 2^4 = 16 subnets
means, 4 host bits are borrowed. Which makes subnet mask
11111111.11111111.11111111.11110000 199 .10 .20 .240
Block size = 256-240 = 16
Valid IP per subnet ID = 2^n – 2 , where n = no of host bits left 2^4-2 = 14
First Subnet :
1st IP : 220.127.116.11
1st valid IP : 18.104.22.168
Last valid IP : 22.214.171.124
Last IP : 126.96.36.199
In 2nd Subnet, 1st IP : 188.8.131.52 and last IP : 184.108.40.206
In 3rd Subnet, 1st IP : 220.127.116.11 and last IP : 18.104.22.168
In 15th subnet, 1st IP : 22.214.171.124 , 1st Valid IP : 126.96.36.199
Last IP: 188.8.131.52 , Last Valid IP: 184.108.40.206
Answer : Option (b)
Quiz of this Question
Attention reader! Don’t stop learning now. Practice GATE exam well before the actual exam with the subject-wise and overall quizzes available in GATE Test Series Course.
Learn all GATE CS concepts with Free Live Classes on our youtube channel.