Consider an IP address 160.80.40.20 and given Subnet mask is 255.255.240.0. Which of the following option is correct for the Subnet Id and last allowed Host address?
(A) 160.80.40.0 and 160.80.32.254
(B) 160.80.32.0 and 160.80.32.255
(C) 160.80.40.0 and 160.80.47.255
(D) 160.80.32.0 and 160.80.47.254


Answer: (D)

Explanation: Given IP – 160.80.40.20 and subnet mask 255.255.240.0. So, convert the given IP and Subnet Mask from decimal to binary and take bitwise and between them,

     IP     - 10100000.01010000.00101000.00010100
Subnet Mask - 11111111.11111111.11110000.00000000
-----------------------------------------------------
Subnet Id   - 10100000.01010000.00101000.00000000
----------------------------------------------------- 

Which is equivalent to 160.80.32.0.
Now, the last subnet on this subnet will be:

Last Host Id - 10100000.01010000.00101111.11111110 

Which is equivalent to 160.80.47.254

Hence, option (D) is correct.

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  • Last Updated : 31 Oct, 2018

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