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Networking · Q9

Subnetting

Programming · Networking · question 9

Q9

What is the subnetwork number of a host with an IP address of 172.16.66.0/21?

A.
172.16.36.0
B.
172.16.48.0
C.
172.16.64.0
Answer
D.
172.16.0.0

Answer: Option C

Solution

Answer: Option C
Solution:
A /21 is 255.255.248.0, which means we have a block size of 8 in the third octet, so we just count by 8 until we reach 66. The subnet in this question is 64.0. The next subnet is 72.0, so the broadcast address of the 64 subnet is 71.255.