CISCO CCNA Exam – Q130

Refer to the exhibit.
CISCO CCNA Exam – Q130

Which address range efficiently summarizes the routing table of the addresses for router Main?

A. 172.16.0.0./21
B. 172.16.0.0./20
C. 172.16.0.0./16
D. 172.16.0.0/18

Correct Answer: B

Explanation:
The 172.16.0.0./20 network is the best option as it includes all networks from 172.16.0.0 – 172.16.16.0 and does it more efficiently than the /16 and /18 subnets. The /21 subnet will not include all the other subnets in this one single summarized address.