CompTIA Network+ (N10-007) — Question 174

A network administrator has been given a network of 172.16.85.0/21 and wants to know the usable range of IP addresses on that subnet. Which of the following indicates the correct IP address range?

Answer options

• A. 172.16.80.0-172.16.85.254
• B. 172.16.80.0-172.16.88.255
• C. 172.16.80.1-172.16.87.254
• D. 172.16.80.1-172.16.85.255

Correct answer: C

Explanation

The correct answer is C because the /21 subnet allows for a range from 172.16.80.0 to 172.16.87.255, and the usable IP addresses exclude the network address and broadcast address, leading to a usable range of 172.16.80.1 to 172.16.87.254. Options A, B, and D either include invalid addresses or do not match the correct usable range.