Question

Which one of the following CIDR prefixes exactly represents the range of IP addresses \(10.12.2.0\) to \(10.12.3.255\)?

• A. \(10.12.2.0/23\)
• B. \(10.12.2.0/24\)
• C. \(10.12.0.0/22\)
• D. \(10.12.2.0/22\)

Hint:

To find the correct CIDR prefix, calculate the subnet mask and verify the range of IPs it covers.

Answer 1

The Correct Option is A

The given range is \(10.12.2.0\) to \(10.12.3.255\).
The CIDR notation \(10.12.2.0/23\) has a subnet mask of \(255.255.254.0\), which covers the following range of IPs: \[ 10.12.2.0 \, \text{(start)} \, \text{to} \, 10.12.3.255 \, \text{(end)}. \] Other options do not correctly represent this range:
(B) \(10.12.2.0/24\): Only covers \(10.12.2.0\) to \(10.12.2.255\).
(C) \(10.12.0.0/22\): Covers a larger range from \(10.12.0.0\) to \(10.12.3.255\).
(D) \(10.12.2.0/22\): Invalid as it overlaps incorrectly with the range \(10.12.4.x\). Final Answer: \[ \boxed{\text{(A)}} \]