AWS Certified Advanced Networking Specialty Practice Exam 2026 - Free Advanced Networking Practice Questions and Study Guide

To accommodate over 250 addresses in a VPC subnet, it's essential to choose a CIDR block that allows for sufficient IP addresses.

When determining the number of usable addresses in a subnet, the formula to calculate usable IP addresses is 2^(32 - subnet mask bits) - 2. The "-2" accounts for the network and broadcast addresses, which cannot be assigned to hosts.

For the CIDR block 192.168.1.0/23:

- The subnet mask is 23 bits, meaning there are 32 - 23 = 9 bits left for host addresses.

- Using the formula, this gives us 2^9 - 2 = 512 - 2 = 510 usable addresses.

This means that a /23 subnet can accommodate significantly more than 250 IP addresses, making it suitable for the requirement outlined in the question.

Other CIDR blocks provided do not meet the requirement:

- A /24 provides 256 total addresses, which after accounting for the network and broadcast addresses leaves only 254 usable addresses—less than needed.

- A /25 provides just 126 usable addresses, insufficient for the requirement.

- A /22 yields 1022 usable addresses, which exceeds the need but also