CISSP Practice Exam 2026 – Complete Prep Guide

CIDR stands for Classless Inter-Domain Routing, a method used in networking to allocate IP addresses and manage Internet routing more efficiently. This approach differs from the traditional classful addressing system, which divided IP address space into fixed classes (A, B, and C). CIDR allows for more flexible allocation of IP address ranges without being limited by class boundaries, enabling better usage of the IP address space.

With CIDR, IP addresses can be grouped in a way that aligns more closely with actual usage, helping to reduce the size of routing tables and improve overall network performance. For example, CIDR utilizes notation like "192.168.0.0/24" to specify addresses, where the "/24" indicates the subnet mask. This flexibility in subnetting provides significant advantages in routing and the management of IP addresses across different networks.

The concepts provided in the other options do not align with standard networking terminology or practices associated with CIDR, which is specifically focused on address allocation and routing efficiency. Therefore, the correct understanding of CIDR as Classless Inter-Domain Routing is essential for managing modern network infrastructures effectively.