What does CIDR stand for in networking?

CIDR stands for Classless Inter-Domain Routing. This concept was introduced to improve the allocation of IP addresses and enhance the routing process on the internet. The key aspect of CIDR is that it allows flexible subnetting, meaning that IP addresses can be assigned in a more efficient manner than under the classful addressing system, which divided addresses strictly into classes (A, B, C) without considering the actual needs of the networks.

Under CIDR, IP addresses are assigned based on variable-length subnet masking (VLSM), which allows networks to be of different sizes and leads to reduced waste of IP addresses. This method helps to conserve address space, especially important with the limited availability of IPv4 addresses. CIDR also simplifies the routing table by allowing multiple IP addresses to be aggregated into a single routing entry, thus optimizing network routing and performance.

In summary, Classless Inter-Domain Routing effectively addresses the limitations of the previous classful system, making it more suitable for the dynamic and diverse requirements of contemporary networks.