CREST Practitioner Security Analyst (CPSA) Practice

What does the term CIDR stand for?

1. Classless Internet Domain Routing

2. Classless Inter-Domain Routing

3. Classful Internet Domain Routing

4. Class Domain Routing

The correct answer is: Classless Inter-Domain Routing

The term CIDR stands for "Classless Inter-Domain Routing." This concept is essential for understanding how IP addresses are allocated and routed on the internet. CIDR was introduced to improve the efficiency of IP address usage and to expand the range of address allocation beyond the traditional classful network structure. In CIDR, IP addresses are represented with a prefix that indicates the network portion and a suffix (often in the form of a slash followed by the number of bits) that specifies the number of bits used for the network mask. This allows for more flexible IP address allocation, which helps in reducing waste of IP space and in managing the growing number of networks. The reason this choice is accurate is because it reflects the modern approach to Internet routing, which does not require class-based division (like Class A, B, and C). Instead, it supports variable-length subnet masking, enabling better aggregation of routes, reducing the size of routing tables, and ultimately leading to more efficient use of IP addresses. Other options do not provide the correct terminology or concepts related to the actual technical framework established by CIDR.