What is the primary advantage of using CIDR (Classless Inter-Domain Routing) in IP addressing?

CIDR allows IP addresses to be allocated based on the actual need rather than adhering to rigid class-based divisions (Class A, B, C). This approach uses variable-length subnet masks (VLSM), which optimize IP address utilization and reduce waste. For example, a network requiring 50 addresses can be assigned a smaller block (e.g., /26) instead of wasting a full Class C range (256 addresses). CIDR also simplifies routing by aggregating multiple networks into a single routing entry, known as route aggregation or supernetting. This reduces the size of routing tables, enhancing scalability and efficiency in large-scale networks. ________________________________________ Why Other Options Are Incorrect? 1. Simplifies routing tables by using fixed-length subnet masks: Incorrect because CIDR uses variable-length subnet masks, not fixed-length. 2. Increases the address space in IPv4 networks: Incorrect because CIDR optimizes usage but does not expand the IPv4 address space. 3. Eliminates the need for default gateways: Incorrect as default gateways remain crucial for routing traffic outside local subnets. 4. Supports only IPv6: Incorrect as CIDR applies to both IPv4 and IPv6.