What is the significance of using CIDR in routing?

Using Classless Inter-Domain Routing (CIDR) significantly benefits routing by allowing the aggregation of multiple IP ranges into a single routing entry. This method enhances the efficiency of routing tables, especially in large networks. By summarizing several contiguous IP addresses into a single entry, routers require less memory and processing power to manage routes, leading to faster routing decisions and improved performance.

CIDR works by using prefix notation, which allows for the representation of IP addresses and their associated network prefix in a more flexible way compared to classful addressing. This aggregation reduces the size of routing tables on routers, thereby minimizing the amount of routing information they need to process, which can enhance convergence times and routing efficiency across the internet.

The other options, while related to IP addressing or routing in some way, do not capture the primary significance of CIDR as effectively as the ability to aggregate routes. For instance, while CIDR might influence aspects of IP address assignment and could indirectly impact how reassignment is handled, those are not its primary purposes. Additionally, improving security measures is not a direct function of CIDR; it primarily focuses on routing efficiency rather than security enhancements.