What advantage does CIDR notation provide?

CIDR notation, or Classless Inter-Domain Routing, provides a significant advantage in making IP addressing more flexible. By allowing variable-length subnet masking rather than fixed-length classes (as used in the older classful addressing system), CIDR enables more efficient allocation of IP addresses. This flexibility allows network administrators to allocate according to the actual number of hosts needed instead of being constrained to predefined class sizes. For example, instead of being required to use a full class A or class B address, a network can be broken down into smaller, more appropriate sizes that match the specific requirements. This adaptability is particularly beneficial in managing IP addresses in a dynamic and growing internet landscape, enhancing overall network design and planning.

Other choices may touch on related topics, but they do not capture the core advantage of CIDR notation in the way that flexibility does. For instance, while CIDR can contribute to simpler routing by reducing the size of routing tables, that aspect is more of a byproduct rather than the primary advantage.