Will CIDR completely eliminate IP address crunch problem?

No. Even using CIDR, all the available IP addresses will get used at some point in time. The final solution to this problem is to use the next version of IP (IPv6).

How CIDR reduces the number of entries in a routing table?

Using classful IP addressing, a separate entry is needed in the routing table of a router for each network. This results in a routing table with a large number of entries due to the existence of a large number of networks. As each router has its own limitation, this large routing table will lead to reduced performance and eventual breakdown of the router. If CIDR addressing is used, a single entry can be used to represent a group of networks. This will reduce the number of entries in the router. This is known as route aggregation. The routes for the individual networks will be present in another router down the path. Each entry in the router will have a network prefix associated with it. The network prefix is used to identify the correct network from the given IP address.

How CIDR can be used to effectively manage the IP address space?

Using CIDR IP addressing, any number of contiguous bits can be assigned to identify networks, depending on the number of hosts it needs to support. This will greatly reduce the number of wasted IP addresses. For example, let us say a network has 900 hosts. If classful IP addressing is used, this network needs 4 class C IP addresses or one class B IP address. If a class B IP address is used, as the maximum number of hosts in a class B network is 65534, a very large number (65534 - 900) of host IP addresses will be wasted. As the number of class C IP networks is limited (2097152), it is not preferable to assign 4 class C IP addresses to this network. On the other hand, if CIDR is used, then this network can be assigned an IP address with a network prefix of 22 (i.e. /22). This means, 10 bits are available for hosts, resulting in 1024 available host IP addresses, satisfying the exact requirements of the network. So CIDR the IP address space can be effectively used.

What are the advantages of CIDR?

The advantages of CIDR over the classful IP addressing are:

1. CIDR can be used to effectively manage the available IP address space.

2. CIDR can reduce the number of routing table entries.