Inside a device, every address mask is stored as a 32-bit number. When we submit a prefix and an address mask they use a changed form of dotted decimal addressing known CIDR addressing, which is called as CIDR Presentation.

As an example how CIDR includes flexibility, consider a single class B prefix (e.g. 128.201.0.0) i.e. 216 host addresses 16-bit CIDR mask shows as: 128.211.0.0/16

That is, by creating CIDR mask corresponds same to the old Classful interpretation. It will be ok if 216 receivers are attached. If it does have two clients with only twelve devices each, the ISP can need CIDR to partition the address into three parts.

• Two of them each large enough for one of two clients.
• Remainder available for future clients.

For example one client can be given 128.211.0.16/28 and the other client can be given 128.211.0.32/28. Both client have similar mask size, the prefix differs i.e. each and every client has a unique prefix.

CIDR HOST ADDRESSES:

The example below in the diagram denotes the CIDR host addresses: