CIDR Block

CIDR stands for Classless Inter-Domain Routing, which is a method of allocating IP addresses and routing Internet Protocol (IP) packets. A CIDR block is a range of IP addresses that can be assigned to devices on a network.

In CIDR notation, a CIDR block is represented by an IP address followed by a forward slash (/) and a number that indicates the number of significant bits in the network address. For example, a CIDR block of 10.0.0.0/24 would indicate that the network address is 10.0.0.0 and that the first 24 bits of the IP address are used for the network portion of the address, leaving the last 8 bits for device addresses.

CIDR blocks are used to create subnets within a network, which can be used to partition a larger network into smaller, more manageable segments. By assigning CIDR blocks to subnets, network administrators can control IP address allocation and routing within the network.

CIDR blocks are also used to allocate IP addresses to virtual private cloud (VPC) networks in public cloud environments. In this case, the CIDR block is used to define the IP address range for the VPC and the subnets within it.