Description: CIDR (Classless Inter-Domain Routing) for VPC (Virtual Private Cloud) is a notation that defines the range of IP addresses assigned to a VPC in cloud networking environments. This notation allows for a more flexible and efficient specification of IP address blocks than the traditional class system. Instead of being limited to classes A, B, or C, CIDR allows for the allocation of IP addresses in variable-sized blocks, optimizing address space usage and facilitating network management. CIDR notation is expressed as a range of addresses followed by a slash and a number, indicating the prefix length. For example, an address block might be represented as 192.168.0.0/24, where the ‘/24’ indicates that the first 24 bits are the network part and the remaining 8 bits are for hosts. This flexibility is crucial in cloud environments, where network needs can vary significantly across different applications and services. Additionally, using CIDR in VPC allows users to create subnets, manage routing, and apply security policies more granularly, resulting in a more efficient and scalable network architecture.
History: CIDR was introduced in 1993 as a solution to the scarcity of IP addresses and the growing complexity of routing on the Internet. Before CIDR, the classful addressing system (A, B, and C) was inefficient, as many address blocks were underutilized. The implementation of CIDR allowed for more efficient address allocation and a reduction in the size of routing tables, facilitating the expansion of the Internet.
Uses: CIDR is primarily used for the efficient allocation of IP addresses in networks, allowing network administrators to define variable-sized address blocks. It is essential for creating VPCs and subnets, as well as for managing routing and security policies. It is also used in VPN configurations and in implementing high-availability solutions.
Examples: A practical example of CIDR would be creating a VPC with an address block of 10.0.0.0/16, allowing for up to 65,536 IP addresses. Within this VPC, subnets could be created such as 10.0.1.0/24 for a public subnet and 10.0.2.0/24 for a private subnet, facilitating the organization and management of network resources.
