What is the CIDR notation for a Class A address?

CIDR notation, or Classless Inter-Domain Routing notation, is used to specify the number of significant bits in the subnet mask. A Class A address is characterized by its first octet (the first 8 bits) starting with a binary '0'. This means that the range of Class A addresses spans from 0.0.0.0 to 127.255.255.255, which allows for a vast number of hosts per network, making Class A suitable for very large organizations.

In CIDR notation, a Class A address has a default subnet mask of 255.0.0.0, which corresponds to 8 bits (or /8) for the network part of the address. This leaves 24 bits for host addresses, allowing for over 16 million possible hosts within a single Class A network.

Thus, the correct answer correctly states that the CIDR notation for a Class A address is /8, indicating that the first 8 bits are used for the network portion, which is a fundamental aspect of understanding IP addressing and subnetting in network design.