What is the subnet mask for Class A addresses?

The subnet mask for Class A addresses is 255.0.0.0. This subnet mask is used to identify the network and host portions of an IP address in the Class A range, which includes addresses from 1.0.0.0 to 126.255.255.255.

In Class A, the first octet is used to represent the network part, allowing for a large number of host addresses, which is reflected in the subnet mask where the first 8 bits (the first octet) are set to 255 (or all bits set to 1 in binary, indicating the network part), and the remaining 24 bits are available for host addresses (set to 0). Thus, the subnet mask effectively determines the size of the network and how many devices can be addressed within that network.

This is crucial for network design, where understanding the boundaries between networks and the number of devices that can be accommodated in those networks is essential for efficient IP management and communication.