What is the appropriate netmask for a Class A address?

A Class A address is characterized by its first octet starting with a binary '0', which means that it ranges from 1 to 126 in decimal values. The default subnet mask for Class A networks is /8, which indicates that the first 8 bits (or the first octet) are used for the network part of the address, while the remaining 24 bits are reserved for host addresses within that network.

This structure allows for a vast number of hosts (over 16 million) to be accommodated within a single Class A network. The flexibility provided by using /8 for the netmask enables organizations with Class A addresses to allocate significant address space, making it ideal for large networks.

Other options reflect default subnet masks for different classes of addresses or specific use cases. For example, /16 corresponds to Class B addresses, /24 is typical for Class C, and /32 represents a single host address. Therefore, /8 is the appropriate netmask for a Class A address as it aligns with the fundamental design of Class A networks, which are structured to support a broader range of hosts.