What is the default subnet mask for a Class A IP Address?

The default subnet mask for a Class A IP address is indeed 255.0.0.0. Class A addresses are defined by their range, specifically from 1.0.0.0 to 126.255.255.255, which allows for a vast number of hosts on a single network. The default subnet mask of 255.0.0.0 indicates that the first octet (the first 8 bits) is used to identify the network, while the remaining three octets (the last 24 bits) are available for host addresses. This allows for over 16 million possible host addresses within a single Class A network.

In contrast, the other options represent default subnet masks for different classes of IP addresses. The 255.255.255.0 mask is associated with Class C addresses, which support smaller networks. The 255.255.0.0 mask is linked to Class B addresses, which are suited for medium-sized networks. The 255.255.255.255 mask is a special broadcasting address used for specific network communication, not a default subnet mask for any class of IP address. Understanding these distinctions is crucial for grasping IP addressing and subnetting concepts.