How many addresses are in a /32 subnet, and what is it typically used for?

• A. 4 addresses; used for a small network
• B. 1 address; used for a single host route or loopback
• C. 2 addresses; used for point-to-point
• D. 8 addresses; used for broadcast domains

Answer: (B)

In IPv4, a /32 subnet means the subnet mask is 255.255.255.255, so all 32 bits are used for the network portion and there are no bits left for hosts. That makes the subnet contain exactly one IP address. Because there’s no room for other hosts, this single address is used to identify a specific host in routing (a host route) or to designate a loopback interface on a device, which is useful for testing or for giving the device a stable, internal address. Since there’s only one address, there isn’t a separate network or broadcast address within this subnet.