Is 172.16.0.1 a valid host address in a Class B network 172.16.0.0/16?

• A. Yes
• B. No
• C. Not enough information
• D. It depends on subnetting

Answer: (A)

In a 172.16.0.0/16 network, the first two octets identify the network and the last two are the host part. With a /16 mask (255.255.0.0), the network address is where the host portion is all zeros (172.16.0.0) and the broadcast for that network is where the host portion is all ones (172.16.255.255). Any address within that network that isn’t the network or broadcast is a valid host address. 172.16.0.1 has a host portion of 0.1, which is neither all zeros nor all ones, so it’s a usable host address in this /16 network. This address also falls inside the private address space commonly used for internal networks.