What does the host address portion of an IP address do?

• A. Identifies the network
• B. Identifies the gateway
• C. Uniquely identifies each machine on a network
• D. Identifies the subnet

Answer: (C)

The host address portion identifies the specific device on the local network. In IPv4, an address is split into a network part and a host part (as defined by the subnet mask). The network part tells routers which network the device belongs to, while the host part differentiates each device within that network. This separation ensures every device on the same network has a unique host identifier, so packets can be delivered to the correct machine. For example, on a 192.168.1.0/24 network, 192.168.1.42 uses 192.168.1 as the network portion and 42 as the host portion, uniquely identifying that single device on the network. The gateway’s address is simply the router’s address on that network, used to reach other networks, not a function of the host portion itself. The subnet is determined by the network portion and the mask, not by the host portion.