To fully identify a host you need which?

• A. MAC address and IP
• B. IP address and DNS
• C. Hostname only
• D. IP address and netmask

Answer: (D)

In TCP/IP addressing, you identify a host by both its address and the network context it sits in. The IP address tells you the specific device on the network, but the netmask defines which portion of that address is the network and which part identifies the host within that network. Together, they let you determine the network address, the range of usable host addresses, and whether a destination is on the same local subnet or requires routing to another network. The other options don’t provide the full scope: a MAC address with an IP shows hardware mapping but not the network boundary; DNS just maps names to IPs and doesn’t define subnet scope; a hostname alone doesn’t uniquely identify the device within a network or across networks. Therefore, the combination of IP address and netmask is the correct pairing.