- Abbreviation of host identification. Within an IP address, the bits which identify a specific host computer. For instance, if in the IP address 126.96.36.199, 151.201 identify the network, then 4.111 are the host ID. The network ID can encompass the first, first and second, or first, second, and third sets of numbers separated by the periods. The rest correspond to the host ID. Also spelled hostID.