military acronym: Nonsecure Internet Protocol Routed NETwork

The NIPRNET is the IP backbone used by the Department of Defense. It is managed by DISA, who provides points of presence on military bases and DoD facilities worldwide. The NIPRNET is sometimes called MILNET, especially by civilians.

The NIPRNET is for unclassified data processing only; classified work must be done on SIPRNET or higher-level networks.

The standard NIPRNET IP-space is for a facility to receive a Class B address, of which the a.b.120.* subnet is used for the connection between the DISA router (a.b.120.1) and the base router (usually a.b.120.10). Various systems that are usually located on the perimeter network will receive the same 4th octet worldwide.