Defense Data Network

worldwide communications network for the U.S. Department of Defense and U.S. Military (Telecommunications)

The Defense Data Network (DDN) was a separate instantiation of the ARPANET used by the United States Department of Defense from 1983-1995 for its Internet services.The DDN began as the MILNET, a network formed in 1983 when military sites split off the public ARPANET. As a large-scale, private internet, the DDN provided Internet Protocol connectivity across the United States and to US military bases abroad. Throughout the 1980s it expanded as a set of four parallel military networks, each at a different security level. These networks transitioned to become the NIPRNET, SIPRNET, and JWICS networks in the 1990s.
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A component of the Defense Communications System used for switching Department of Defense automated data processing systems. [JP1-A]

(DDN) A global communications network serving the US Department of Defense. Composed of MILNET, other portions of the Internet, and classified networks which are not part of the Internet. The DDN is used to connect military installations and is managed by the Defense Information Systems Agency.
(1994-12-01)