An administrative domain is a service provider holding a security repository permitting to easily authenticate and authorize clients with credentials.
This concept is captured by the 'AdminDomain' class of the GLUE information model.
[1] An administrative domain is mainly used in intranet environments.
It may be implemented as a collection of hosts and routers, and the interconnecting network(s), managed by a single administrative authority.
Therefore, administrative domains wishing ad hoc interoperation or full interoperability have to build a federation.