An APPN network node provides directory services to its locally resident LUs and to the LUs in its client end nodes. It also assists other network nodes in the network in their search for resources. When network nodes learn the location of resources by searching, they cache the location of these resources in the local directory database.

The network node and the collection of resources it serves are called a network node domain. For an LU located in a network node, the local directory maps an LU name to the CP name of the network node where that LU is located. For an LU located in an end node, the directory includes the CP name of the owning end node and the end node's network node server.

Because APPN end nodes do not maintain a directory database, an end node that does not currently have CP-CP sessions with a network node server cannot establish sessions with resources located on other nodes unless these resources are predefined in a manner similar to low-entry networking partner LU definitions.

A low-entry networking node or APPN end node maintains a local directory containing entries for locally resident LUs. An APPN end node that does not currently have CP-CP sessions with a network node server also maintains entries for those resources residing in an adjacent node connected as a peer, such as another end node.

Entries in a low-entry networking node are defined manually. Because it does not support CP-CP sessions (it cannot have a network node server), a low-entry networking node sends an LU-LU session activation (BIND) request over the link associated with the predefined session partner. If the destination LU is located in a node that is not adjacent to the low-entry networking node, it must be connected to a network node. This network node can locate the resource and select the appropriate route.

An APPN end node has an alternative to the low-entry networking's complete directory of all LUs with which it initiates sessions: it can initiate a locate search into the APPN network to find a desired LU by invoking the services of its network node server. Because the network node server identifies the route to be used for the requested session in its search reply, the resulting LU-LU session is not required to traverse the network node server.