2.9.4 Unavailability of Networking

A functional networking system is vital to the ability of clients to communicate with the directory server. If the networking system becomes unavailable, clients cannot send any new requests to the directory server, and they cannot receive any responses to outstanding requests. A functional networking system is also vital to the ability of directory servers to replicate directory data among themselves. This situation could cause a temporary loss of system coherency if segments of the network that are part of the same domain cannot communicate with each other but clients and domain controllers within the segments can still communicate.

Networking could become unavailable due to a hardware failure, such as the failure of a network switch or router, or a software problem, such as misconfiguration of a routing table.

When the directory server is in this state, it cannot respond to any requests that clients attempt to send to it, and directory servers cannot respond to replication requests. As such, it is beneficial for clients and directory servers to enforce a time-out on any requests that they send so that they do not stop responding indefinitely while they wait for a response.

After the network becomes available again and communications are restored between the client(s) and the directory server and among directory servers, individual directory servers resume processing requests in accord with the behavior described in the Technical Documents. The loss of networking does not in itself cause any change in the state of the abstract data of the system's protocols.