A Node Manager monitors the status of multiple servers. The Node Manager
detects server failures, periodically monitors server health status, and
performs server maintenance. When the Node Manager detects a server
failure, it determines whether or not the server should be restarted.
While periodically monitoring servers, the Node Manager may determine how
often to trigger a health check, how long to wait for a response, and how
to proceed if the server is deemed failed. The Node Manager may be
controlled by an Administrative Server directly or by an external
administrative agent. An administrative agent may control the Node
Manager by interfacing with the Administrative Server. The Node Manager
and AS may authenticate each other and encode their communications to
each other for increased security.