Release 10.1A: OpenEdge Application Server:
Administration

> ## Fault-tolerant NameServers

> You can configure NameServer such that a group of NameServers work together to resolve a client connection request. Having a group of NameServers working together to resolve the request provides fault-tolerant access to the NameServer function.

> OpenEdge provides two mechanisms that you can use to implement fault-tolerant NameServers, and you can use them independently or together:

> - NameServer replication — Where you configure multiple NameServer instances within a single subnet on different machines to listen on the same User Datagram Protocol (UDP) port. Clients send connection requests and AppServers send registration requests to all NameServer instances using UDP broadcasting. Broadcasting allows a set of replicated NameServers to be set up as one controlling NameServer for each AppServer instance.

> - NameServer neighbors — Where you configure multiple NameServers on machines located in one or more subnets so that an initial NameServer instance receives the client connection request. If this initial NameServer cannot resolve the request, it passes the request on to a specified list of NameServer neighbors. These NameServer neighbors then attempt to resolve the connection request. Each NameServer neighbor represents the controlling NameServer for a separate AppServer instance.

> For more information on setting up fault-tolerant NameServers, see OpenEdge Getting Started: Installation and Configuration .

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