Neverfail for Exchange is not supported with WINS registration using management IP addresses in a WAN environment



WINS is an older Microsoft legacy technology for registering and querying dynamic NetBIOS names to IP address mapping in a routed network environment, which is not normally implemented in new network implementations.

Neverfail Heartbeat is designed to integrate with DNS technology where the DNS is itself integrated with the Active Directory. For more information, please refer to KB 238 .

If Neverfail Heartbeat is implemented in a WAN environment where management (or ‘backdoor’) IP addresses are set, Neverfail recommends that WINS is not used for name resolution

More Information

Installing Neverfail Heartbeat into a WINS environment can result in undesired behavior when a Switchover or Failover occurs, if management addresses are used on the pair.

When Neverfail Heartbeat is installed, the Primary server is in the active role. The first IP address from the public NIC of the active server will be registered with the WINS server. This could be the management address of the active server rather than the public address. As a result, clients could resolve the management address of the Primary server via a NetBIOS resolution, rather than the public address. Under normal operating conditions, this isn’t an issue. The issue will occur when Neverfail Heartbeat initiates a Switchover or a Failover to the Secondary server. When the Secondary server switches to the active role, clients are still resolving the management address of the Primary server. The Primary server is now passive, and therefore does not have the protected application running and is not providing a service to the client. The clients at this stage will not be able to connect to the protected application until the Secondary server registers its own public or management address with the WINS server. This could take up to 30 minutes.

The best practice would be not to use management IP addresses and, if possible, to prevent servers hosting Neverfail Heartbeat from using WINS registration.


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