This update method uses WMI (Windows Management Instrumentation) to communicate with Microsoft DNS servers on Windows 2000 Server and Windows 2003 Server.
Simple Failover performs the following steps to check and update DNS:
 First, based on the monitoring results, it figures out what the DNS records should be for the Server Set domain name:
| - If the Server Set is configured to use DNS round robin (load balancing), then it will configure one A-record for each of the functional servers.
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| - If the Server Set is not configured to use DNS round robin, then it will configure a single A-record for the first functional server.
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| - If none of the servers were functional, then Simple Failover will assume that the problem must be local, and it will configure A-records as if the first/all servers did respond correctly.
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| - If the Server Set Failed Polls Accepted setting is greater than zero, then each server is considered functional, until it has been found non-functional more times than this number.
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 Then it sends a DNS request to the DNS server to check the current DNS A-records for the Server Set domain name.
| If this is already what it should be (1), then the process stops here as there is no need to update anything.
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 Next it sends a DNS request to the DNS server to get the SOA-record for the Server Set domain name.
| This will return the DNS zone name that the domain name belongs to (needed for the update process).
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 And finally it performs the following via WMI:
| a) Delete any existing A- and CNAME-records for the Server Set domain name.
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| b) Add new A-records as per the monitoring results (1).
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While communicating with the DNS server, Simple Failover may encounter communication errors (winsock errors), time outs, or unexpected responses. Such problems will be logged, listed in the problems list, and invoke e-mail and script notifications.
For specific instructions for using this update method, see the Microsoft DNS section.
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Update DNS via WMI
