I recently just setup a SQL Server 2012 Failover Cluster Instance on Windows Server 2008 SP2. When I do a failover test, it took about 3 minutes plus to completely failover to second node. Meanwhile, failback took the same time as well. I used to setup SQL Cluster in Windows Server 2012, 2016 and 2019, all just took about 10 seconds to complete the failover/failback. Don't understand why is this cluster on Windows Server 2008 took that long?
From cluster event I can only see a warning about the DNS server failure & that operation returned timeout period expired. The DNS server status of the cluster resource is OK and I can see it successfully registered the host record in DNS server.
Any idea? Is it due to OS version or above error logs causing this issue?