DNS CLustering
 

Do any of you know if its possible to cluster Microsoft DNS servers, or do you just go down the primary and secondary server route?

I don't think you need to cluster a DNS server. Why would your DNS server be under such a heavy work load? Just sounds odd to me to put that much money into a simple DNS server.

Have you checked the hardware to make sure that your hard drive is not having a failure. I read that sometimes the workload and over used resources could mean a sign of a bad drive.

You don't cluster DNS servers in a traditional active/passive sense using MSCS. You replicate the DNS Zone files. Check out this article explaining some replication methods: DNS zone replication in Active Directory: Domain Name System(DNS)