SQL Server Performance

SQL Cluster and DNS Server

Discussion in 'SQL Server Clustering' started by stevem123, Sep 29, 2004.

  1. stevem123 New Member

    I have a active/active SQL cluster with each server also running as a domain controller and DNS server (not the best situation, but due to limited servers in the location where these machines sit there wasn't another option but to do this).

    I am now entercountering some DNS issues. DNS records for these SQL servers, the cluster, etc.do not seem to populate from Active Directory where I can see they exist into the DNS Service itself (this is a Active-directory integrated DNS zone). I'll be using the NETDIAG tool from Microsoft to try to resolve this issue. That really isn't really an issue for this forum, but it brings up a question about DNS and clusters in general.

    I have added hosts files that contains all the host records for the cluster,etc. to all my other Windows boxes since they cannot rely on the internal DNS servers that are not running properly. At this time the cluster and SQL and access are working fine even though the internal DNS servers do not.

    My concern is that I may have to recreate a new DNS zone or reinstall DNS if I cannot recover the existing zone that does not populate properly. I am waiting to do this on off-peak hours. This would mean there would be a period of time where there is no DNS server (which is technically what I have now anyways, but I wonder if the cluster is using any cached info).

    What problems will this cause if any on the cluster having no DNS server for a short period while it is rebuilt?

    Does the cluster service or SQL instances use DNS and require it to run?

    IN terms of TCPIP settings, each clustered server points to themselves for primary and the other clustered server for secondary DNS. I could add the same hosts file to these machines as well.

    Sorry if it is a bit off topic.



  2. Twan New Member

    Hi ya,

    Removing DNS from domain controllers... not something I'd want to try... AD relies heavily on DNS for resolution, not just of server names, but also service locator records (i.e. finding the DCs to be able to authenticate against.)

    The cluster itself should be ok, although since you are working on the core of your domain, ensuring you have good backups and having a window large enough to rebuild the entire cluster (and therefore domain) would be prudent...

    I guess your organisation is not very large? Having the dcs on the sql cluster is a bad idea for lots of reasons. I'd run the dcs on pcs before I run them on a sql cluster...

    Cheers
    Twan
  3. stevem123 New Member

    Thanks Twan.

    I'm planning on trying to resolve this weekend when usage is lower.

    I am hoping the worst case would be that I have setup DNS to run on another machine and point the cluster boxes there or manually enter the 8-10 host entries that the DNS service cant seem to find in the active directory or just add a hosts file that I assume that cluster will use.

    Putting the DC's on the cluster isn't the best idea, but the only other systems around on its isolated network at our colocation provider are web servers and the domain itself only exists for the purpose of the cluster (and only the cluster boxes point to eachother for DNS). It doesnt seem to put much load on the server itself.

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