Bind9 Server clients getting random ServFail Error
 

Hi. I have an Ubuntu Server set up as a Bind9 server for internal DNS. It uses OpenDNS for forwarding of outside domains. This generally works quite well. I have Windows, Linux, and Mac clients that use this DNS Server, generally without issue. On occasion, however, I will get a servfail error when trying to query my DNS Server. Sometimes restarting will fix this, and sometimes clearing the DNS cache will, but not always. Even if these fixes did always work, I'd still be frustrated - I can't figure out why this happens in the first place! A few more details:

• This will only happen on one client at a time - there is no mass failure
• The issue will eventually just resolve itself
• Even while this is happening, my DNS Server can ping the client machine, and the client machine can ping the DNS Server.
• If I try the same DNS queries that are failing on one client on another client (or on the server itself), they work fine.

I am pulling my hair out! Any help is greatly appreciated. I've still got lots and lots to learn about DNS.

Any additional information that you need to answer my question? I could really use some help!