DNS subdomains 'randomly' not accessible

I have several customers who cannot access any subdomains, but the main domains load properly. However, this is not a universal problem. It seems to affect mostly RoadRunner customers, but there are some non-RR people who are also affected. Any suggestions at things I can look at?

Edit: The people affected by this can get to subdomains for some domains on the server, but have difficulty with certain domains.

We’ve had this problem too. I can say that at the very least they are aware of the problem and investigating.

CMI, you just jogged my memory to the possible solution. Martin, are you using Sago’s DNS servers by chance?

Chris

No, I’m not. However, I seem to have more users with problems using Roadrunner than anything else, maybe half of them.

Found the problem. It was a poor configuration on my part. Lack of entries for the ns1 and ns2 nameservers for the domain hosting the DNS, and a flawed SOA implementation.

Most DNS lookups worked fine because the servers were configured with lax settings. Those that required better verification failed lookups on all subdomains, and some base domains.