Question : SOA fails for external domains with smtpdiag

We have two sits. Our offices and manufacturing in the middle of nowhere and a co-location that houses our website,database and dns server.

For some reason, previous management set up the linux firewall at the colocation as our dns server. NS1, NS2 are pointed to this server. This server is not part of the domain or connected to our local network in our office.

our mx records point to postini for incoming mail. External mail does not go through postini

When I run smtpdiag i get this error sending to external domains

Checking TCP/UDP SOA serial number using DNS server [69.30.46.55].
Failed: DNS server [69.30.46.55] may be down.
DNS server [69.30.46.55] did not return a valid SOA record.
SOA serial number match: Failed with one or more failures.

internal emails on our domain are fine.
Checking TCP/UDP SOA serial number using DNS server [69.30.46.55].
Failed: DNS server [69.30.46.55] may be down.
DNS server [69.30.46.55] did not return a valid SOA record.
SOA serial number match: Failed with one or more failures.

How can I fix this?

Answer : SOA fails for external domains with smtpdiag

Do you have internal and external dns servers set on this machine? It looks like it works fine when querying your internal nameservers, but fails when looking at the external one. I tried querying the SOA record from 69.30.46.55 and it worked fine. Are you blocking/rejecting dns traffic from certain internal clients or something?