[8.930] Internal DNS resolution

I have two internal AD 2003 DNS servers identified by host records on my internal network. There are two DNS request routes, one for the domain, the other for reverse lookups. Both DNS servers can be pinged (and for the rest of the internal network they correctly resolve internal addresses). The Astaro DNS proxy log indicates it is trying to connect but fails:

2012:04:13-17:09:01 astaro2 named[4345]: host unreachable resolving '245.200.168.192.in-addr.arpa/PTR/IN': 192.168.200.37#53
2012:04:13-17:09:01 astaro2 named[4345]: host unreachable resolving '245.200.168.192.in-addr.arpa/PTR/IN': 192.168.200.33#53
2012:04:13-17:09:01 astaro2 named[4345]: host unreachable resolving '245.200.168.192.in-addr.arpa/PTR/IN': 192.168.200.37#53
2012:04:13-17:09:01 astaro2 named[4345]: host unreachable resolving '245.200.168.192.in-addr.arpa/PTR/IN': 192.168.200.33#53
2012:04:13-17:10:01 astaro2 named[4345]: host unreachable resolving 'acc.nsasia.co.th/A/IN': 192.168.200.37#53
2012:04:13-17:10:01 astaro2 named[4345]: host unreachable resolving 'acc.nsasia.co.th/A/IN': 192.168.200.33#53
2012:04:13-17:10:01 astaro2 named[4345]: host unreachable resolving 'crm.nsasia.co.th/A/IN': 192.168.200.37#53
2012:04:13-17:10:01 astaro2 named[4345]: host unreachable resolving 'crm.nsasia.co.th/A/IN': 192.168.200.33#53
2012:04:13-17:11:02 astaro2 named[4345]: host unreachable resolving 'acc.nsasia.co.th/A/IN': 192.168.200.37#53
2012:04:13-17:11:02 astaro2 named[4345]: host unreachable resolving 'acc.nsasia.co.th/A/IN': 192.168.200.33#53
2012:04:13-17:11:02 astaro2 named[4345]: host unreachable resolving 'crm.nsasia.co.th/A/IN': 192.168.200.37#53
2012:04:13-17:11:02 astaro2 named[4345]: host unreachable resolving 'crm.nsasia.co.th/A/IN': 192.168.200.33#53

Public lookups function correctly.

Is anyone else having a problem with this? How can I better trouble shoot this?