A customer of us has a issue with an e-mail server. It's trying to do a DNS reverse lookup of its private IP address, but It doesn't find it in the DNS server:
192.168.100.9 (Reverse lookup) - error could not reverse lookup 192.168.100.9 in DNS: No PTR record found for domain...
A PIX firewall has a static NAT rule for this server. I've tried to perform DNS doctoring but it doesn't work. I've read that “Therefore, reverse lookups, which request the PTR record, are not affected by DNS rewrite.”
Regards and thanks in advance.
When the server tries a reverse DNS lookup for its private IP, the DNS has no information about it (since as you mentioned it only knows about the public IP).
DNS Doctoring is for instance, if you want your inside LAN to access the SMTP server on the DMZ with it's public IP.
So, the DNS resolves the public IP for the SMTP server, but the PIX translates the DNS reply to the real IP of the SMTP server, so the request is forwarded to the DMZ interface and not to the outside.
Why is the SMTP server attempting a reverse DNS lookup for its private IP?
What would you like to do, so we can help you out?