I have a W2K DNS server on the internet. I can ping host.mydomain.com, www.mydomain.com, etc. That all seems to respond just fine. I entered an MX record and called it mail.mydomain.com and put the IP address of a sendmail Linux fedora box I am using to test some work. All the FQDNs I listed above go to this same Linux box.
I can ping the other host names, I can ping by IP address, I CAN NOT PING BY NAME TO "mail.mydomain.com".
I made sure it WAS an "MX" record.
I tried little things like making sure the firewall was temporarily taken down to test between these boxes if the ping went through. But whenever I try to ping mail.mydomain.com I get an Unknown host error. No error when I type ping host.mydomain.com, www.mydomain.com, etc. I entered another A record, and I can ping that.
I have cleared the cache on my internal DNS, and run ipconfig /flushdns on my client windows machines.
I even get Unknown host error when I trying to ping mail.mydomain.com FROM THE DNS SERVER!
Yet I see the darn recording in the domain folder for the domain in question, pointing to the IP address (also tried pointing the MX record to another host name that leads to the same Linux box)
I have run nslookup on the windows and Linux machines and tried to get it to tell me the IP of mail.mydomain.com and get *** Can't find mail.mydomain.com: No answer or NOTHING on the windows machine.
I either don't know something, or I forgot something I knew once.