What is Wrong With My Zone? (A Symptom Based FAQ)

Q: Why is my mail server rejecting mail from my domain?
Q: Why do I have a mail loop?
A: Configure your mail server to accept mail for your domain. Mail loops are almost never caused by DNS problems.

Q: People can’t send mail to me. The bounce message says my domain doesn’t exist, or there is no mail server.
A:
1. Check to make sure that your domain is still registered.
2. Make sure you have properly formatted MX records (at least one) Your MX record should look similar to the ones in this example. This Don’t put your mail server’s name in the name field of the record (on the left), a common error.
3. Make sure that the mail server name used in the MX record has an A record; a CNAME record will not suffice. (Example)

Q: I can’t get/send mail because mail servers of ISP’s won’t talk to my mail server.
Q: I’m on a black hole list.
Q: I’m getting a reverse lookup error.
A:
1. Make sure that the name in your MX record matches the name in the PTR record for the IP address.
2. If you are hosting the reverse zone that contains (or should contain) that PTR record, make sure that it's delegated to you. It generally does no good to have a proper reverse zone if nobody can get to it.
3. Make sure that your mail server identifies itself in the SMTP greeting using the
name in the PTR record.
4. If your mail is being black-holed or blocked, make sure that your mail server is
not an open relay. Check the MAPS lists to see if your server is listed on the blackhole list. If it is, go through the procedures outlined on the website to get your mail server removed from the list. 5. Make sure that you aren’t trying to send mail to the world from a dial up account. If your mail server is behind a modem connection dial up, send mail through your ISP.
6. If AOL refuses to talk to your mail server, or simply trashes it, send mail through your ISP/NSP. No user has ever reported having this problem resolved by AOL.

Q: Nobody can get to my site.

A:
1. Make sure your domain is still registered and paid for, preferably to you by you.
2. Make sure there are no mistakes in the delegation.
3. Make sure your zone has NS Records.
4. Make sure your zone has A records or CNAME records for your web servers
5. Make sure your web server knows what to do with those host names
6. Make sure the name of your web site is not listed in the parent zone with an
incorrect glue record. For example, if your web site is www.example.com, make
sure the com zone doesn’t have an A record named www.example.com pointing to the wrong address.
7. Make sure your web site name is not listed in some other unrelated zone. For example, if your site is example.com.au, make sure there is no record for that with a different IP address in one of the root servers.

For example, it might be that the name 'example.com.au' was used as a name server in registering the domain 'example.org', and that some domain registrar employee then accidentally put an A record for 'example.com.au' in the root zone.
8. Check to see if there is any common denominator to the people what can’t find your domain. Look for thing like a common ISP. If you can isolate a common factor, check the DNS of that source.

Q: The registrar won’t let me register my domain name.
A:
1. Somebody else already owns it. Check the relevant whois database.
2. Some registrars perform consistency checks to make sure your zone data is correct. If that is the case, check the data very carefully before re-submitting because many such registrars charge a fee for resubmitting zones.