Книга: Fedora™ Unleashed, 2008 edition

Troubleshooting Problems in Zone Files

Troubleshooting Problems in Zone Files

The most common error in zone data is forgetting that names in a zone file are relative to the origin of the zone, not to the root. Writing www.example.com in the zone file for example.com and expecting it to be fully qualified causes names such as www.example.com.example.com to show up in the DNS. You should either write www, which is qualified to the correct www.example.com, or write www.example.com. (with the trailing period) to indicate that the name is fully qualified.

The SOA record should contain (as the first field) the domain name of the master server (not a CNAME) and a contact address (with the @ replaced by a .) to report problems to.

Mail sent to this address should be read frequently. The other fields should contain sensible values for your zone, and the serial number should be correctly incremented after each change.

As discussed earlier, A and PTR records should always match; that is, the A record pointed to by a PTR record should point back to the address of the PTR record. Remember to quote the two arguments of HINFO records if they contain any whitespace. Avoid the use of CNAME records for MX, NS, and SOA records.

In general, after making changes to zone data, it is a good idea to reload named and examine the logs for any errors that cause named to complain or reject the zone. Even better, you could use one of the verification tools, such as dnswalk, discussed briefly next.

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