Recently a customer created an CNAME record for in their cPanel but the changes were not taking effect. When looking in /var/log/messages, I was seeing an error like this:
/var/named/domain.com.db:22: ignoring out-of-zone data (some.subdomain.com)
The cname they added looked like this
sales. 14400 IN CNAME some.subdomain.com.
The reason this was wrong, was the customer mistakenly put a “.” after the word sales. Periods should only show up after fully qualified domain names. For example, if they had put sales.domain.com then they would put a period. However, since the customer was just putting sales, it should not have a period.
The period signifies the end of the data. If you do not put a period, then the DNS server will append .domain.com on to the end of the record. So sales without a period ends up becoming sales.domain.com. When a period was placed at the end of sales, the DNS server read it ONLY as sales, which is not the domain name, so it gives the out-of-zone data error.