Common DNS syntax errors

These are 2 of the most common syntax errors I see in DNS records.

1. Any entry with a fully qulified domain name needs a trailing period.
2. Any TXT entry needs to have the value in double quotation marks ” “

For example on the fully qualified domain names, these are wrong:

domain.com IN A 91.216.241.52
www.domain.com IN CNAME someotherdomain.com

The reason they are wrong is domain.com www.domain.com and someotherdomain.com should all have periods at the end like this:

domain.com. IN A 91.216.241.52
www.domain.com. IN CNAME someotherdomain.com.

Another rule to keep in mind is that a sub domain that is not fully qualified does not need a trailing period.  For example:

www IN CNAME someotherdomain.com.

That is correct.  The reason for the period is this.  If you do not include a period, then the name server will automatically append .domain.com to the end of the entry.  so domain.com becomes domain.com.domain.com.  This is why www without a period works, because www becomes www.domain.com.

For TXT records, it’s fairly simple.  Put the value in ” ” (double quotation marks).

This entry is wrong:

domain.com. 3600    IN      TXT     MS=ms12345678

This entry is correct:

domain.com. 3600    IN      TXT     “MS=ms12345678”