Wow. It’s 2009, and apparently DNS can only support reading configuration file lines which are not greater than 255 characters. I received the following error in my system log when I was setting up DKIM entries:
Problem is, the entire domain is then borked. That is, if domain.dns contains all of the DNS records for example.com, this error makes the domain not found at all. Whoops.
Using domain server:
Host example.com not found: 3(NXDOMAIN)
Doh. Turns out, the syntax for including multi-line TXT records in named.conf is slightly obscure, but thanks to the folks at SFR Fresh, which hosts an open-source DKIM Milter, the syntax isn’t that difficult to master. In short, you include the text record by breaking it into smaller strings, and enclosing the whole thing with parenthesis.
“ing as an example” )
You get the idea.
Apparently DNS can support TXT records up to 65535 characters, but I’d say except in the cases of DKIM records, it’s rare to need this much data for a DNS record.