miekg/godns — pull request #7 by dustywilson (2011-12-06 10:59:59+00:00)
Title: RRsetDeleteRR must set TTL to 0 otherwise BIND rejects with "FORMERR"

The file named/update.c.html in the BIND project tests the TTL immediately after seeing that "update_class == dns_rdataclass_none". See also http://www.fiveanddime.net/bind-9/bind-9.3.1/bin/named/update.c.html and search for the above conditional.