The previous port of Knot DNS, dns/knot1, is starting to complain about build failouts.
As I expect all users already migrated to dns/knot2 I'm convinced that deleting the port is the best solution.
I tried to make a patch to do so, but it didn't look too useful.
A commit references this bug:
Date: Sun Nov 18 08:01:37 UTC 2018
New revision: 485217
Mark DEPRECATED. EOL upstream, and successor already in place
Reported by: email@example.com (maintainer)
Expired port removed.