[dns-operations] NS answer inconsistency between implementations for delegated zone

[Mark Andrews]

BIND 8 did it both ways depending apon whether RD was set or not
and whether we offered recursion.  RD=0 or we didn't offer recursion
then a delegation was returned.  If recursion was desired and it
was available then a answer was returned.  This was a compromise
due to using a single database for both the cache and authoritative
data.

Nameserver, when iterating, don't set RA so referral were returned
to them.   Stub resolvers (which dig emulates by default) got answers.

BIND 9 has code to detect referrals promoted to answer and treat
them as referrals.

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org