Authority and Additional sections (was Re: bind vs djbdns)

Tue Sep 5 23:23:35 UTC 2000

RFC 1034 has several examples of answers with empty AU/AR sections. The
Microsoft DNS example is fine.

Kevin's suggestion for BIND 9 is how djbdns already works. Responses
from caches don't include AU/AR. Responses to caches include AU/AR so
that smart caches can avoid unnecessary requests to parent servers. But
this isn't required.

BIND's AU/AR behavior, on the other hand, violates the RFCs. BIND
repeats an RR set from AN to AR in the following situation:

   % dnsq a ns-ext.vix.com ns-ext.vix.com
   1 ns-ext.vix.com:
   117 bytes, 1+1+2+2 records, response, authoritative, noerror
   query: 1 ns-ext.vix.com
   answer: ns-ext.vix.com 3600 A 204.152.184.64
   authority: vix.com 3600 NS ns-ext.vix.com
   authority: vix.com 3600 NS ns1.gnac.com
   additional: ns-ext.vix.com 3600 A 204.152.184.64
   additional: ns1.gnac.com 657 A 209.182.195.77
   %

This blatantly violates section 5.5 of RFC 2181. Beware that you'll
misinterpret section 5.5 if you haven't read section 3.

---Dan