.info root servers responding in authority section, not answer section?

[R. Scott Perry]

We have a web site that runs tests on domain names ( 
http://www.dnsreport.com ), to check for some obvious DNS problems with 
domains.  It is not working properly with the .info domains.  The problem 
is that the root servers for .info (tld1.nominum.com and tld2.nominum.com) 
are answering NS queries for .info domains with 0 answers, placing the NS 
records in the authority section.  The DNS engine we use will report this 
as a "does not exist" condition.  The root servers for other TLDs will list 
the NS records in the answer section (with corresponding A records in the 
additional section).

For example:

Looking up the NS record for declude.com at a.gtld-servers.net returns 2 
answers (the NS records) and 2 additional records (the A records for the 
two nameservers in the answer section).

Looking up the NS record for declude.info at tld1.nominum.com returns 0 
answers, and the 2 NS records in the authority section.

Are both types of responses correct?  Why the inconsistency?  I checked a 
few RFCs (1034/1035/2181) and wasn't able to figure out what section covers 
this.
                                                       -Scott