[dns-operations] who cares about RA bit

[Mark Andrews]

Stub resolvers expect recursive service.  Some answers get
mis-interpretted if they don't get recursive service.  Some resolver
libraries will skip servers that do not set RA in responses to
queries with RD set.  If the caller of the library has requested
recursive service then the library has to ensure that the answer
returned is complete and the only way it can determine that is to
look for RA.  If they don't see RA they move onto the next nameserver
listed in resolv.conf or the equivalent.

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