inverse query:PTR RR or OPCODE=1 ?
marka at isc.org
Thu Dec 3 03:03:03 UTC 2009
In message <4591889.164031259808158905.JavaMail.coremail at app183.163.com>, lipen
> when I read the RFC1035, I noticed the opcode defination in the DNS
> message head . It said that when opcode = 1 the message did Inverse query.
> but in the packet I capatured when I used nslookup to do inverse query
> ,the inverse query packet use the opcode = 0 and the question segment with
> RR TYPE PTR. Can someone explain this ? Am I wrong about understanding the
> inverse query ? Thank a lot .
Nslookup does normal queries into the .ARPA namespace to do "reverse"
Inverse lookups were a concept that really only worked in the "dentist
surgery" senario (one server providing the entire DNS view). Inverse
queries were deprecated years ago <http://www.ietf.org/rfc/rfc3425.txt>.
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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