Subject: Re: name server problem NetBSD-current/stunos
To: None <,>
From: Don Lewis <>
List: current-users
Date: 04/29/1996 21:10:46
On Apr 29, 11:22am, wrote:
} Subject: Re: name server problem NetBSD-current/stunos
} NOTE:  I understand the phrase "inverse query" to mean "given IP address
} A.B.C.D, query the server and return a name".  If
} this is an incorrect assumption, kindly disregard this letter.

This is what RFC 1035 says about inverse queries:

    6.4. Inverse queries (Optional)
    Inverse queries are an optional part of the DNS.  Name servers are not
    required to support any form of inverse queries.  If a name server
    receives an inverse query that it does not support, it returns an error
    response with the "Not Implemented" error set in the header.  While
    inverse query support is optional, all name servers must be at least
    able to return the error response.
    6.4.1. The contents of inverse queries and responses          Inverse
    queries reverse the mappings performed by standard query operations;
    while a standard query maps a domain name to a resource, an inverse
    query maps a resource to a domain name.  For example, a standard query
    might bind a domain name to a host address; the corresponding inverse
    query binds the host address to a domain name.
    Inverse queries take the form of a single RR in the answer section of
    the message, with an empty question section.  The owner name of the
    query RR and its TTL are not significant.  The response carries
    questions in the question section which identify all names possessing
    the query RR WHICH THE NAME SERVER KNOWS.  Since no name server knows
    about all of the domain name space, the response can never be assumed to
    be complete.  Thus inverse queries are primarily useful for database
    management and debugging activities.  Inverse queries are NOT an
    acceptable method of mapping host addresses to host names; use the IN-
    ADDR.ARPA domain instead.

			---  Truck