The class of a DNS response object. When dns-query is called with the
decode argument nil, the
response from the nameserver is returned in its raw form. The response
is represented by a dns-response object which contains
pointers to dns-rr
objects. It has the following slots and accessors:
id, accessor is dns-response-id. The number of the query
for which this is a response. Each query is given a unique number by
dns-query so that it
can associate responses with queries.
flags, accessor is dns-response-flags. The characteristics
of the response are described by a set of flags represented it this
slot by a list of keyword symbols. The set of flags can be found in
rfc1035, the document describing the DNS specification (see The Allegro CL Domain Naming System
Package in dns.htm for a link to
rfc1035).
flags-value, accessor is dns-response-flags-value. An integer
that is the raw form of the flags value.
answer, accessor is dns-response-answer. A list of dns-rr objects which
comprise the answer to the query. If there are no answers than that
is significant as well as that tells you that what you're asking for
either doesn't exist or can't be computed at this time.
authority, accessor is dns-response-authority. DNS permits
nameservers to cache information and this is in fact critical to
prevent nameserver overloading. What this means though is that the
same information can be stored in a large collection of nameservers.
However for any piece of information there is always a set of
nameservers that are the authoritative nameservers for that
information. This field in the dns-response lists the nameservers that
are the authority for answering the dns-query that was posed. The
nameservers are returned as a list of dns-rr objects.
additional, accessor is dns-response-additional. Some queries
return answers which would immediately prompt another query. For
example a :type :mx dns-query to find a mail
exchanger for a name returns a set of mail exchanger machine names.
After receiving those names the program will almost certainly want to
find the IP addresses for those machine names. Thus the DNS system can
anticipate the follow up query and can return in the additional slot a
list of dns-rr's
that would be returned by the followup query. In the :type
:mx query the additional slot usually contains a list of
those mail exchangers machine names and their IP addresses. There is
no guarantee that that information will be provided in the additional
slot
See dns.htm.
The documentation is described in introduction.htm and the index is in index.htm.
Copyright (c) 1998-2000, Franz Inc. Berkeley, CA., USA. All rights reserved.
Created 2000.10.5.