RFC 1183 (rfc1183) - Page 2 of 11

New DNS RR Definitions

RFC 1183                 New DNS RR Definitions             October 1990


1. AFS Data Base location

   This section defines an extension of the DNS to locate servers both
   for AFS (AFS is a registered trademark of Transarc Corporation) and
   for the Open Software Foundation's (OSF) Distributed Computing
   Environment (DCE) authenticated naming system using HP/Apollo's NCA,
   both to be components of the OSF DCE.  The discussion assumes that
   the reader is familiar with AFS [5] and NCA [6].

   The AFS (originally the Andrew File System) system uses the DNS to
   map from a domain name to the name of an AFS cell database server.
   The DCE Naming service uses the DNS for a similar function: mapping
   from the domain name of a cell to authenticated name servers for that
   cell.  The method uses a new RR type with mnemonic AFSDB and type
   code of 18 (decimal).

   AFSDB has the following format:

    AFSDB 

   Both RDATA fields are required in all AFSDB RRs.  The  field
   is a 16 bit integer.  The  field is a domain name of a host
   that has a server for the cell named by the owner name of the RR.

   The format of the AFSDB RR is class insensitive.  AFSDB records cause
   type A additional section processing for .  This, in fact,
   is the rationale for using a new type code, rather than trying to
   build the same functionality with TXT RRs.

   Note that the format of AFSDB in a master file is identical to MX.
   For purposes of the DNS itself, the subtype is merely an integer.
   The present subtype semantics are discussed below, but changes are
   possible and will be announced in subsequent RFCs.

   In the case of subtype 1, the host has an AFS version 3.0 Volume
   Location Server for the named AFS cell.  In the case of subtype 2,
   the host has an authenticated name server holding the cell-root
   directory node for the named DCE/NCA cell.

   The use of subtypes is motivated by two considerations.  First, the
   space of DNS RR types is limited.  Second, the services provided are
   sufficiently distinct that it would continue to be confusing for a
   client to attempt to connect to a cell's servers using the protocol
   for one service, if the cell offered only the other service.

   As an example of the use of this RR, suppose that the Toaster
   Corporation has deployed AFS 3.0 but not (yet) the OSF's DCE.  Their
   cell, named toaster.com, has three "AFS 3.0 cell database server"



Everhart, Mamakos, Ullmann & Mockapetris