Applicability Statement for DNS MIB Extensions (RFC3197)
Original Publication Date: 2001-Nov-01
Included in the Prior Art Database: 2001-Nov-28
Internet Society Requests For Comment (RFCs)
This document explains why, after more than six years as proposed standards, the DNS Server and Resolver MIB extensions were never deployed, and recommends retiring these MIB extensions by moving them to Historical status.
Network Working Group R. Austein
Request for Comments: 3197 InterNetShare
Category: Informational November 2001
Applicability Statement for DNS MIB Extensions
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright (C) The Internet Society (2001). All Rights Reserved.
This document explains why, after more than six years as proposed
standards, the DNS Server and Resolver MIB extensions were never
deployed, and recommends retiring these MIB extensions by moving them
to Historical status.
The road to the DNS MIB extensions was paved with good intentions.
In retrospect, it's obvious that the working group never had much
agreement on what belonged in the MIB extensions, just that we should
have some. This happened during the height of the craze for MIB
extensions in virtually every protocol that the IETF was working on
at the time, so the question of why we were doing this in the first
place never got a lot of scrutiny. Very late in the development
cycle we discovered that much of the support for writing the MIB
extensions in the first place had come from people who wanted to use
SNMP SET operations to update DNS zones on the fly. Examination of
the security model involved, however, led us to conclude that this
was not a good way to do dynamic update and that a separate DNS
Dynamic Update protocol would be necessary.
The MIB extensions started out being fairly specific to one
particular DNS implementation (BIND-4.8.3); as work progressed, the
BIND-specific portions were rewritten to be as implementation-neutral
as we knew how to make them, but somehow every revision of the MIB
extensions managed to create new counters that just happened to
closely match statistics kept by some version of BIND. As a result,
the MIB extensions ended up being much too big, which raised a number
Austein Informational [Page 1]
RFC 3197 Applicability Statement - DNS MIB Extensions November 2001
of concerns with the network management directorate, but the WG
resisted every attempt to remove any of these variables. In the end,
large portions of the MIB extensions were moved into optional groups
in an attempt to get the required subset down to a manageable size.
The DNS Server and Resolver MIB extensions were one of the first
attempts to write MIB extensions for a protocol usually considered to
be at the application layer. Fairly early on it became clear that,
while it was certainly possible to write MIB extensions for DNS, the
SMI was not really designed with this sort of thing in mind. A case
in point was the attempt to provide direct indexing into the caches
in the resolver MIB extensions: while arguably the only sane way to
do this for a large cache, this required much more complex indexing
clauses than is usual, and ended up running into known length limits
for object identifiers in some SNMP implementatio...