Subject: localhost. & 127.0.0.1

From: Edward Lewis <[email-masked]>
Date: Tue, 28 Dec 1999 09:02:29 -0500

First a disclaimer, I'm not certain this is a topic for the working group.
A few of us, working through the fairly quite holoday period, got to
talking about localhost.  We decided to see what the "roots" said on the
subject.

What is interesting is that for the reverse map, there are three different
answers, with a fairly even distibution among them (and one answer
particular to one server).  I understand the referral on j, k, and m, as
they aren't arpa. servers.

Is there some reason to cover this in the root server requirements
document?  This is a fairly idle question, my own answer is probably not.
I don't imagine that these queries reach the root servers all that often.
If these queries do, it's from some nut like me doing a test, or someone
with broken configurations - hence larger problems.  On the other hand, if
we are talking about having servers share addressed and are worried about
consistency of answers, this may be an issue.

*Shrug.*

FWIW, The question of how to sign localhost has come up in DNS security
extensions discussions, without any attempt at a definitive answer.

  ----------------------- ------------------------ -----------------------

Query for 127.0.0.1's PTR record:

"localhost.": g, e, c, b (latter's answer is only one in upper case)
NXDOMAIN: i, h, f, d, a
Referral to the arpa. server: m, k, j
Just plain wrong (LOCALHOST.0.0.127.in-addr.arpa.): l

Delegations to 0.0.127.in-addr.arpa: b e g l
Delegations to 127.in-addr.arpa: c
Delegations to in-addr.arpa: a d f h i
Delegations to arpa.: j k m

query for localhost. A record:

NXDOMAIN for all but c
"127.0.0.1" on server c

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Edward Lewis                                                NAI Labs
Phone: +1 443-259-2352                      Email: [email-masked]

"Trying is the first step to failure." - Homer Simpson
"No! Try not. Do... or do not. There is no try." - Yoda

Opinions expressed are property of my evil twin, not my employer.