Subject: Proposed resolution to LLMNR Issue 21

From: Bernard Aboba <[email-masked]>
Date: Mon, 17 Mar 2003 09:57:25 -0800 (PST)

Issue 21: PTR queries
Submitter: Markku Savela
Submitter email address: [email-masked]
Date first submitted: November 4, 2002
Reference: <[email-masked]>
Document: LLMNR-12
Comment type: T
Priority: S
Section: Various
Rationale/Explanation of issue:
I assume that if you end up doing a address (fe80::1) to name query
for IPv6, you end up sending a query to IPv6 multicast address
generated from the hash of

"1.0.0. ... 0.0.8.e.f.ip6.int"

and because the hash is taken from the first label, this will be MD5
from "1"? (basically only 16 different hashes are possible).

IPv4 side you have for example "1.2.254.169.in-addr.arpa".

Am I right assuming the "resolvers" on nodes have to deal also with
these for link local name resolution?
[BA] Yes, it is expected that senders will send PTR
queries, and that receivers will respond to them.
However, it probably doesn't make sense to send a
PTR query for an address that isn't on the local
link. Here's the proposed resolution:

Add the following text to Section 3:

"[3] A sender SHOULD NOT send LLMNR queries for PTR RRs that
correspond to addresses known not to exist on the local link.
Since legitimate responses to LLMNR queries can only come from
hosts on the local link, an LLMNR query for an address not
on the local link cannot elicit a legitimate response."

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