[dnsext] tsv-dir review of draft-ietf-dnsext-dns-tcp-requirements (DNS Transport over TCP - Implementation Requirements) to Proposed Standard

[David Borman <[e-mail]>]

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I've reviewed this document as part of the transport area directorate's
ongoing effort to review key IETF documents. These comments were written
primarily for the transport area directors, but are copied to the
document's authors for their information and to allow them to address
any issues raised. The authors should consider this review together
with any other last-call comments they receive. Please always CC
[e-mail] if you reply to or forward this review.

Summary
-------

The primary purpose of this document is stated in the abstract:

   This document updates the requirements for the support of TCP as a
   transport protocol for DNS implementations.

As such, it does not introduce any changes to how DNS operates over TCP.
Additions since the original DNS specification have extended the amount
of information that can be communicated, and if there is too much data
sent in a UDP packet it will be truncated at 512 bytes.  Using TCP as
the transport instead of UDP avoids this truncation.

The document also recommends that dormant connections be closed on the
order of seconds, rather than minutes, as in the original specification,
to avoid tying up resources.

This document also clarifies that client resolvers must be able to process
responses that arrive in a different order than they were sent, regardless
of what transport is used.

Comments and recommendations:
-----------------------------
I do not see any transport related issues with this document.  As the
summary states, this document is mostly about maing DNS over TCP a must
for implementors, and clarifying some minor items in the original DNS
specification.  So from that standpoint I have no concerns with the
publication of this document.

			-David Borman, [e-mail]