Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended-error-05.txt

Puneet Sood <> Wed, 13 March 2019 21:02 UTC

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From: Puneet Sood <>
Date: Wed, 13 Mar 2019 17:02:41 -0400
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Subject: Re: [DNSOP] I-D Action: draft-ietf-dnsop-extended-error-05.txt
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My comments on the latest version.

General: Thanks for writing this - it provides useful information for
our public DNS resolver implementation.

> Section 1. Introduction and background
> Para 4. "Authoritative servers MAY parse and use them ..."
Comment: Why talk about auth servers parsing this since this field is
only meant to be present in responses?

> Section 3.1 The R (retry) flag
> Para  2. "implementations may receive EDE codes that it does not understand.
>   The R flag allows implementations to make a decision as to what to do
>   if it receives a response with an unknown code - retry or drop the
>   query."

Comment: It is unclear what should be done if a response contains
multiple EDE options and the R flag value is different across them.

Comment: On a related note, what is the reasoning for allowing
multiple instance of the EDE option in a response versus encoding all
the (Response-CODE, INFO-CODE, EXTRA-TEXT) tuples in a single EDE
option? A single EDE option would avoid having different values for
the R flag and any new flag in the future. 16-bit length field means
that total size of all EDE options should fit in a single option.

> Section 4.1.3 and NOERROR Extended DNS Error Code 3 - Stale Answer
Comment: should be 4.1.3?

> Section 4.2 INFO-CODEs for use with RESPONSE-CODE: SERVFAIL(2)
Comment: There are a number of INFO-CODEs here for DNSSEC failures.
Over time it will be extra work for implementations to stay up to date
with new INFO-CODEs added for DNSSEC failures. The R bit signals
whether a resolution should be retried. Do we want also want a bit for
signalling DNSSEC validation failures? Only needed if some DNSSEC
related behavior needs to be different from the R bit value.

> Section 6. Security Considerations
> Para 2: "but until we live in
>   an era where all DNS answers are authenticated via DNSSEC or other
>   mechanisms, there are some tradeoffs."
Comment: Not clear how DNSSEC would help here since the OPT RR is not
protected by any DNSSEC mechanism.

> Appendix A.
Editorial: Missing diff summaries for new versions.


On Mon, Mar 11, 2019 at 6:09 PM <> wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Domain Name System Operations WG of the IETF.
>         Title           : Extended DNS Errors
>         Authors         : Warren Kumari
>                           Evan Hunt
>                           Roy Arends
>                           Wes Hardaker
>                           David C Lawrence
>         Filename        : draft-ietf-dnsop-extended-error-05.txt
>         Pages           : 15
>         Date            : 2019-03-11
> Abstract:
>    This document defines an extensible method to return additional
>    information about the cause of DNS errors.  Though created primarily
>    to extend SERVFAIL to provide additional information about the cause
>    of DNS and DNSSEC failures, the Extended DNS Errors option defined in
>    this document allows all response types to contain extended error
>    information.
> The IETF datatracker status page for this draft is:
> There are also htmlized versions available at:
> A diff from the previous version is available at:
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at
> Internet-Drafts are also available by anonymous FTP at:
> _______________________________________________
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