Re: [Gen-art] Genart last call review of draft-ietf-dnsop-dns-tcp-requirements-12

[Dan Romascanu <[e-mail]>]

Hi Duane,

Thank you for your answer and for addressing my concerns. I am fine with
the proposed resolutions.

Regards,

Dan


On Tue, Sep 7, 2021 at 7:46 PM Wessels, Duane <[e-mail]> wrote:

> Dan, thanks for the review.  Responses are inline.
>
>
>
> > On Sep 1, 2021, at 3:12 AM, Dan Romascanu via Datatracker <
> [e-mail]> wrote:
> >
> >
> > Minor issues:
> >
> > 1. In Section 4.1:
> >
> >> DNS clients MAY also enable TFO when possible.
> >
> > Maybe I do not fully understand the intent here, but 'MAY ... when
> possible'
> > sounds like a SHOULD to me.
>
>
> Originally this was "SHOULD ...  when possible" (meaning when
> implemented/supported) but after conversations with tcpm this was changed
> to MAY.  To avoid confusion with "when possible" I suggest we just drop
> it so it will just say "DNS clients MAY also enable TFO."
>
>
>
> >
> > 2.In Section 4.2
> >
> >>  DNS server software SHOULD provide a configurable limit on the total
> >   number of established TCP connections.  If the limit is reached, the
> >   application is expected to either close existing (idle) connections
> >   or refuse new connections.  Operators SHOULD ensure the limit is
> >   configured appropriately for their particular situation.
> >
> >   DNS server software MAY provide a configurable limit on the number of
> >   established connections per source IP address or subnet.  This can be
> >   used to ensure that a single or small set of users cannot consume all
> >   TCP resources and deny service to other users.  Operators SHOULD
> >   ensure this limit is configured appropriately, based on their number
> >   of diversity of users.
> >
> > The lack of recommendations about how these limits should be set would
> leave
> > less experienced operators in the dark. There is not even a sentence
> like 'This
> > document does not offer advice on particular values for such a limit' as
> for
> > other parameters in the same section. From an operators point of view I
> would
> > prefer a recommendation or one or more examples of how these limits can
> be set
> > in real life cases.
>
> Other reviewers called this out as well so I have added some recommended
> values.
>
> For the limit on total number of connections: "Absent any other
> information,
> 150 is a reasonable value for this limit in most cases."
>
> For the limit on connections per source address: "Absent any other
> information, 25 is a reasonable value for this limit in most cases."
>
> For the timeout on idle connections: "Absent any other information, 10
> seconds is a reasonable value for this timeout in most cases."
>
>
> >
> > Nits/editorial comments:
> >
> > 1. Sections in the document that are obviously for informational
> pursposes
> > should be clearly marked so (like 'This section is included for
> informational
> > purposes only'). For example Section 2.
>
> Done.
>
>
> >
> > 2. In Section 3:
> >
> > Regarding the choice of limiting the resources a server devotes to
> >   queries, Section 6.1.3.2 in [RFC1123] also says:
> >
> >      "A name server MAY limit the resources it devotes to TCP queries,
> >      but it SHOULD NOT refuse to service a TCP query just because it
> >      would have succeeded with UDP."
> >
> >   This requirement is hereby updated: A name server MAY limit the
> >   resources it devotes to queries, but it MUST NOT refuse to service a
> >   query just because it would have succeeded with another transport
> >   protocol.
> >
> > Similar alignment of the old and new text is desirable. Even using the
> OLD /
> > NEW format.
>
> Good point.  Section 3 now looks like this:
>
>    Section 6.1.3.2 in [RFC1123] is updated: All DNS resolvers and
>    servers MUST support and service both UDP and TCP queries.
>
>    o  Authoritative servers MUST support and service all TCP queries so
>       that they do not limit the size of responses to what fits in a
>       single UDP packet.
>
>    o  Recursive servers (or forwarders) MUST support and service all TCP
>       queries so that they do not prevent large responses from a TCP-
>       capable server from reaching its TCP-capable clients.
>
>    Furthermore, the requirement in Section 6.1.3.2 of [RFC1123] around
>    limiting the resources a server devotes to queries is hereby updated:
>
>    OLD:
>
>       A name server MAY limit the resources it devotes to TCP queries,
>       but it SHOULD NOT refuse to service a TCP query just because it
>       would have succeeded with UDP.
>
>    NEW:
>
>       A name server MAY limit the resources it devotes to queries, but
>       it MUST NOT refuse to service a query just because it would have
>       succeeded with another transport protocol.
>
>
>
> FYI we are tracking this in github at
> https://github.com/jtkristoff/draft-ietf-dnsop-dns-tcp-requirements/pull/4/files
> if that is helpful.
>
> DW
>
>