Re: [v6ops] Mobile: Happy DNSclientBalls

Thor-Henrik Kvandahl <> Thu, 11 January 2018 11:48 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id B3DAB12EB0B for <>; Thu, 11 Jan 2018 03:48:06 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.698
X-Spam-Status: No, score=-2.698 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id uRRP1YvGTmgp for <>; Thu, 11 Jan 2018 03:48:04 -0800 (PST)
Received: from ( [IPv6:2a00:1450:4010:c07::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 0EB0612EB20 for <>; Thu, 11 Jan 2018 03:47:59 -0800 (PST)
Received: by with SMTP id h5so2457831lfj.2 for <>; Thu, 11 Jan 2018 03:47:59 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=swedUqsjSOzK1GE+1tO+qvAid1B7MQ1nuGtWi8CaFuk=; b=L4xdn2h8hU4qvlRTPVpMfBs7R6D29wWuh3urqYcn6WWhR7F1L7Y3ADYJhE004PXgy9 eEWrIytzOsHOsgPbtd0HGq4PEBv8DVfYu9pQazTP889z3J+uq1aumeEnsXGAcahaHZVJ hX1o+ONBwLtycRU4s5/qU3VewZqpYOab4c8m3bsxRYvcAF1f5nGc1FA9bDADRgiEehmc Rdzv3hO49Uc0LXiB8PTnZznWx2HB+oBnMn5CKIZ6MXQ2JfhZRvfBa5SZcIDrM3sQOio4 LgzptRnFe4fd/kS8lxcBoO0bCn4v5IG9q+drDIKx2jZKCYkrC/yS1KO60O08uxRhL7aE s6kQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=swedUqsjSOzK1GE+1tO+qvAid1B7MQ1nuGtWi8CaFuk=; b=n7doTN4XYQe18WeuNYrYDQxb66ESxswANE3BOsfe4VmmxdvFmBWoa+3JZCXcDVdTbS BYP3Wt9K7Zjdjj+Y71qiU2tUsOPutwvXmukRpA5dkW5rfsPpIV6dpw/LF5pfvOmXSvA2 hQ2FOJhgB1lRFV5VveF6o7YfELxIkTULDvbq8uXczWy5BsIYHzlRrLv7LopYIsJnFhwl JEmjYqcri+fmmUrKnn3YXcvNW6UQszefjhrm9Gz14GYBndpB3l+bOlwxtFilaDSgkQ4k 3Dd9QY2XOQZqIbvS/iV6C5HiA3kvoqOqIFU7QrnKTlntpUTY0ER1+XBeUUBLAuKAOZtn OvQg==
X-Gm-Message-State: AKGB3mKlqvhmzwrMq2oUHSGlSopGrEHmudjROXjSshkDw0LWky50wc1F VhmJn1pQ1xblqwwt1Ktm8ekIvpt1OA4RkURYny2SfUzQ
X-Google-Smtp-Source: ACJfBot+CGZUd6hzHjtajESLs5be5YbswPoSm0B20vWN/v6ZTPSB6EaWjFLxYLkYG4Qt8ftnU6EDOWdM47r0TxKyOJ8=
X-Received: by with SMTP id s23mr12585434lje.50.1515671277858; Thu, 11 Jan 2018 03:47:57 -0800 (PST)
MIME-Version: 1.0
Received: by with HTTP; Thu, 11 Jan 2018 03:47:57 -0800 (PST)
In-Reply-To: <>
References: <> <>
From: Thor-Henrik Kvandahl <>
Date: Thu, 11 Jan 2018 12:47:57 +0100
Message-ID: <>
To: Erik Kline <>
Cc: " WG" <>
Content-Type: multipart/alternative; boundary="94eb2c1aa6941cf30b05627eb89f"
Archived-At: <>
Subject: Re: [v6ops] Mobile: Happy DNSclientBalls
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: v6ops discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 11 Jan 2018 11:48:07 -0000

Actually, in the updated "Happy Eyeballs" RFC8305, handling of multiple DNS
server addresses are addressed and "queries SHOULD be sent over IPv6 first".
Also you say Google has an open bug on RFC6724, sorting of nameservers.
If I understand the RFCs correct, Android Oreo and Nougat (and also older?)
terminals should change behavior and prefer IPv6 nameservers.
Is this correct and can we expect a change ?

3.1 <>.  Handling
Multiple DNS Server Addresses

   "If multiple DNS server addresses are configured for the current
   network, the client may have the option of sending its DNS queries
   over IPv4 or IPv6.  In keeping with the Happy Eyeballs approach,
   queries SHOULD be sent over IPv6 first (note that this is not
   referring to the sending of AAAA or A queries, but rather the address
   of the DNS server itself and IP version used to transport DNS
   messages).  If DNS queries sent to the IPv6 address do not receive
   responses, that address may be marked as penalized and queries can be
   sent to other DNS server addresses.

   As native IPv6 deployments become more prevalent and IPv4 addresses
   are exhausted, it is expected that IPv6 connectivity will have
   preferential treatment within networks.  If a DNS server is
   configured to be accessible over IPv6, IPv6 should be assumed to be
   the preferred address family.

   Client systems SHOULD NOT have an explicit limit to the number of DNS
   servers that can be configured, either manually or by the network.
   If such a limit is required by hardware limitations, the client
   SHOULD use at least one address from each address family from the
   available list."


*Thor-Henrik Kvandahl*

2018-01-11 8:57 GMT+01:00 Erik Kline <>:

> We have an open bug to do RFC6724 sorting of nameservers.  Haven't
> gotten around to it just yet.
> As far as requirements go, I'm not aware of anything off the top of my
> head.  Carriers can (and do) try to require whatever they can dream
> up, but that's separate.
> On 11 January 2018 at 16:46, Thor-Henrik Kvandahl <>
> wrote:
> > Hi,
> >
> >
> >
> > Does anyone know if there are defined requirements on behaviour for the
> > client on a Mobile Node (MN/UE) connected to a dual stack APN where the
> 3gpp
> > IE container provisioned both IPv4 and IPv6 name servers?
> >
> > As far as I know it is up to the UE to prefer between the provisioned
> name
> > servers, and I think they should prefer IPv6 name servers.
> > My Android Oreo and Nougat DNS clients uses only IPv4 for DNS requests
> and I
> > think it would be better for the NAT44(4) devices between the PGW and the
> > resolver if the UE preferred to use the IPv6 name server(s).
> >
> > If there are no requirements for this, does anyone know the Google policy
> > for Android on this?
> >
> > Iphone's seems to prefer the IPv6 name servers.
> >
> >
> >
> >
> > --
> >
> > Thor-Henrik Kvandahl
> >
> > _______________________________________________
> > v6ops mailing list
> >
> >
> >