Subject: [v6ops] Mobile: Happy DNSclientBalls

From: Thor-Henrik Kvandahl <[email-masked]>
Date: Thu, 11 Jan 2018 08:46:12 +0100

Hi,

Does anyone know if there are defined requirements on behaviour for the DNS
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*

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From: Erik Kline <[email-masked]>
Date: Thu, 11 Jan 2018 16:57:30 +0900

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 <[email-masked]> wrote:
> 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?
>
> 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
> Thor-Henrik Kvandahl
> _______________________________________________
> v6ops mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/v6ops
>

---

From: Thor-Henrik Kvandahl <[email-masked]>
Date: Thu, 11 Jan 2018 12:47:57 +0100

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 <https://tools.ietf.org/html/rfc8305#section-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 <[email-masked]>:

> 3gpp

---

From: Erik Kline <[email-masked]>
Date: Thu, 11 Jan 2018 21:06:30 +0900

You can "expect a change" in the sense that it is something we want to
fix.  When it is ultimately fixed it will effectively only apply to
releases going forward from the date of the fix (i.e. it will not be
backported to contemporaneous nor prior releases).

On 11 January 2018 at 20:47, Thor-Henrik Kvandahl <[email-masked]> wrote:
> 3.1.  Handling Multiple DNS Server Addresses
>