Re: [v6ops] An Update to Happy Eyeballs

Philip Homburg <pch-v6ops-7@u-1.phicoh.com> Wed, 22 March 2017 22:22 UTC

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Date: Wed, 22 Mar 2017 23:22:38 +0100
Archived-At: <https://mailarchive.ietf.org/arch/msg/v6ops/AUXrlTXSqvuxCBdNl4_CmEWBBRU>
Subject: Re: [v6ops] An Update to Happy Eyeballs
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>You don't have to use getaddrinfo to do AAAA lookups. You can use your own
>code, or even pass binary blobs to res_send if you want.
>
>getaddrinfo is not very smart. It keeps trying until it has answers for
>everything you asked it to do, and then it returns everything. That means
>that if the A query is in cache and the AAAA query is not, then you have to
>wait for the AAAA query to succeed.
>
>I think the key point here is that integrating the DNS resolver retry loops
>with the connection attempts provide latency savings.

What is next? Is this working group going to specify how SMTP clients should
do MX lookups?

Why is how to do DNS lookups suddenly something v6ops has to write a BCP
about?

Next question. If an A record happens to be cached and an operator wants
to keep traffic out of expensive CGNAT routers. Do we really want to 
encourage hosts to connect over IPv4 just because an A record was cached
and the AAAA record wasn't? Is that really best current practice?