In message
<AANLkTiknLr5c5nKc8ewWvi9-H1ZmvQybMFArReRj7h_3(_at_)mail(_dot_)gmail(_dot_)com>,
Phil
lip Hallam-Baker writes:
Nah, the service provider tells the client what to use via SRV records.
In most cases the service provider is going to know if IPv4 or IPv6 is going
to work better. They use different DNS names for the v4 and v6 interfaces
and prioritize them accordingly.
In most cases though the server is going to be IPv4 only or have equally
good IPv4 and IPv6.
On the client end the client is going to have a consistently better
experience with v4 or v6. And that information can be used to inform the
choice when making future connections.
With well connected clients. For clients with connectivity problems
it can matter.
The only case where I can see a client preferring IPv6 over 4 is when they
are behind a super-NAT and the v4 service is degraded. Or when they are
attempting to accept an incoming connection for VOIP or video conferencing.
Super-NAT's will become common place.
You also want to prefer IPv6 over IPv4 so that one can see when you
can stop supporting IPv4 by looking at the traffic levels. Code will
be used for decades after it is written. You need to write code for
the end state even if it is painful at the beginning.
The key is to take the decision out of the hands of the application software
so that it can be taken by the platform and allow the experience from one
connection to be used to inform the choice made on the next.
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka(_at_)isc(_dot_)org
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