Re: [opensuse] Ipv6 and dns

On Tue, 29 May 2012 21:33:13 +0200
Per Jessen <per@xxxxxxxxxxxx> wrote:

Carl Hartung wrote:

On Tue, 29 May 2012 19:33:59 +0200
Per Jessen <per@xxxxxxxxxxxx> wrote:

[snip]

We're not talking about responses going over IPv6, but about
responses with AAAA DNS records (which happen to be IPv6
addresses). The actual communication might happen over IPv4, -5 or
-6 or even carrier pigeon (RFC1149). :-)


I get this part, Per. I really do - at least I /thought/ I did. This
explains why, when I run a query via cli from my IPv4 network, I get
back a listing containing both addresses (if the IPv6 address
exists.)

Exactly.

But that's a diagnostic procedure, right?

Nope.

It isn't an exact replacement for the 'live' transaction that occurs
between, say, a browser on an IPv4 network and a DNS server
configured for, and residing on, an IPv6 network, right? IOW, in
everyday operation, if a request arrives at an IPv6 enabled server
on IPv4 port 53, the fact that it arrives at the IPv4 address
results in the IPv4 address, alone, being returned - the rational
being it is presumed that the client is unable to use the IPv6
address.

Am I way out past left field here today? :-)

Yeah ...
how a DNS query arrives will at most determine how the response will
be sent back. Whether a DNS query arrives via IPv4 or IPv6 does not
in any way determine what the response contains.



So the server sends back two records instead of one, and the client just
discards the one it can't use. That's not very efficient (stupid
server!) Thanks for the clarification ;-)
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