[ntp:questions] IPv6 vs IPv4 look-ups (Was: Re: http://www.ntp.org/ => a blank page?)

Rob nomail at example.com
Thu Mar 5 14:11:21 UTC 2009

Steve Kostecke <kostecke at ntp.org> wrote:
> On 2009-03-05, Martin Burnicki <martin.burnicki at meinberg.de> wrote:
>> The IPv4 address is used only after the IPv6 address has timed out, even
>> though (as far as I understand it) the DNS server first returns an IPv4
>> address, then an IPv6 address:
>> # host support.ntp.org
>> support.ntp.org has address
>> support.ntp.org has IPv6 address 2001:4f8:0:2::23
> On my LAN I see:
> $ host support.ntp.org
> support.ntp.org     	A
> To resolve the IPv6 address:
> $ aaaa support.ntp.org
> support.ntp.org     	AAAA	2001:4F8:0:2:0:0:0:23
> Both 'host' and 'aaaa' are a part of the Debian host package. The
> version I have installed is:
>||/ Name         Version       Description
> +++-============-=============-============================================
> ii  host         20000331-9    utility for querying DNS servers
> If it matters I run a local name-server and do have a 6-to-4 tunnel.

That does not matter.  The protocol you use to query the nameservers
(IPv4 or IPv6) has no influence whatsoever on the results returned from
the queries.  Those results are only influenced by the queries being
made and the entries in the zone.

So, your "host" program asks only for A records.  Mine asks both A and
AAAA.  (and MX as well)
Your "aaaa" program (which I don't have) asks for AAAA records.

This is all not very relevant for the result in the webbrowser.
It depends on what queries the webbrowser makes, and what it does with
the results.

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