[ntp:questions] Pool returns IPv6 address to IPv4 query
Majdi S. Abbas
msa at latt.net
Mon Nov 18 19:18:18 UTC 2013
On Mon, Nov 18, 2013 at 11:08:24AM -0800, A C wrote:
> One of the North America pool DNS round-robins (I think it was
> 2.north-america.pool.ntp.org) returned an IPv6 address to a system that
> made only an IPv4 request. So right now I have a server that ntpd
> thinks is broken because of the DNS confusion.
Are you sure it was an IPv4 request (i.e. qtype=A), rather than
a request for ANY, returning a mix of A and AAAA records?
> Note the last line in the billboard below. My machine does not have
> IPv6 enabled and DNS requests are passed on to my router which also does
> not have IPv6 enabled. For that matter, there is no IPv6 provided by my
> ISP and I don't have any IPv6 tunnels (e.g. Hurricane Electric).
It doesn't matter whether or not you have v6 enabled, you can
still query for and receive AAAA responses.
> I'll eventually get around to restarting ntpd and this will probably
> resolve itself but someone should check that the round-robin DNS queries
> are answered with the appropriate answer for the calling system.
> remote refid st t when poll reach delay offset
> o127.127.22.0 .PPS. 0 l 5 16 377 0.000 0.007
> -127.127.28.0 .GPSD. 4 l 4 16 377 0.000 108.331
> -188.8.131.52 184.108.40.206 2 u 269 512 377 37.361 -1.433
> +220.127.116.11 .CDMA. 1 u 42 512 377 103.045 3.111
> +18.104.22.168 .GPS. 1 u 450 512 377 94.050 4.697
> +22.214.171.124 126.96.36.199 2 u 458 512 377 112.834 1.710
> 2001:470:79::14 .INIT. 16 - - 1024 0 0.000 0.000
The fact that it's even trying means you didn't start ntpd with
-4, and the host has at least one IPv6 interface (this might be as
simple as v6 enabled on the loopback.)
So, either ensure that v6 is fully disabled on the host, or add
-4 to your ntpd startup parameters.
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