Maintained by: NLnet Labs

[Unbound-users] Strange behavior with AAAA record

Teran McKinney
Sat Aug 2 13:55:56 CEST 2008


Sorry Florian, I accidentally sent this directly to just you and not to the ML.

----

Thanks for the quick response.

> Compare straces of both ping runs?

The slow `ping6 -c1 icadpytes.eleuther.net` strace dump:
http://go-beyond.org/sega01/misc/slowping6.txt

The working `ping6 -c1 icadpytes.go-beyond.org` strace dump:
http://go-beyond.org/sega01/misc/workingping6.txt

Things start to differ around line 150.

I thought that this was an interesting line:
connect(5, {sa_family=AF_INET6, sin6_port=htons(53),
inet_pton(AF_INET6, "::ffff:0.0.0.0", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28) = 0

There are 4 instances of "::ffff:0.0.0.0" in the
icadyptes.eleuther.net dump and none from one that works fine. I am
suprised  that it works when using Zoneedit's servers directly but not
when through Unbound.

> It looks like the problem is with the reverse lookup for
> 2001:470:3:e::1123:5813, which is broken.  Apparently, Unbound tries
> harder to get a resolution, which takes more time and slows ping6 down.

After investigating what you said a bit more, it is definitely the
reverse lookup. OpenDNS resolves the ip6.arpa record fine while
Unbound either takes 5 seconds or fails. Unbound works fine when there
is a PTR record in place however.

Should I file a bug report?

Thanks,
Teran (sega01)