Comment 41 for bug 417757
Revision history for this message
| Jeroen Massar (massar) wrote Re: [karmic regression] all network apps / browsers suffer from multi-second delays by default due to IPv6 DNS lookups | #41 |
@ Zack Evans #40
I quickly looked at the Privoxy 3.0.12 IPv6-patch included in Debian (and probably the same thing in Ubuntu) and it seems that it is quite incomplete and has quite a number of broken assumptions. One of the primary brokeness is actually documented in the patch with: /* TODO: Allow multihomed hostnames */ indeed, that also means that if a host has multiple A and/or AAAA records, it will only try to use the first one, which might actually be an IPv6 address (which is generally preferred). As an example www.google.com has generally 4 IPv4 IP addresses (A records) and as that Privoxy patch only supports 1 address per hostname, it will only use one of those. If that single address is then IPv6, it will try IPv6.
If your IPv6 connectivity is then broken (which might also be the problem for other hosts) then of course it will take quite some time for that to timeout....
I would say: file a bug report against privoxy as clearly the patch that is included can various websites which have multiple addresses to only have the use of one address. and of course only IPv6 or IPv4 is then supported by it... in other words: BROKEN.
With the above in mind, people who have problems with "IPv6" should perform two tests:
- ip ro sho |grep default
^---- if you have a default route somewhere then of course it will be used, thus check where it goes and if that makes sense for you.
- for i in `cat /etc/resolv.conf | grep ^nameserver | cut -f2 -d' '`; do dig @$i www.microsoft.com AAAA; done
^-- if this has huge latency then your DNS resolver (or one above it) is broken. Do test this also with different hostnames then just www.microsoft.com, try especially hostnames that you didn't check in a while as they might be cached somewhere.