Hi! After I upgraded to 9.04, DNS lookups have been horribly slow. I suppose this is only a problem when IPv6 is enabled. I believe that this can be fixed without disabling IPv6, because Windows does it much better, both on Firefox and Internet Explorer. Let's say I am trying to go to <domain> with a web browser.
Firefox and IE on Windows Vista and 7:
(if <domain> does not contain a dot, it searches the "local" search domain, <domain>.getinternet.no in my case)
1. Send A (v4) query for <domain> and wait for reply.
2. If it got some reply, send AAAA query for <domain>.
3. Choose whether to use IPv6 or IPv4 domain according to some algorithm.
Firefox on Ubuntu
If an AAAA record is found, then an A request is sent, but the AAAA is generally chosen.
1. Send AAAA (v6) query for <domain> and wait for reply
2. If it is not found, send AAAA (v6) for <domain>.getinternet.no (*)
3. If it is not found, send A query for <domain> (which usually works)
(*) getinternet.no is what appears in the search line in my
/etc/resolv.conf, this will depend on your ISP.
The problem is that the AAAA request seems to upset my router (a D-Link) at some times, so the lookups takes a very long time. The search for the subdomain of getinternet.no is never in the cache, so it needs to do an extra , unncessary lookup.
Is there any way to suppress the subdomain lookup, and possibly also make Firefox send an A lookup first? The ideal way would be to send the A and the AAAA query in parallel, but I suppose that would require a major rewrite.