curious DNS behavior on a 7.0...

[Steve Bertrand]

Jonathan Horne wrote:
> reading the /etc/defaults/rc.conf, ipv6 appears disabled by default:
> 
> ### IPv6 options: ###
> ipv6_enable="NO"                # Set to YES to set up for IPv6.
> 
> however, right now "new" every website i browse is penalized with a 10-20 
> second delay before the page finally starts loading.  tcpdump is full of 
> these:
> 
> 20:38:57.915695 IP athena.dfwlp.com.59056 > castor.dfwlp.com.domain: 3505+ 
> AAAA? www.srh.noaa.gov. (34)
> 
> arent AAAA's ipv6 lookups?  as i mentioned in another thread, i cant get the 
> kernel to compile right now (thus eliminating the INET6 line), so im trying 
> to figure another way out to stop this behavior).

It's not required you remove IPv6 from the kernel in order to receive
proper DNS A record responses, and even if IPv6 name services take
precedence, it shouldn't cause such a delay (unless all of your
boxen/DNS servers point to the same forwarders that cause this issue).

I have several machines under 4.10 to 6.2, and at least two running 7.0
that are v6 enabled that don't have this issue.

I do run IPv6 in my network with a legitimate block, however, I do not
have any IPv6 name servers that contain any outside DNSv6 records.

That said, more particulars are needed to find out what is happening.

The most important thing to know in order to break this down is what
name server(s) are you using on this particular server to resolve names.

If you can post the output from the following whilst logged into one of
the problematic machines, it will likely help:

# cat /etc/resolv.conf

If your box is a DHCP client, I won't know what to look for in that
output. If by chance your box attains it's IP information via DHCP, then
the next following output (particularly the last few lines) will help:

# dig www.srh.noaa.gov

Your AAAA queries may or may not be detrimental to the time in which you
receive your DNS responses. I would personally lean toward the latter,
given the lack of information.

Don't go about recompiling the kernel without v6 support yet. It seems
DNS is timing out for you somewhere, so post the above requested info
and it can go from there.

Steve