disable IPV6?

[Daniel Roesen]

On Sat, Mar 06, 2004 at 03:10:42PM -0500, Randy Schrickel wrote:
> Here's the output from a dnslookup, ifconfig, and 'netstat -rn' on my
> box, with just IPV4 configured followed by the IPV6 results (as setup by
> the Fedora install):

Who is doing the DNS lookup?

> eth0      Link encap:Ethernet  HWaddr 00:01:03:C1:D1:BE
>            inet addr:192.168.0.100  Bcast:192.168.0.255  Mask:255.255.255.0
>            inet6 addr: fe80::201:3ff:fec1:d1be/64 Scope:Link

As you can see, IPv6 is enabled in the kernel. Otherwise you would
have no inet6 link-local addr.

Please show "ip addr show dev eth0" to make sure we have all the info.

> Kernel IP routing table

With "netstat -rn" you look up only IPv4 routes. Use "netstat -A inet6
-rn" or (much better): "ip -6 route".

> And here's the IPV6 version:
>    0.000000 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
> www.google.com

68.54.80.5 is being asked for AAAA RR but gives no reply. Retry:

>    5.000097 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
> www.google.com
>    5.010537   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
> CNAME www.g
> oogle.akadns.net

Now it answers with the CNAME. I'm seeing the same effect from here:

; <<>> DiG 9.2.3 <<>> www.google.com AAAA
[...]
;; ANSWER SECTION:
www.google.com.         3600    IN      CNAME   www.google.akadns.net.
[...]
;; Query time: 4727 msec

Why the resolver doesn't do an AAAA query for www.google.akadns.net.
consequently, is beyond me. Looks like a bug.

Instead of following the CNAME, it asks for an A RR:

>    5.010918 192.168.0.100 -> 68.54.80.5   DNS Standard query A 
> www.google.com
>    5.024892   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
> CNAME www.g
> oogle.akadns.net A 216.239.39.104 A 216.239.39.99 A 216.239.39.147

There, Akamai's DNS servers answer directly with A RRs for the CNAME.

>    5.025460 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
> 104.39.239.216.in-addr.arpa
>   10.025349 192.168.0.100 -> 68.54.80.5   DNS Standard query PTR 
> 104.39.239.216.in-addr.arpa
>   10.039552   68.54.80.5 -> 192.168.0.100 DNS Standard query response, 
> No such name

Interesting. Same "no response to first query" problem on a simple
PTR query. Nothing IPv6 specific here.

>   10.039963 192.168.0.100 -> 68.54.80.5   DNS Standard query AAAA 
> www.google.com
>   10.050470   68.54.80.5 -> 192.168.0.100 DNS Standard query response 
> CNAME www.g
> oogle.akadns.net

This one goes quickly... 68.54.80.5 has the answer cached.

> (that was from loading http://www.google.com Note the AAAA responses)

There are ne AAAA responses, but only a CNAME.

Actually, I see nothing going wrong IPv6-specific. There are two
pretty normal IPv4 DNS queries not being answered - one of them even
asking for a normal PTR RR, not even AAAA.

This will be probably tricky to debug properly.

Are those two different installations? Or how do you toggle "IPv6
enabled" (whatever that actually means - as both systems are obviously
IPv6 enabled per se).

IPv6 transport is not involved, but pls show "ip -6 route" anyway.

> If there's something else in the config that's needed, without shutting 
> off ipv6, that'd be fine. I just wanted to get my net connection working 
> the way it should, and turning ipv6 off did the trick. .Any other tests 
> or suggestions?

Currently, it looks like 68.54.80.5 or your network's NAT is misbehaving
somehow. What kind of device is doing the NAT?


Best regards,
Daniel