Mailinglist Archive: opensuse-project (382 mails)

[Larry Finger <Larry.Finger@xxxxxxxxxxxx>]

On 05/07/2012 02:52 PM, Carlos E. R. wrote:
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> On 2012-05-07 20:39, Larry Finger wrote:
> > On 05/07/2012 11:49 AM, Carlos E. R. wrote:
>
> > The problem is that there is a brain-dead name server somewhere in
> > your chain that returns a record saying the "I support IPv6", but then
> > times out when a request is made. That is what happens, or at least
> > used to happen with my ISP's DNS service. By using Google, I bypass
> > them unless both of Google's servers are down.
>
> Sorry, I don't understand completely.
>
> Who has to support IPv6, the name resolver? My ISP? (it doesn't).

Posted below is the tcpdump output for my active network interface while I was 
doing nslookup on a non-existent domain:

 IP 192.168.1.103.40594 > google-public-dns-a.google.com.domain: 1880+ PTR? 
1.1.168.192.in-addr.arpa. (42)
 IP google-public-dns-a.google.com.domain > 192.168.1.103.40594: 1880 NXDomain 
0/0/0 (42)
 IP 192.168.1.103.44573 > google-public-dns-a.google.com.domain: 63970+ A? 
pop.gmail.com. (31)
 IP 192.168.1.103.44573 > google-public-dns-a.google.com.domain: 40939+ AAAA? 
pop.gmail.com. (31)
 IP 192.168.1.103.33341 > google-public-dns-a.google.com.domain: 3312+ A? 
www.xyz.comz. (30)

The above three lines are the critical ones. Since the name server returns that 
AAAA record, then my system is allowed to use IPv6 lookups. If no such record is 
returned, then only IPv4 is allowed.

Problems arise if the name server (whomever supplies it) returns that AAAA 
record but cannot resolve the IPv6 entity. Then the request times out causing 
all the problems you see in the Forums, etc.

Larry
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