[squid-users] confused over ipv6 failing on ipv4-only network

[Amos Jeffries]

On 6/01/2016 7:29 p.m., Jason Haar wrote:
> On 06/01/16 17:39, Amos Jeffries wrote:
>> On 6/01/2016 5:04 p.m., Jason Haar wrote:
>>> Hi there
>>>
>>> Weird - several times in the past couple of months I have found I cannot
>>> get to http://wiki.squid-cache.org/ - I get the error below from my
>>> squid-3.5.11 server which does not have a Global ipv6 address (it has a
>>> Local ipv6/fe80: on the Ethernet card - but nothing else). Google.com
>>> (which is fully ipv6 capable) works fine - so far only
>>> wiki.squid-cache.org has shown up this way to me (ie I don't see this
>>> error message.
>>>
>>> On the squid server, "dig a" shows valid ipv4 addresses and "dig aaaa"
>>> shows the ipv6 address - but why is squid even trying to connect over
>>> ipv6 If doesn't have an ipv6 address?
>>>
>>> Could this be a case of the "A" record failing to return fast enough,
>>> forcing squid to only try ipv6 - which then leads to the error message
>>> referring to the ipv6 address?
>> Squid waits for both A and AAAA before continuing after DNS lookup. The
>> only way to get only IPv6 results is for your DNS server to produce no A
>> results at all. Timeout _could_ do that, but the default is 30 sec so
>> unlikely.
> 
> I think that must be the case, because when I saw the problem this
> morning, I immediately ssh'ed into the squid server and nslookup showed
> it was resolving the name to it's A record just fine (by then) - and
> telnet-ing to the IPv4 address was fine too. So it must have either
> timed out on the A lookups (but not the AAAA records), or the DNS server
> didn't return A records at all? I don't think there's a way to query
> squid to see what it's current DNS cache is? That would definitively
> answer that question

The cache manager "ipcache" report contains a listing of the DNS cache:
 squidclient mgr:ipcache


> 
> 
>> The Squid wiki is dual-stacked with IPv4 addresses. Sice you have
>> v4-only network the thing to do is find out why the IPv4 are not
>> working for your Squid. 
> 
> Well yeah  - but I frankly don't see this on any other website (like
> google.com) - just wiki.squid-cache.org - so I think there's something
> going on between those DNS servers and my squid server sitting on a
> SPARK NZ network

Hmm. Wiki is in Italy IIRC so almost worst case RTT for us. Though I've
not seen such issues from my Orcon POP.

Amos