Is ubuntu trying to resolve localhost to an ipv6 address?

[Gavin McCullagh]

Hi,

On Tue, 20 Apr 2010, john wrote:

> I am troubleshooting some network issues. Running wireshark and
> watching traffic I notice I have many messages like this:
> 
> DNS Standard query AAAA localhost.vanguard.vashonsd.org
> DNS Standard query response, no such name

This is normal enough.  The process is usually:

1. The resolver will attempt to find an IPv6 AAAA address for the name.  
2. If an IPv6 address is returned, see is there a route to it.
3. Attempt to connect over IPv6.

If any of the above fail, do the same for IPv4.  So a DNS query for AAAA
records is pretty normal.  If you don't have IPv6 set up, step 2 will fail,
even where a AAAA address is returned.

> /etc/hosts looks like
> 
> 127.0.0.1	localhost
> 127.0.1.1	vbuntu vbuntu.vanguard.vashonsd.org
> 10.114.5.50	paul.vanguard.vashonsd.org	paul
> 
> my /etc/nsswitch.conf file has this entry
> 
> hosts            files dns wins

So when /etc/hosts is checked for a AAAA record, that fails and a DNS
request is made.

> What exactly is going on here? It looks like the server is trying to query
> a IP6 FQDN for localhost.

Yup.  This is pretty normal.

Gavin