Say the webserver is called foo, on the domain company.local.  No ipv6 is 
enabled in the network.  A network trace tells me that when the HTTP request 
comes in, the webserver sends out a DNS request for "AAAA".  
Nothing replies, and after 5 seconds it times out and carries on doing what it 
was doing.

Why would it be doing a DNS lookup for the IPv6 address of its own hostname?  
And more urgently, how can I stop it? 

-----Original Message-----
From: Tom Lloyd 
Sent: 24 May 2012 16:26
To: 'Matijn Woudt'
Subject: RE: [PHP-DB] Mysterious 5 second delay on sybase_connect()

I'm getting increasingly suspicious that DNS is to blame.  If I was to do 
something like:

$conn = sybase_connect( "\SQLMAIN", $user, $pass )

Would that trigger a lookup of some variety?

-----Original Message-----
From: Matijn Woudt []
Sent: 24 May 2012 13:00
To: Tom Lloyd
Subject: Re: [PHP-DB] Mysterious 5 second delay on sybase_connect()

On Thu, May 24, 2012 at 10:51 AM, Tom Lloyd <> wrote:
> Hi there.  I'm working on a PHP-driven project on Debian Squeeze that 
> connects to an instance of Microsoft SQL Server on Windows Server 2008.
> I'm using the sybase extensions to PHP.
> Since I rebooted the webserver on the weekend, both the
> sybase_connect() and sybase_pconnect() commands will sometimes take 
> exactly 5 seconds to execute.  It seems to be random whether they do 
> this or not.  I can't think of anything that could have been changed 
> by the reboot, unless a package was updated but its associated process never 
> got restarted...
> Does anyone know what might cause this behaviour?
> Cheers,
> Tom Lloyd

It most likely has nothing to do with PHP, but is rather a routing issue. 5 
seconds is the default connection time out for TCP/IP, so it probably makes 
sense that the connection is failing at a lower level.

- Matijn

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