Memcache localhost connection oddity

Question

When I try to connect to memcache using this code:

$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");

The call dies with the "Could not connect" error, but if I use localhost's IP:

$memcache = new Memcache; 
$memcache->connect('127.0.0.1', 11211) or die ("Could not connect");

It works! So what's my problem? Well, this new computer is the only development environment I've setup that's been sensitive to that difference. I'm not about to go changing the settings on any code for what seems to be a computer specific issue, but I can't figure out what could be causing this behaviour.

I'm running XP, memcached 1.2.4, and wampserver 2. I've checked the hosts file; it does have an entry for localhost, and the dns cache has been flushed... Any ideas?

Answer 1

Running "ping localhost", as Conspicuous Compiler suggested, revealed that localhost was resolving to ::1 rather than 127.0.0.1. This is the correct behaviour for a network using IPv6, but it was this that was confusing memcached. As I didn't require IPv6 at all, I uninstalled it;

Right-click on a Network Connection > Properties > Highlight "Microsoft TCP/IP version 6" > Uninstall

All good again!

Please note; it may be that you can solve the issue less destructively by mapping ::1 to localhost as an entry in your hosts file. I didn't try it...