The default Phex GWC is old, if possible, the developers should either replace it or remove it. The GWC should probably just be upgraded to a different GWC software.

Anyways, I wrote my own GWC code that handles much better and is written in PHP 5. Beacon Cache II ( SourceForge.net: Beacon Cache ( Multi-Network Web Cache ): Beacon Cache ( Multi-Network Web Cache ) ) should be used instead of the much outdated GWCs. Don't worry, beacon cache handles spec 1 and spec 2 requests and updates, so nothing needs to change in request handling.

Beacon Cache II has options to weed out updates from banned IP addresses, block 'fake' GnucDNA clients, block Vendor Codes, and block User Agents, as well as operate between flat-file and MySQL.

Example (And working) Beacon Cache II GWCs Running:

Beacon Cache II 0.2.3.1
Beacon Cache II 0.2.3.1
Beacon Cache II 0.2.3.1
Beacon Cache II 0.1.19.1
http://gwc.dyndns.info:28960/gwc.php