We study the 'background traffic' resulting from tens of thousands of networked first person shooter (FPS) clients searching for servers on which to play. Networked, multiplayer games utilise the network in two distinct ways. Game play is typically built around a client-server communication model, and the resulting traffic patterns have been well studied to date. However, the discovery of available game servers is itself a client-server process. Operational game servers register themselves with well-known 'master servers', which are then queried by game clients looking for available servers. Game clients then probe the servers and retrieve information such as game type, number of other players, currently active map, and latency (ping time). We instrumented two active and public "Wolfenstein: Enemy Territory" servers over 20 weeks, developed a simple method to differentiate client probes from game-play traffic, and then characterized and contrasted the time-of-day, geographical distributions and traffic characteristics of both traffic types. We find that a significant amount of a server's traffic is probe traffic and the geographical origins are very different for both types of traffic. We propose techniques to improve server location and to decrease the amount of probe traffic.