Over-estimation of game server RTT during FPS server discovery

Online multiplayer first person shooter (FPS) games typically utilise a client-server architecture, and use a two-step process to find available game servers. Clients query a well-known master server for a list of registered game servers, then probe each listed game server in turn. This process emits thousands of probe packets over a short period of time. A client estimates the round trip time (RTT) to each server based on the time between emitting a probe and receiving a reply. Using examples from CounterStrike:Source this report illustrates how an excessive probe emission rate can artificially inflate the RTT to individual game servers.