The server list and downloads

The server list

Players find servers in the game’s server list, which a master server keeps. A server joins every list its masters setting names, the public one by default. It prints each list’s answer as it starts, and again as the answer changes:

master https://master.mynl.pl: listed as 203.0.113.7:28960

If the list cannot reach the server’s UDP port, the server says so instead: open the port.

Keep a test server off the list with masters=[], in the file or as --set 'masters=[]'.

The list shows each server’s name, map, game mode and players, and a padlock on a server with a password.

Downloads

A player joining downloads the mod’s files they lack: its maps, models, sounds, images and scripts. The server serves them itself, over TCP on the game’s port. A file two servers share is downloaded once, and a player keeps what they downloaded for the next time.

While a match plays, players’ games download the next match’s files in the background, so a map change takes seconds.

Mirrors

The download_urls setting lists up to 4 base URLs, such as a CDN in front of the server. Players try each in turn before the server itself. Each file is asked for by its hash, so a CDN that caches what the server sends needs nothing more.

The server reads download_urls once, as it starts.