In standard IW4x, a master server acts as a directory. Clients query the master, receive a list of active game servers (IP:Port), and populate the browser. Any operator could host a master server.
Exclusive servers no longer rely on the master list. They use Discord as a "lobby." iw4x server list exclusive
The standard IW4x browser is functional but noisy. Here is why veteran players seek out exclusive lists: In standard IW4x, a master server acts as a directory
While IW4x has evolved, several hardcore communities maintain exclusivity. Do not expect to find these on the default list: In standard IW4x