As you may notice, the 3rd server is a World at War - HardCore Team DeathMatch server.
The server is compatible only with CoD:WaW beta clients for now.
When Treyarch will release the full version of WaW, the server will also become Full. Note: WaW Beta is free to play, all you need to do is signup in: www.callofduty.com and most likely they will issue a Beta CD Key and a client download mirror.
Another note: Full version of WaW will be only available to play if you buy it. No more cracked servers in WaW.