What query protocol does Battlefield 2 use?

Question

I have been searching for this all over the internet, this site claims that Battlefield 2 uses the GameSpy 2 protocol, I have tried this protocol, but it does not respond. I have also been working on the GameSpy 3 protocol, but that one is a lot harder.
I would like to know which one it uses so I know whether I am using the wrong protocol, or have an error in my code.

Answer 1

Battlefield 2 uses the Gamespy 3 protocol.

Source: GameQ library

From the GameQ config file:

[bf2]
name = "Battlefield 2"
port = 29900
prot = "gamespy3"
pack = "bf2"