Empty server

So we were waiting for the last guy to play incursion. The leader of the group was farming DZ. And the thing is that it was completely empty. The other guy asked wtf is going on and the session leader doesnt said anything. Is it possible to enter the server and block other people or some other way.

I don't think that you can actually "close" a server, but you can close your NAT (aka set it to strict) so it's harder do connect with other clients (players)

I want to know if this is possible to farm DZ without pvp

Happened to me once with a friend of mine. We were playing in DZ and we both had open NAT. Suddenly we realized we were the only ones in DZ so we stayed in there for like 4 hours. LOL. Mind you, that was back in the beta though.