I've had this doubt on my mind for some time: Are game instances in the same universe linked to the same server?
What I mean is, Imagine a game with two levels(1,2) which currently holds two active servers (A,B). When teleporting from games in a universe (levels in this example) is it possible for players from server A to end up teleporting in an instance of the second level where they could met with players from server B? or will always players from server A end up in level instances of the linked server A where they can only meet with players from server A?
It Depends
For example
Imagine a game where there are 2 levels (l,m)
Now, If a player has joined level l, and another player has joined the level m, You should see that the only relation between these two different servers, two different levels are only related with one thing, which is the game itself.
Which means, there is no relation between the two players in different servers of two different levels of a game.
Another case
If the developer chooses to control, for exam, if you ever played Apoc, you find that you are able to join similar groups of people, that is, your friends. Or, 2 opponents are teleported to the same place in the game universe etc. In this case, the developer has to make a reference between both the levels and set paths between the two levels.
So, the conclusion is that you are able to control the flow of players between servers & levels. It depends on how you code the game.