Returns whenever the given server_name exists.
This function returns if a server is registered against the kernel we have connected to.
On login process, among other data, it is received host location for every connected and registered server. This function allows to check if central server knows something about the given server_name.
If it is needed to know the current status for the given servers it would be better to use afdal_session_do_a_nop or afdal_session_do_a_nop_sync.
|server_name ||Name of the server to check for existence.|
- TRUE if the server exists, FALSE otherwise