Citrix server cannot be found when connecting from remote location

A small organsation needed access to our Citrix servers. They had access to our LAN from a certain gateway put away on a deep dark spot in our network.
When they tried to connect to our servers, they would receive the “Server cannot be found” or similair messages but sometimes they would be able to connect!!!
Well..this was quite the puzzle which makes perfect sense now in retrospect. The DNS servers in that Office had no records from our environment. The admin in that office added a hostname from 1 of our Citrix Servers in their ICA Client and also in their hostfile. They forgot about loadbalancing!!!
1 out of 10 times they would be able to connect when the server which was added in their host file was chosen by Citrix Loadbalancing. The quickest fix was to add all our Citrix servers to the Windows host file of the client computer.