When creating a logical switch, you must specify which transport zone to create it against; whichever transport zone you select will define the scope of the logical switch across ESXi hosts. In the case of universal, there can only be a single universal transport zone; therefore, when selecting this transport zone in a logical switch definition, it is created for all vSphere cluster hosts that are participating in the Universal Transport Zone. See Chapter 2, Configuring VMware NSX Logical Switch Networks, to understand how a transport zone works.
In addition, which vSphere clusters to add to the Universal Transport Zone to, depends on where you want universal logical switches and universal distributed routers to exist. It ...
