One of the prerequisites is to have IQService ‘on the same domain as the SharePoint Server’. Does it mean that the SharePoint Server, the IQService host and the virtual appliance should be in the same network?
Can the three be on different physical servers, or do they also have to be on the same server as the VA?
Yes, the SharePoint Server and the IQService should be part of same network.
They can be installed on different physical Servers as long as they can communicate with each other across the network. The SharePoint server connector is carried out via IQService only, so you need to keep both on same network or domain. The VA can be placed anywhere on the network as it should have proper connectivity with the IQService listening port.