For the exam you will need to understand the ports in use by the Virtual Desktop Agents. The VDA is installed on the master image and, as such, is on all machines in the catalog. Port 80 is used to talk with the Desktop Delivery Controllers and ICA to the clients. ICA is normally on port 1494 but is, by default, tunneled though port 2598 (Session Reliability). This allows for temporary network disruptions such as those associated with mobile networks.
Session reliability is controlled though group policy so could be disabled if required. This would be normal if we needed Citrix Branch Repeater to manage ICA traffic.