The subnet IP address allows the user to connect to NetScaler Gateway from an external host that resides on another subnet. When you add a subnet IP address, a corresponding route entry is made in the route table. Only one entry is made per subnet. The route entry corresponds to the first IP address added in the subnet.
Unlike the system IP address and the mapped IP address, it is not mandatory to specify the subnet IP address during initial configuration of NetScaler Gateway.
The mapped IP address and subnet IP addresses use ports 1024 through 64000.