You need to identify the minimum number of required public IP addresses for each Skype for Business Server 2015 component.
How many public IP addresses should you reserve for each component? To answer, select the appropriate number of public IP addresses for each component in the answer area.
Hot Area:
The minimum number of required public IP addresses for a SfB Edge server is 1.
“Your Edge Server can be configured to use a single IP address with distinct ports for each service, or it can use distinct IP addresses for each service, but use the same default port (which by default will be TCP 443).”
https://docs.microsoft.com/es-es/skypeforbusiness/plan-your-deployment/edge-server-deployments/edge-environmental-requirements