Answer :
- Registration requests are proxied through the Citrix Cloud Connectors to the Citrix Cloud Delivery Controllers.
Explanation :
When using Citrix cloud solution, then we have Delivery Controllers in Citrix Cloud and Cloud Connectors in place of DDCs in Control layer, As VDAs are part of on-premises location, so they must register themselves to Cloud Connectors FQDN, which is then proxied to Cloud Delivery Controllers over outboud port 443.