Which action is performed during the onboarding process when a WAN Edge router is connected to ZTP server ztp.viptela.com?

"WAN Edge Cloud Center" is not a standard component or destination in the Cisco SD-WAN ZTP process.

During the Zero Touch Provisioning (ZTP) process, when a WAN Edge router connects to the ZTP server, its immediate action is to retrieve the IP address or hostname of the vBond Orchestrator. The vBond Orchestrator acts as the first point of contact for the WAN Edge device to authenticate and then learn the addresses of the vManage NMS and vSmart controllers to establish control plane connections.

Establishing an IPsec tunnel to the vSmart Controller is a data plane connection, which happens much later in the onboarding process, after control plane tunnels are established and routes are exchanged.

Establishing a DTLS/TLS tunnel to the vSmart Controller is part of the control plane setup, which occurs after the WAN Edge has successfully contacted the vBond Orchestrator and received the vSmart controller information.