正解:A
vbond-as-stun-server:
Enable Session Traversal Utilities for NAT (STUN) to allow the tunnel interface to discover its public IP address and port number when the vEdge router is located behind a NAT (on vEdge routers only).
When you configure this command, vEdge routers can exchange their public IP addresses and port numbers over private TLOCs.
With this configuration, the vEdge router uses the vBond orchestrator as a STUN server, so the router can determine its public IP address and public port number. (With this configuration, the router cannot learn the type of NAT that it is behind.) No overlay network control traffic is sent and no keys are exchanged over tunnel interface configured to the the vBond orchestrator as a STUN server. However, BFD does come up on the tunnel, and data traffic can be sent on it.