The administrator should click thevmnic0interface on theESX-1 Host.

In aVMware Cloud Foundation (VCF)environment, theGENEVE (Generic Network Virtualization Encapsulation)protocol is the industry-standard tunnel format used by NSX to create an overlay network. This protocol allows Layer 2 traffic from virtual machines to be "tunneled" over a Layer 3 physical IP fabric, enabling workloads to communicate as if they were on the same segment even when separated by physical routers.

When VM-1 on ESX-1 sends an ICMP request to VM-2 on ESX-2, the packet starts as a standard Ethernet frame at the virtual machine'svnic1. At this stage, the packet contains no encapsulation. As the frame enters theVirtual Distributed Switch (VDS)and hits theTunnel End Point (TEP), the host's kernel performs the encapsulation process. The TEP adds a GENEVE header, a UDP header (port 6081), and an outer IP header.

Thevmnic0(physical NIC) on the source host (ESX-1) is the specific "egress" point where this transformation is complete. A packet capture taken at this physical interface will show the "Outer IP" address of the source TEP and destination TEP, with the original ICMP packet hidden inside the GENEVE payload. If the administrator were to click on the VM's vnic, they would only see standard ICMP. By selecting thevmnic0, the administrator captures the traffic as it is placed onto the physical wire, which is the verified location to troubleshoot MTU issues, encapsulation errors, or physical fabric connectivity in a VCF environment.