A. ESXi servers, unlike most Windows servers, tend to have plenty of network connections, particularly if you haven't jumped to 10Gbps Ethernet connections yet. You might need adapters for your management connection, a few for production networking, some for storage, and maybe even an extra one for vMotion traffic.
That's a lot of adapters to keep straight when you're first setting up your ESXi host. The hard part is deciphering which physical adapter corresponds to which device name in ESXi's local System Customization GUI.
In the text-based GUI, click on Configure Management Network then Network Adapters. The resulting screen will display the list of adapters in the physical host, along with vmnic(x) device names, any assigned hardware labels, and MAC addresses. It can be difficult here to figure out which of the adapters you see represents the physical adapter you want to use for your management network.
There's a little trick you can use to find the right one quickly. This screen shows the connection status for each adapter. Adapters that show Connected are obviously plugged in. Simply head back to your datacenter and remove the Ethernet cables from the adapters you don't intend to use for your management connection. Return to the console and whichever vmnic(x) device still shows Connected is the one you're looking to configure.