Q. Why shouldn't I share the management NIC on Hyper-V with virtual machines (VMs)?

A. The best practice for Hyper-V hosts is to have at least two NICs. One of the NICs should be used for the management of the host. This NIC should, for example, be used as the IP address you use to remote into the box or remotely execute Microsoft Management Console snap-ins.

The other NIC should be bound to a virtual switch. This one will be used by VMs and not exposed to the host.

It's possible to expose a virtual switch and make it visible on the Hyper-V host, allowing a single NIC to be used for both VMs and host management. This isn't recommended, however, because if VMs and the host share a NIC this way, the virtual switch controls the NIC. The virtual switch is part of the virtualization stack, so if there's a problem with your virtualization components you can't connect through the management switch, and you can't resolve your problem remotely.

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