Failover Cluster VM can talk on the network but can’t respond…

This was one of those things when you make a mistake configuring something and then it doesn’t behave the way you’d expect it to.

When I setup a 3 Hyper-v VM’s one of the machines could not be reached from the network. All 3 machines were installed on a 2 node failover cluster. What was weird was the machine I couldn’t talk to (i.e.. I couldn’t ping or Remote desktop into) could ping machines on the network and receive responses. It also could get an IP address from a DHCP out on the network.

After failing miserably at troubleshooting the issue I installed a 4th VM to the same failover cluster. Everything worked. I went and installed a 5th machine and everything seemed to work.

I did some live migrations and fooled around with things. This morning I tried accessing a VM that could be communicated with last night. It started acting very similar to the machine that was “misbehaving” the day before.

It turns out I missed a small but VERY important step when configuring the VM. I forgot to “Enable spoofing of MAC addresses”.

In order to enable this the machine needs to be off. Once off, you can place a check mark into the selection box. Once done I rebooted the machine and it could now talk back and forth as one would normally expect.