Hi Guys
Need some help here as the Company now expects me to do a RCA (Root Cause Analysis) as to why one of our VM Hosts went into a disconnected state. I am no Fundy when it comes to analyzing logs, and VM LOGS are totally hieroglyphics to me. Here is what Happened:
Received an Alert that one of our VM Hosts went into a Disconnected (Isolated State) – Host was unreachable on the Network although all VM’s (Guests) was still Booted and Operational without Network loss. In vSphere client both Hosts were visible in the Cluster and the One host had a small red cross on it with light greyed out text saying disconnected. The Guests on that Host showed the same. When right clicking on the Host and selecting Connect brought up an Error Message saying the Host doesn't exist or could not be found. So I manually shutdown all the VM's with RDP and then Rebooted the Host. After the host was up I could connect it to the Cluster without problems and start up all the VM Guests on that HOST. So basically the Problem is solved but i need to know why and how this happened and provide concrete evidence 
Hope you guys can Help!! 