Q. In a 3-node cluster, if 2 of the nodes cannot communicate with each other but can both communicate with the 3rd node what will happen?
A. Consider a scenario of three locations with each location having one node in a cluster. For some reason two of the locations lose connectivity with each other but can still both communicate with the 3rd site, which means only the node in the third location can communicate to both the other nodes. This is shown below.
The node in site B will not communicate on behalf of the nodes in sites A and C. This means quorum will not be maintained on all nodes, instead the node in either site A or in site C will lose quorum and its cluster service and any cluster dependent services would stop. The cluster would keep running on the remaining nodes.