What is a quorum? Describe how a quorum is used in failover cluster configuration.

What will be an ideal response?

In a quorum, a certain percentage of voting members must be present to conduct business.  This percentage is known as a quorum. In the failover cluster, a quorum must be present for the cluster to function.  Each host computer in the cluster that communicates with other host computers has a vote. If a disk witness or file share witness is available, it will get a vote. Microsoft defines four quorum modes:

Node Majority-Each available host computer that is in communication can vote. The cluster functions only when it has more than half the votes (a majority).

Node and Disk Majority-Each host computer plus a witness disk in cluster storage can vote, whenever they are available and in communication. The cluster functions only when more than half the votes are available.

Node and File Share Majority-Each host computer plus a file share witness created by the administrator can vote, whenever they are available and in communication. The cluster functions only when it has more than half the votes (a majority).

No Majority: Disk Only-The cluster has a quorum if one host computer is available and in communication with a specific disk in the cluster storage.