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Distributed computing is a collection of machines to work as a coherent group. Machines run their own operations and communicate with each other over network. The idea behind replication is to keep multiple copies of data on physically isolated machines so that the failure in one does not impact the others. Consensus based replication functions like a parliament. Multiple machines elect a leader, agree on a value through consensus. They stop functioning when majority of machines fail. This is similar to the way parliaments works, starts functioning when. majority prevails.