Correct Answer : All of the above
Explanation : In MongoDB, write operations, e.g. db.collection.update(), db.collection.findAndModify(), db.collection.remove(), are atomic on the level of a single document.
Correct Answer : sh.disableBalancing()
Explanation : sh.disableBalancing() does not affect balancing of other collections in a sharded cluster.
Correct Answer : sh.getBalancerHost()
Explanation : sh.enableSharding() enables sharding on a specific database.
Correct Answer : sh.getBalancerState()
Explanation : sh.getBalancerState() returns true when the balancer is enabled and false if the balancer is disabled.