Correct Answer : Readers-writer
Explanation : Before version 2.2, this lock was implemented on a per-mongod basis. Since version 2.2, the lock has been implemented at the database level.
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.