Distribute the nodes of an Elasticache cluster across different AZs

Question

The Elasticache cluster contains 10 shards, as can be seen from the list below. The two nodes in each cluster are all members of the same REplicationGroup. Multi-AZ is disabled and Auto-failover is enabled.

 "CacheClusterId","PreferredAvailabilityZone","ReplicationGroupId"
 'abcde1234-0001-001', 'us-east-1a', 'abcde1234'
 'abcde1234-0002-001', 'us-east-1a', 'abcde1234'
 'abcde1234-0001-002', 'us-east-1b', 'abcde1234'
 'abcde1234-0002-002', 'us-east-1b', 'abcde1234'
 'abcde1234-0003-001', 'us-east-1b', 'abcde1234'
 'abcde1234-0003-002', 'us-east-1a', 'abcde1234'
 'abcde1234-0004-001', 'us-east-1b', 'abcde1234'
 'abcde1234-0004-002', 'us-east-1a', 'abcde1234'
 'abcde1234-0005-001', 'us-east-1a', 'abcde1234'
 'abcde1234-0005-002', 'us-east-1b', 'abcde1234'
 'abcde1234-0006-001', 'us-east-1b', 'abcde1234'
 'abcde1234-0006-002', 'us-east-1a', 'abcde1234'
 'abcde1234-0007-001', 'us-east-1a', 'abcde1234'
 'abcde1234-0007-002', 'us-east-1b', 'abcde1234'
 'abcde1234-0008-001', 'us-east-1b', 'abcde1234'
 'abcde1234-0008-002', 'us-east-1a', 'abcde1234'
 'abcde1234-0009-001', 'us-east-1b', 'abcde1234'
 'abcde1234-0009-002', 'us-east-1a', 'abcde1234'
 'abcde1234-0010-001', 'us-east-1a', 'abcde1234'
 'abcde1234-0010-002', 'us-east-1b', 'abcde1234'

Here, only us-east-1a and us-east-1a are used. us-east-1c and us-east-1d are not used. How to evenly distribute the nodes to the four AZs? (with the cli or console)

Does Multi-AZ needs to be enabled?