Which AWS services provide high availability across multiple Availability Zones by default?
(Choose two.)
Amazon EC2
Amazon Elastic Block Store (Amazon EBS)
Amazon Elastic File System (Amazon EFS)
Amazon Redshift
Amazon S3
Explanations:
Amazon EC2 instances are launched in a single Availability Zone by default, though multi-AZ setups can be configured manually.
Amazon EBS volumes are tied to a single Availability Zone, though snapshots can be copied across regions or AZs.
Amazon Elastic File System (EFS) is designed to provide high availability across multiple Availability Zones by default.
Amazon Redshift clusters are deployed in a single Availability Zone by default, though manual multi-AZ replication is possible.
Amazon S3 automatically replicates data across multiple Availability Zones within a region, providing high availability.
I think the answer is:
Amazon Elastic File System (Amazon EFS)