AWS Certified Solutions Architect – Associate — All Questions
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A company wants its RDS database to automatically fail over to a standby in another Availability Zone with minimal downtime during an AZ outage. Which feature provides this?
- a.A read replica in the same AZ
- b.Manual snapshots taken hourly
- c.RDS Multi-AZ deployment with a synchronous standby✓
- d.Storing backups in S3 Glacier
RDS Multi-AZ maintains a synchronous standby replica in a second Availability Zone and automatically fails over to it if the primary fails, providing high availability. Read replicas are for scaling reads and are asynchronous, not automatic failover. Snapshots and Glacier backups aid recovery but do not deliver automatic failover.
To decouple a fluctuating order-processing workload so that a spike in orders does not overwhelm the processing tier, which service should sit between the producers and consumers?
- a.Amazon SQS queue that the processing tier polls✓
- b.A single large EC2 instance for all processing
- c.Amazon Route 53 latency routing
- d.An EBS volume shared across instances
Amazon SQS buffers messages, letting the processing tier consume at its own pace and absorbing spikes without dropping work, which improves resilience and enables independent scaling. A single instance is a bottleneck and single point of failure. Route 53 handles DNS routing and EBS is block storage, neither of which decouples the tiers.
A stateless web tier runs on EC2 across two Availability Zones. The architecture must automatically replace unhealthy instances and adjust capacity to demand. Which combination achieves this?
- a.A single EC2 instance with a static Elastic IP
- b.Manually launching instances when alarms fire
- c.An Application Load Balancer only, with fixed instances
- d.An Auto Scaling group spanning both AZs behind an Application Load Balancer with health checks✓
An Auto Scaling group distributed across multiple AZs launches replacement instances when health checks fail and scales in or out based on demand, while the ALB spreads traffic across healthy targets. A single instance or manual intervention cannot self-heal. An ALB alone does not replace failed instances or change capacity.
A shared file system must be mounted concurrently by hundreds of Linux EC2 instances across multiple Availability Zones, and it must scale storage automatically. Which service fits best?
- a.Amazon EBS volume attached to each instance
- b.Amazon EFS mounted from all instances✓
- c.Instance store volumes
- d.A single S3 bucket mounted as a block device
Amazon EFS is a fully managed, elastic NFS file system that many instances across multiple AZs can mount simultaneously, scaling capacity automatically. A standard EBS volume attaches to one instance in one AZ, and instance store is ephemeral. S3 is object storage and is not a POSIX file system for concurrent block mounts.
A company needs a relational database that provides MySQL compatibility, replicates six copies of data across three Availability Zones, and offers fast automated failover. Which service best meets this?
- a.Amazon Aurora✓
- b.A self-managed MySQL cluster on a single EC2 instance
- c.Amazon DynamoDB
- d.Amazon Redshift
Aurora is MySQL- and PostgreSQL-compatible and stores six copies of data across three AZs, providing high durability and fast failover to a replica. A single EC2 MySQL instance is a single point of failure. DynamoDB is a NoSQL key-value store and Redshift is a data warehouse, neither of which is a MySQL-compatible relational OLTP database.
A global application must route users to a healthy Region and fail over automatically to a secondary Region if the primary becomes unavailable. Which approach provides this DNS-level resilience?
- a.A single Elastic IP in one Region
- b.An Application Load Balancer spanning Regions
- c.Amazon Route 53 with health checks and failover routing policy✓
- d.A NAT gateway in each subnet
Route 53 failover routing uses health checks to detect an unhealthy primary endpoint and automatically returns the secondary Region's record, enabling cross-Region DNS failover. An ALB cannot span multiple Regions. Elastic IPs and NAT gateways are single-Region constructs and do not provide global failover.