AWS Certified Solutions Architect High Availability and Scalability 2 — Questions and Answers
Question 1: An application uses an Application Load Balancer with EC2 instances in two Availability Zones. After a recent deployment, one AZ becomes unhealthy. What does the ALB do automatically?
- Terminates all instances in the unhealthy AZ
- Routes all traffic to the healthy AZ while the unhealthy AZ recovers (Correct answer)
- Stops accepting new connections entirely
- Sends an SNS notification and waits for manual intervention
Correct answer: Routes all traffic to the healthy AZ while the unhealthy AZ recovers
ALB automatically detects unhealthy targets via health checks and routes traffic only to healthy targets across remaining AZs.
Question 2: A company wants to scale EC2 instances based on the number of messages in an SQS queue. Which Auto Scaling policy type is most appropriate?
- Simple scaling policy
- Step scaling policy
- Target tracking scaling policy using a custom CloudWatch metric (Correct answer)
- Scheduled scaling policy
Correct answer: Target tracking scaling policy using a custom CloudWatch metric
Target tracking scaling with a custom CloudWatch metric (e.g., ApproximateNumberOfMessages per instance) is ideal for SQS-driven scaling.
Question 3: Which RDS feature automatically promotes a standby replica to primary when the primary instance fails, minimizing downtime?
- Read Replica promotion
- Multi-AZ failover (Correct answer)
- RDS Proxy connection pooling
- Aurora Global Database failover
Correct answer: Multi-AZ failover
RDS Multi-AZ maintains a synchronous standby that is automatically promoted during a primary failure, typically within 60-120 seconds.
Question 4: A web application needs to handle sudden traffic spikes that last only a few minutes. Which EC2 Auto Scaling feature best handles this without over-provisioning?
- Predictive scaling
- Scheduled scaling
- Dynamic scaling with step scaling policies
- Warm pools (Correct answer)
Correct answer: Warm pools
Warm pools keep pre-initialized EC2 instances ready to launch quickly, reducing launch latency during sudden short spikes.
Question 5: An Elastic Load Balancer must distribute traffic to EC2 instances across three AZs, but one AZ has significantly fewer instances. Which feature ensures even distribution?
- Sticky sessions
- Cross-zone load balancing (Correct answer)
- Connection draining
- Path-based routing
Correct answer: Cross-zone load balancing
Cross-zone load balancing distributes requests evenly across all registered instances in all enabled AZs, regardless of instance count per AZ.
Question 6: A company uses Aurora MySQL and wants zero-downtime read scaling. They already have 3 read replicas. What is the maximum number of Aurora read replicas supported per cluster?
- 5
- 10
- 15 (Correct answer)
- 25
Correct answer: 15
Amazon Aurora supports up to 15 read replicas per cluster, enabling significant read scaling beyond what standard RDS supports.
Question 7: Which Route 53 routing policy distributes traffic based on the geographic location of the DNS query origin, helping reduce latency for global users?
- Weighted routing
- Latency-based routing (Correct answer)
- Geolocation routing
- Failover routing
Correct answer: Latency-based routing
Latency-based routing directs users to the AWS region that provides the lowest network latency, not just the geographically closest region.
AWS Certified Solutions Architect High Availability and Scalability 2
An application uses an Application Load Balancer with EC2 instances in two Availability Zones.
After a recent deployment, one AZ becomes unhealthy.
What does the ALB do automatically?