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Elastic Load Balancing

5 minutes 5 Questions

Elastic Load Balancing (ELB) is an AWS service that automatically distributes incoming application traffic across multiple Amazon EC2 instances to balance the workload. This helps ensure high availability and fault tolerance by distributing the traffic to healthy instances and routing it away from …

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AWS Certified Solutions Architect - Elastic Load Balancing Example Questions

Test your knowledge of Elastic Load Balancing

Question 1

An e-commerce website is experiencing a sudden increase in traffic during a promotional event. The developers need to maintain high availability for the application while ensuring the system uses resources efficiently. Which Elastic Load Balancer configuration meets these requirements?

Correct Answer: Use an Application Load Balancer with an Auto Scaling group

Using an Application Load Balancer alongside an Auto Scaling group ensures that traffic is distributed evenly among EC2 instances and provides automatic scaling of resources to handle traffic. Classic Load Balancer and Network Load Balancer would not efficiently distribute the traffic, and neither EC2 Instance Recovery nor RDS Multi-AZ address scalability needs. AWS Global Accelerator improves user experience but does not address resource scaling.

Question 2

An application running on EC2 instances behind an Application Load Balancer (ALB) now uses WebSocket (ws/wss) for real-time communication. WebSocket connections are disconnecting after a short period. What change should you make on the ALB to ensure stable WebSocket connections?

Correct Answer: Increase the ALB idle timeout to accommodate long-lived WebSocket connections.

Application Load Balancers natively support WebSocket (ws/wss) over HTTP/HTTPS; there is no toggle to enable the WebSocket protocol. WebSocket connections are long-lived and can be closed by the ALB if they are idle longer than the default 60-second idle timeout. Increasing the ALB’s idle timeout ensures the load balancer does not terminate upgraded WebSocket connections prematurely, allowing them to remain open as required by the application.

Question 3

A company has an application running on EC2 instances behind a Network Load Balancer (NLB). The instances need to be updated, but the company wants to avoid downtime. What is the recommended approach?

Correct Answer: Update the instances by performing rolling updates using an Auto Scaling group

Performing rolling updates using an Auto Scaling group ensures that instances are updated sequentially with the desired number of instances remaining available during the update process. This avoids downtime. The other options may cause downtime or do not properly address the issue.

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