AWS Certified SysOps Administrator – Associate (legacy) — Question 805

A user has launched five instances and have registered them with an ELB. How can the user add the sixth EC2 instance to the ELB?

Answer options

• A. The user must stop the ELB and add the sixth instance.
• B. The user can add the sixth instance on the fly through API, CLI or the AWS Management Con-sole.
• C. The user can add the instance and change the ELB config file.
• D. The ELB can only have a maximum of five instances.

Correct answer: B

Explanation

AWS Elastic Load Balancing (ELB) supports dynamic scaling, allowing users to register or deregister EC2 instances on the fly without any service interruption. This registration can be performed seamlessly via the AWS Management Console, AWS CLI, or AWS APIs. There is no need to stop the load balancer or modify local configuration files, and an ELB can scale to support many more than five instances.