AWS Certified SysOps Administrator – Associate (legacy) — Question 659

A company manages more than 1,000 Amazon EC2 instances running Amazon Linux 2 in multiple VPCs. A SysOps administrator must change the statically configured DNS server IP address on all the EC2 instances.
Which solution will require the LEAST amount of effort?

Answer options

• A. Develop an AWS Lambda function to update the corporate DNS IP address on all the EC2 instances.
• B. Run a shell script to update the corporate DNS IP address on each EC2 instance.
• C. Update the Amazon Machine Images (AMIs) of the EC2 instances to configure the updated corporate DNS IP address.
• D. Use the AWS Systems Manager Run Command to update the corporate DNS IP address on all the EC2 instances.

Correct answer: D

Explanation

AWS Systems Manager Run Command allows administrators to securely and remotely manage the configuration of large fleets of EC2 instances simultaneously, making it the most efficient solution. Creating custom Lambda functions or manually executing scripts on over 1,000 instances would introduce significant operational overhead and complexity. Rebuilding and redeploying AMIs for running instances is highly disruptive and unnecessary for a simple DNS configuration update.