A company uses memory-optimized Amazon EC2 instances behind a Network Load Balancer (NLB) to run an application. The company launched the EC2 instances from an AWS-provided Red Hat Enterprise Linux…

Question

Options

• AConfigure detailed monitoring for the EC2 instances. Configure the Amazon CloudWatch agent
• BConfigure detailed monitoring for the EC2 instances. Use the mem_used_percent metric that the
• CConfigure basic monitoring for the EC2 instances. Configure the Amazon CloudWatch agent on
• DConfigure basic monitoring for the EC2 instances. Use the standard mem_used_percent metric

• A
  3% (1)
• B
  7% (2)
• C
  72% (21)
• D
  17% (5)

Explanation

EC2 does not publish RAM utilization as a native CloudWatch metric by default. Memory metrics such as mem_used_percent are typically collected by the CloudWatch Agent, which runs on the instance and publishes custom metrics to CloudWatch. Because the requirement is RAM utilization at 5-minute intervals, the CloudWatch Agent can be configured to emit metrics at that cadence (or faster). "Detailed monitoring" for EC2 mainly affects EC2-provided metrics (like CPU) by changing the period from 5 minutes (basic) to 1 minute (detailed). It does not magically provide memory utilization. Therefore, the key requirement is installing/configuring the CloudWatch Agent and ensuring it has permissions to publish metrics (via an IAM role attached to the instance / instance Option C correctly combines: (1) basic monitoring (fine for the ask), (2) CloudWatch Agent to publish mem_used_percent, (3) IAM role permissions to allow publishing, and (4) Auto Scaling policy that scales based on the memory metric. Option B incorrectly implies detailed monitoring provides mem_used_percent (it does not). Option D assumes a "standard" memory metric exists without the agent, which is not correct. Option A standard memory measurements for scaling policies, and also omits the IAM role requirement needed for publishing custom metrics. Thus, C is the AWS-correct path for memory-based scaling using CloudWatch custom metrics.

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