Replacing Nagios with CloudWatch Agent for EC2 Monitoring
A company is migrating its on-premises applications to AWS and wants to maintain the same level of monitoring for its Linux-based EC2 instances. They currently use Nagios for monitoring. They want a managed AWS service that can monitor instance health, system metrics, and application logs. Which solution should they use?
Quick Answer
The correct solution is to install the Amazon CloudWatch agent on each EC2 instance to collect system metrics and logs, and send them to CloudWatch. This is because the CloudWatch unified agent replaces the functionality of Nagios by providing a single, managed service that captures detailed system-level metrics (like memory and disk usage) and application logs from Linux instances, which the basic EC2 metrics cannot provide. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of migrating from third-party monitoring tools to native AWS services, often appearing in questions that contrast CloudWatch with AWS Systems Manager Inventory, CloudTrail, or Config. A common trap is confusing CloudTrail (API auditing) or Config (compliance) with real-time monitoring, but remember: CloudWatch is for metrics and logs, while the others serve different purposes. Memory tip: think of CloudWatch as your "watch" for health and logs, not just a trail or config checker.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Install the Amazon CloudWatch agent on each EC2 instance to collect system metrics and logs, and send them to CloudWatch.
The Amazon CloudWatch agent (unified CloudWatch agent) can collect system metrics (CPU, memory, disk) and logs from EC2 instances and send them to CloudWatch, providing a managed monitoring solution similar to Nagios. Option B is incorrect because AWS CloudTrail is for auditing API calls, not for monitoring system metrics or logs. Option C is incorrect because AWS Systems Manager Inventory collects software inventory and configuration data, not real-time metrics or logs. Option D is incorrect because AWS Config tracks resource configuration changes for compliance, not for monitoring system health.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Install the Amazon CloudWatch agent on each EC2 instance to collect system metrics and logs, and send them to CloudWatch.
Why this is correct
The CloudWatch agent can collect both metrics and logs, replacing Nagios.
- ✗
Use AWS CloudTrail to monitor instance activity and capture log files.
Why it's wrong here
CloudTrail monitors API calls, not instance-level metrics.
- ✗
Use AWS Systems Manager Inventory to collect system configuration and log files.
Why it's wrong here
Inventory is for configuration data, not real-time monitoring.
- ✗
Use AWS Config to track instance configuration changes and trigger alerts.
Why it's wrong here
Config is for configuration compliance, not real-time health monitoring.
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Same concept, more angles
1 more way this is tested on DOP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A DevOps engineer is designing a monitoring solution for an application that runs on Amazon EC2 instances in an Auto Scaling group. The engineer needs to collect memory utilization metrics and visualize them in a dashboard. What should the engineer do?
medium- A.Create a custom CloudWatch metric namespace and publish memory data using the AWS CLI.
- ✓ B.Install the Amazon CloudWatch agent on the EC2 instances to collect memory metrics and publish them to CloudWatch.
- C.Enable detailed monitoring on the EC2 instances to collect memory metrics.
- D.Use AWS CloudTrail to capture memory utilization events from the EC2 instances.
Why B: Memory utilization is not collected by default by CloudWatch. The CloudWatch agent must be installed on EC2 instances to collect memory and disk metrics as custom metrics. Option A is incorrect because simply creating a custom namespace does not collect data; the agent is needed to publish data. Option C is incorrect because detailed monitoring only increases the frequency of default metrics (CPU, network, etc.) and does not include memory. Option D is incorrect because CloudTrail captures API calls, not system-level metrics like memory usage.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DOP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DOP-C02 exam.