The first step to diagnose EC2 connectivity issues behind an ALB is to review CloudWatch metrics for the instance and the ALB target group. This is correct because intermittent connectivity problems are often rooted in transient performance or health-check failures, and CloudWatch metrics like TargetResponseTime, RequestCount, and HealthyHostCount provide immediate, objective visibility into latency spikes, request drops, or the instance being marked unhealthy—without making unnecessary changes to the infrastructure. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this question tests your ability to apply the AWS Well-Architected Framework’s principle of observability, where data-driven diagnosis precedes any troubleshooting action. A common trap is jumping to check security groups or NACLs first, but those cause hard failures, not intermittent issues. Memory tip: think “Metrics before moves”—always check CloudWatch metrics before touching any configuration.
PAS-C01 Operations and Maintenance Practice Question
This PAS-C01 practice question tests your understanding of operations and maintenance. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company runs a production EC2 instance that experiences intermittent connectivity issues. The instance is part of an Auto Scaling group behind an Application Load Balancer. Which step should be taken FIRST to diagnose the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Review CloudWatch metrics for the instance and the ALB target group
Reviewing CloudWatch metrics for the instance and the ALB target group is the correct first step because it provides immediate visibility into the root cause of intermittent connectivity issues. Metrics such as TargetResponseTime, RequestCount, and HealthyHostCount can reveal whether the problem is due to high latency, request failures, or the instance being marked unhealthy by the ALB health checks. This data-driven approach avoids unnecessary changes and aligns with the AWS Well-Architected Framework's principle of observability.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Modify the security group to allow all traffic temporarily
Why it's wrong here
Opening security groups blindly reduces security and does not diagnose the issue.
✓
Review CloudWatch metrics for the instance and the ALB target group
Why this is correct
CloudWatch metrics provide baseline data for troubleshooting connectivity issues.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Terminate the instance and let Auto Scaling launch a new one
Why it's wrong here
Terminating without investigation does not identify root cause.
✗
Attach an additional Elastic Network Interface (ENI) to the instance
Why it's wrong here
Adding an ENI does not diagnose intermittent connectivity and may complicate the setup.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to reactive actions like terminating the instance or modifying security groups, failing to recognize that CloudWatch metrics provide the non-invasive, systematic starting point for diagnosing intermittent issues in an Auto Scaling group behind an ALB.
Detailed technical explanation
How to think about this question
CloudWatch metrics for an ALB target group include `HealthyHostCount` and `UnhealthyHostCount`, which are derived from the ALB's health check probes (e.g., HTTP 200 responses). Intermittent connectivity often manifests as periodic spikes in `TargetResponseTime` or `HTTP 5xx` errors, which can be correlated with instance-level metrics like `CPUUtilization` or `NetworkIn` to pinpoint resource exhaustion or network throttling. Additionally, the ALB's access logs (if enabled) provide per-request details such as `target_status_code` and `request_processing_time`, which can isolate whether the issue is at the load balancer or the instance level.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Operations and Maintenance — This question tests Operations and Maintenance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Review CloudWatch metrics for the instance and the ALB target group — Reviewing CloudWatch metrics for the instance and the ALB target group is the correct first step because it provides immediate visibility into the root cause of intermittent connectivity issues. Metrics such as TargetResponseTime, RequestCount, and HealthyHostCount can reveal whether the problem is due to high latency, request failures, or the instance being marked unhealthy by the ALB health checks. This data-driven approach avoids unnecessary changes and aligns with the AWS Well-Architected Framework's principle of observability.
What should I do if I get this PAS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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