The answer is to configure the service as a systemd unit with Restart=on-failure. This is the most operationally efficient approach because systemd, the default init system on Amazon Linux 2, natively handles process supervision; the Restart=on-failure directive automatically restarts the service whenever it crashes with a non-zero exit code or is killed by a signal, eliminating the need for external scripts, cron jobs, or CloudWatch alarms. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this question tests your understanding of native OS-level resilience versus over-engineered solutions—a common trap is choosing a more complex answer like a Lambda function or a custom health-check script. Remember that for EC2 instances, the simplest, most reliable method is always to leverage the init system already running on the OS. Memory tip: think "systemd saves you from scripting"—if the service fails, systemd has your back with just one directive.
PAS-C01 Operations and Maintenance Practice Question
This PAS-C01 practice question tests your understanding of operations and maintenance. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 DevOps engineer needs to automatically restart a specific service on an EC2 instance whenever the service crashes. The instance is running Amazon Linux 2. Which approach is the MOST operationally efficient?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the service as a systemd unit with Restart=on-failure
Option C is correct because systemd, the default init system on Amazon Linux 2, provides a built-in `Restart=` directive that can be set to `on-failure`. This instructs systemd to automatically restart the service unit when it exits with a non-zero exit code or is terminated by a signal, without requiring any external monitoring or additional infrastructure. This is the most operationally efficient approach as it leverages the native service manager functionality with zero external dependencies.
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.
✗
Set up a CloudWatch alarm that triggers an SSM Run Command to restart the service
Why it's wrong here
This adds extra components and latency compared to a simple systemd configuration.
✗
Write a cron job that checks the service status every minute and restarts it if needed
Why it's wrong here
Cron adds polling overhead and is not as responsive as systemd.
✓
Configure the service as a systemd unit with Restart=on-failure
Why this is correct
systemd is the native init system and handles restarts efficiently.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use an AWS Lambda function that polls the service status and calls the EC2 reboot API
Why it's wrong here
Lambda is not designed for this low-level system management and adds complexity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often over-engineer the solution by choosing external AWS services (CloudWatch, Lambda) or traditional cron-based polling, overlooking the fact that the operating system's native service manager (systemd) already provides a simple, built-in mechanism for automatic service restart.
Detailed technical explanation
How to think about this question
Under the hood, systemd uses cgroups to track the main PID of a service and monitors its exit status via `waitid()` system calls. The `Restart=on-failure` directive triggers a restart when the process exits with a non-zero code, is killed by a signal (e.g., SIGKILL, SIGSEGV), or when an operation times out, but not for clean exits (exit code 0). In a real-world scenario, this is critical for high-availability services like Nginx or custom applications where you want immediate recovery without the overhead of external monitoring tools.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: Configure the service as a systemd unit with Restart=on-failure — Option C is correct because systemd, the default init system on Amazon Linux 2, provides a built-in `Restart=` directive that can be set to `on-failure`. This instructs systemd to automatically restart the service unit when it exits with a non-zero exit code or is terminated by a signal, without requiring any external monitoring or additional infrastructure. This is the most operationally efficient approach as it leverages the native service manager functionality with zero external dependencies.
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.
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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