- A
AWS, because they own and operate all EC2 infrastructure
Why wrong: AWS is responsible for the underlying hardware, hypervisor, and physical security of EC2. However, once an EC2 instance is launched, the guest operating system is the customer's responsibility.
- B
The customer, because OS patching is in the customer's area of responsibility for IaaS services
For EC2 (IaaS), the customer is responsible for the guest OS including patching, security configuration, and updates. AWS manages the hypervisor and physical infrastructure below the OS.
- C
Both AWS and the customer equally share this responsibility
Why wrong: Responsibility is not equally shared — the dividing line is clear. AWS owns the hypervisor and below; the customer owns the guest OS and above. OS patching is entirely the customer's responsibility.
- D
A third-party managed service provider designated by AWS
Why wrong: AWS does not designate third parties for OS patching. The responsibility falls clearly on the customer unless they use a managed service like RDS that abstracts OS management.
Quick Answer
The answer is the customer, because under the AWS Shared Responsibility Model, patching the operating system on EC2 instances falls squarely on the customer’s side of the line for Infrastructure as a Service (IaaS). AWS secures the physical host, the hypervisor, and the network fabric, but once you launch an EC2 instance, you assume full control—and full responsibility—for the guest OS, including applying security updates and patches. On the AWS Certified Cloud Practitioner CLF-C02 exam, this concept tests your understanding of how responsibility shifts with service type: for IaaS like EC2, you manage everything above the hypervisor, while for managed services like RDS or Lambda, AWS handles the OS. A common trap is assuming AWS patches everything on EC2, but the key distinction is that you chose the AMI and manage the instance’s lifecycle. Remember the mnemonic: “IaaS means I patch the OS; PaaS means AWS patches the OS.”
CLF-C02 Security and Compliance Practice Question
This CLF-C02 practice question tests your understanding of security and compliance. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 web application on Amazon EC2 instances. Under the AWS Shared Responsibility Model, who is responsible for patching the operating system on the EC2 instances?
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
The customer, because OS patching is in the customer's area of responsibility for IaaS services
Under the AWS Shared Responsibility Model, for Infrastructure as a Service (IaaS) like EC2, the customer is responsible for managing the guest operating system, including patching and security updates. AWS is responsible for the physical infrastructure and the hypervisor layer, but not for the OS running inside the EC2 instance. Therefore, option B is correct.
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.
- ✗
AWS, because they own and operate all EC2 infrastructure
Why it's wrong here
AWS is responsible for the underlying hardware, hypervisor, and physical security of EC2. However, once an EC2 instance is launched, the guest operating system is the customer's responsibility.
- ✓
The customer, because OS patching is in the customer's area of responsibility for IaaS services
Why this is correct
For EC2 (IaaS), the customer is responsible for the guest OS including patching, security configuration, and updates. AWS manages the hypervisor and physical infrastructure below the OS.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Both AWS and the customer equally share this responsibility
Why it's wrong here
Responsibility is not equally shared — the dividing line is clear. AWS owns the hypervisor and below; the customer owns the guest OS and above. OS patching is entirely the customer's responsibility.
- ✗
A third-party managed service provider designated by AWS
Why it's wrong here
AWS does not designate third parties for OS patching. The responsibility falls clearly on the customer unless they use a managed service like RDS that abstracts OS management.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume AWS handles all patching for EC2 because it is a managed service, but the Shared Responsibility Model clearly assigns guest OS patching to the customer for IaaS services like EC2.
Detailed technical explanation
How to think about this question
The AWS Shared Responsibility Model delineates that AWS secures the 'Security OF the Cloud' (physical data centers, hardware, hypervisor), while the customer secures 'Security IN the Cloud' (guest OS, applications, data). For EC2, this means customers must apply OS patches, configure firewalls (e.g., security groups), and manage IAM roles. A real-world scenario: if a critical vulnerability like CVE-2023-44487 is announced, the customer must patch their EC2 instances; AWS will patch the underlying hypervisor but not the guest OS.
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.
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Security and Compliance — study guide chapter
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Security and Compliance — This question tests Security and Compliance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The customer, because OS patching is in the customer's area of responsibility for IaaS services — Under the AWS Shared Responsibility Model, for Infrastructure as a Service (IaaS) like EC2, the customer is responsible for managing the guest operating system, including patching and security updates. AWS is responsible for the physical infrastructure and the hypervisor layer, but not for the OS running inside the EC2 instance. Therefore, option B is correct.
What should I do if I get this CLF-C02 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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Last reviewed: Jun 11, 2026
This CLF-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 CLF-C02 exam.
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