The answer is to regularly apply security patches using AWS Systems Manager Patch Manager, use security groups as a virtual firewall, and disable password-based SSH access in favor of key pairs. Security groups act as a stateful firewall at the instance level, controlling inbound and outbound traffic based on allow rules, while key-based authentication eliminates the risks of brute-force attacks associated with passwords. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your understanding of foundational EC2 security best practices, often appearing as a multi-select item where common traps include assuming the default VPC is secure—it actually allows inbound internet traffic by default—or thinking instance metadata is a safe place for secrets. Remember the mnemonic “P-S-K”: Patch, Security groups, Key pairs.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. 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.
Which THREE are AWS best practices for securing an Amazon EC2 instance? (Choose three.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use security groups to control inbound and outbound traffic.
The correct answers are A, C, and E. Option A is correct because security groups act as a virtual firewall. Option C is correct because disabling password-based SSH access in favor of key pairs is a security best practice. Option E is correct because AWS Systems Manager Patch Manager helps keep instances up to date. Option B is wrong because the default VPC allows inbound traffic from the internet by default; best practice is to create a custom VPC with appropriate rules. Option D is wrong because storing secrets in instance metadata is not secure; use AWS Secrets Manager or Parameter Store.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Store database credentials in instance metadata for easy retrieval.
Why it's wrong here
Instance metadata is not secure; use AWS Secrets Manager or Parameter Store.
✗
Launch instances in the default VPC for easier network configuration.
Why it's wrong here
The default VPC has permissive rules; it is better to create a custom VPC with controlled access.
✓
Use security groups to control inbound and outbound traffic.
Why this is correct
Security groups are the primary mechanism for controlling network traffic to EC2 instances.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✓
Disable password-based authentication and use SSH key pairs instead.
Why this is correct
Key pairs provide stronger authentication than passwords.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✓
Regularly apply security patches using AWS Systems Manager Patch Manager.
Why this is correct
Patch Manager automates the process of patching instances.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SCS-C02 NAT questions on configuration and troubleshooting.
Infrastructure Security — This question tests Infrastructure Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Use security groups to control inbound and outbound traffic. — The correct answers are A, C, and E. Option A is correct because security groups act as a virtual firewall. Option C is correct because disabling password-based SSH access in favor of key pairs is a security best practice. Option E is correct because AWS Systems Manager Patch Manager helps keep instances up to date. Option B is wrong because the default VPC allows inbound traffic from the internet by default; best practice is to create a custom VPC with appropriate rules. Option D is wrong because storing secrets in instance metadata is not secure; use AWS Secrets Manager or Parameter Store.
What should I do if I get this SCS-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SCS-C02 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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