- A
Disable SSH and use AWS Systems Manager Session Manager to connect to instances.
Why wrong: Session Manager provides secure access but does not address the existing SSH rule; the question asks to restrict SSH.
- B
Create a network ACL with an inbound rule allowing SSH from 203.0.113.0/24 and deny all other traffic.
Why wrong: NACLs are stateless and would affect all traffic; this is more complex and less efficient.
- C
Modify the existing security group rule to change the source from 0.0.0.0/0 to 203.0.113.0/24.
Modifying the existing rule directly updates the source to the required CIDR, removing the open access.
- D
Create a new security group rule allowing SSH from 203.0.113.0/24 and keep the existing rule.
Why wrong: Keeping the existing 0.0.0.0/0 rule still allows all inbound SSH traffic.
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.
A company is using Amazon EC2 instances in a VPC with a security group that allows inbound SSH from 0.0.0.0/0. A security engineer needs to restrict SSH access to only the company's public IP range (203.0.113.0/24) while maintaining all other existing rules. What is the MOST efficient way to accomplish this?
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
Modify the existing security group rule to change the source from 0.0.0.0/0 to 203.0.113.0/24.
Option C is correct because modifying the existing security group rule's source from 0.0.0.0/0 to 203.0.113.0/24 directly restricts inbound SSH to the company's public IP range without affecting any other rules. Security groups are stateful and rule changes apply immediately, making this the most efficient approach as it requires only a single edit to the existing rule.
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.
- ✗
Disable SSH and use AWS Systems Manager Session Manager to connect to instances.
Why it's wrong here
Session Manager provides secure access but does not address the existing SSH rule; the question asks to restrict SSH.
- ✗
Create a network ACL with an inbound rule allowing SSH from 203.0.113.0/24 and deny all other traffic.
Why it's wrong here
NACLs are stateless and would affect all traffic; this is more complex and less efficient.
- ✓
Modify the existing security group rule to change the source from 0.0.0.0/0 to 203.0.113.0/24.
Why this is correct
Modifying the existing rule directly updates the source to the required CIDR, removing the open access.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a new security group rule allowing SSH from 203.0.113.0/24 and keep the existing rule.
Why it's wrong here
Keeping the existing 0.0.0.0/0 rule still allows all inbound SSH traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think adding a more specific allow rule overrides a broader allow rule, but security groups use an allow-list model where all rules are additive, so the original 0.0.0.0/0 rule must be removed or modified to actually restrict access.
Detailed technical explanation
How to think about this question
Security groups act as a virtual firewall at the instance level, and rules are evaluated collectively—any rule that matches allows traffic, so removing the overly permissive rule is essential. Under the hood, security group rules are implemented as stateful packet filtering in the AWS hypervisor, meaning that changes to rules take effect within seconds and do not require instance reboots. In a real-world scenario, failing to remove the old 0.0.0.0/0 rule would leave a security gap, as both rules would coexist and allow traffic from any source.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Infrastructure Security — study guide chapter
Learn the concepts, then practise the questions
- →
Infrastructure Security practice questions
Targeted practice on this topic area only
- →
All SCS-C02 questions
1,748 questions across all exam domains
- →
AWS Certified Security Specialty SCS-C02 study guide
Full concept coverage aligned to exam objectives
- →
SCS-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related SCS-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Threat Detection and Incident Response practice questions
Practise SCS-C02 questions linked to Threat Detection and Incident Response.
Security Logging and Monitoring practice questions
Practise SCS-C02 questions linked to Security Logging and Monitoring.
Identity and Access Management practice questions
Practise SCS-C02 questions linked to Identity and Access Management.
Management and Security Governance practice questions
Practise SCS-C02 questions linked to Management and Security Governance.
Infrastructure Security practice questions
Practise SCS-C02 questions linked to Infrastructure Security.
Data Protection practice questions
Practise SCS-C02 questions linked to Data Protection.
SCS-C02 fundamentals practice questions
Practise SCS-C02 questions linked to SCS-C02 fundamentals.
SCS-C02 scenario practice questions
Practise SCS-C02 questions linked to SCS-C02 scenario.
SCS-C02 troubleshooting practice questions
Practise SCS-C02 questions linked to SCS-C02 troubleshooting.
Practice this exam
Start a free SCS-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this SCS-C02 question test?
Infrastructure Security — This question tests Infrastructure Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the existing security group rule to change the source from 0.0.0.0/0 to 203.0.113.0/24. — Option C is correct because modifying the existing security group rule's source from 0.0.0.0/0 to 203.0.113.0/24 directly restricts inbound SSH to the company's public IP range without affecting any other rules. Security groups are stateful and rule changes apply immediately, making this the most efficient approach as it requires only a single edit to the existing rule.
What should I do if I get this SCS-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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More SCS-C02 practice questions
- A company uses AWS Organizations with multiple accounts. The security team wants to enforce that all Amazon S3 buckets a…
- A company is designing a multi-tier web application on AWS. The web tier must be accessible from the internet, but the a…
- A company is migrating a legacy application to AWS. The application requires two-way communication between the web serve…
- A security engineer is troubleshooting connectivity issues between an Amazon EC2 instance in a VPC and an on-premises se…
- A security engineer is reviewing the SQS queue policy shown in the exhibit. The queue is subscribed to an SNS topic in t…
- A company uses AWS Organizations with multiple accounts. The security team wants to ensure that all IAM users in the pro…
Last reviewed: Jul 4, 2026
This SCS-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 SCS-C02 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.