This SCS-C02 practice question tests your understanding of infrastructure security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
SSH access is allowed from a large internal CIDR block (10.0.0.0/8) which could expose the instance to unnecessary internal threats.
Option C is correct because allowing SSH (TCP port 22) from the entire 10.0.0.0/8 CIDR block is overly permissive. This range encompasses all RFC 1918 private addresses in the 10.x.x.x space, which could include many internal subnets, VPNs, or peered VPCs that do not require administrative access. Unnecessarily broad internal access increases the attack surface and violates the principle of least privilege.
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.
✗
The template does not associate the security group with the instance, so the instance has no security group.
Why it's wrong here
The template does associate via Ref.
✗
HTTP access is allowed from all IP addresses (0.0.0.0/0) which is a security risk.
Why it's wrong here
HTTP to 0.0.0.0/0 is typical for public web servers; not necessarily a risk.
✓
SSH access is allowed from a large internal CIDR block (10.0.0.0/8) which could expose the instance to unnecessary internal threats.
Why this is correct
10.0.0.0/8 is a large range; should be more restrictive.
Related concept
Read the scenario before looking for a memorised answer.
✗
The template uses SecurityGroups property instead of SecurityGroupIds, which is deprecated.
Why it's wrong here
SecurityGroups is still valid for EC2-Classic, but in VPC, SecurityGroupIds is recommended but not a security risk.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on the obvious risk of opening SSH to 0.0.0.0/0, but the question tests whether they recognize that an overly broad internal CIDR (10.0.0.0/8) is also a significant security risk, especially when SSH is involved.
Detailed technical explanation
How to think about this question
The 10.0.0.0/8 CIDR block covers over 16 million IP addresses, often used in large enterprise or multi-account AWS environments. If an attacker compromises any resource within that range (e.g., a compromised EC2 instance or a misconfigured VPN), they could attempt SSH brute-force attacks against the instance. AWS Security Groups are stateful, so allowing inbound SSH from 10.0.0.0/8 also implicitly allows outbound return traffic, but does not restrict which internal sources can initiate connections.
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.
Visual reference
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 — 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: SSH access is allowed from a large internal CIDR block (10.0.0.0/8) which could expose the instance to unnecessary internal threats. — Option C is correct because allowing SSH (TCP port 22) from the entire 10.0.0.0/8 CIDR block is overly permissive. This range encompasses all RFC 1918 private addresses in the 10.x.x.x space, which could include many internal subnets, VPNs, or peered VPCs that do not require administrative access. Unnecessarily broad internal access increases the attack surface and violates the principle of least privilege.
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 →
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.
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.