ANS-C01 Network Security, Compliance and Governance Practice Question
A security engineer notices that a security group allows inbound SSH from 0.0.0.0/0. Which immediate action should be taken to reduce risk?
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 security group inbound rule to allow SSH only from the company's public IP range
The immediate action is to modify the security group inbound rule to restrict SSH access to only the company's public IP range (Option A). This reduces the attack surface by limiting exposure to trusted IPs. Option B is incorrect because adding a network ACL deny rule is not as effective since NACLs are stateless and the security group still allows inbound SSH from anywhere; also, NACLs operate at the subnet level and do not override security group rules for inbound traffic within the VPC. Option C is incorrect because moving instances to a different subnet is disruptive and does not address the current security group rule. Option D is incorrect because deleting the security group may affect running instances and is not the simplest immediate action.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Modify the security group inbound rule to allow SSH only from the company's public IP range
Why this is correct
Directly reduces attack surface.
- ✗
Add a network ACL deny rule for SSH from 0.0.0.0/0
Why it's wrong here
NACL is stateless and less precise than SG.
- ✗
Move the instances to a different subnet with a restrictive NACL
Why it's wrong here
Unnecessary and complex.
- ✗
Delete the security group and create a new one with the correct rules
Why it's wrong here
Could cause downtime if instances are using it.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 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 ANS-C01 exam.