CV0-004 Security Practice Question
A cloud administrator needs to ensure that a set of AWS EC2 instances can only be accessed via SSH from the corporate office IP range 203.0.113.0/24. Which configuration should the administrator implement?
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
✓
Create a security group with an inbound rule allowing TCP port 22 from 203.0.113.0/24
A security group acts as a stateful virtual firewall for EC2 instances. By specifying the source IP range 203.0.113.0/24 on the inbound SSH rule, only traffic from that range is allowed. Security groups are stateful, so return traffic is automatically permitted.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a security group with an inbound rule allowing TCP port 22 from 203.0.113.0/24
Why this is correct
Security groups are stateful and can restrict inbound SSH to the specific IP range.
- ✗
Deploy a VPN and require all SSH traffic to go through it
Why it's wrong here
A VPN is not necessary; a security group can directly restrict access.
- ✗
Configure a network ACL with an inbound allow rule for TCP port 22 from 203.0.113.0/24
Why it's wrong here
Network ACLs are stateless, requiring explicit inbound and outbound rules for all traffic, including the return SSH responses. While they filter by IP and port, their subnet-level operation means they apply to *all* instances within a subnet, not individual ones. This option is tempting because it filters by IP and port, but it is primarily used for broad, coarse-grained security at the subnet boundary, such as blocking an entire IP range from accessing any resources within a subnet.
- ✗
Use AWS WAF to block SSH traffic except from 203.0.113.0/24
Why it's wrong here
WAF operates at the application layer (HTTP/HTTPS) and does not filter SSH.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.