CCSP Cloud Platform and Infrastructure Security Practice Question
This CCSP practice question tests your understanding of cloud platform and 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.
A multi-tier web application is deployed across two VPCs connected via VPC peering. The web tier in VPC A must communicate with the database tier in VPC B on port 3306. Security groups are used for instance-level security. Which security group configuration is MOST secure?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
In the database security group, add an inbound rule allowing TCP/3306 from the security group ID of the web servers.
The most secure approach is to allow inbound traffic to the database security group from the web server security group by referencing its ID (security group ID). This ensures that only instances in the web server security group can reach the database, regardless of IP changes. Option A is less secure because any instance in the CIDR range could connect. Option B is correct. Options C and D involve network ACLs or routing, which are not instance-level.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
In the database security group, add an inbound rule allowing TCP/3306 from the security group ID of the web servers.
Why this is correct
Security group referencing ensures only instances in the web security group can connect.
Configure a VPN connection between VPCs and use route tables to direct traffic.
Why it's wrong here
VPN adds complexity but does not replace the need for security group rules.
✗
In the network ACL for VPC B's subnet, add an inbound rule allowing TCP/3306 from VPC A CIDR.
Why it's wrong here
NACLs are stateless and subnet-level; not instance-level control.
✗
In the database security group, add an inbound rule allowing TCP/3306 from the VPC A CIDR.
Why it's wrong here
IP-based rules are less granular and do not adapt to dynamic IPs.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CCSP subnetting questions on CIDR, address ranges, and subnet selection.
Cloud Platform and Infrastructure Security — This question tests Cloud Platform and Infrastructure Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: In the database security group, add an inbound rule allowing TCP/3306 from the security group ID of the web servers. — The most secure approach is to allow inbound traffic to the database security group from the web server security group by referencing its ID (security group ID). This ensures that only instances in the web server security group can reach the database, regardless of IP changes. Option A is less secure because any instance in the CIDR range could connect. Option B is correct. Options C and D involve network ACLs or routing, which are not instance-level.
What should I do if I get this CCSP question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CCSP subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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