The answer is that three steps are required: configuring the CodeBuild project to use the same VPC as the RDS instance, setting the security group to allow inbound traffic from CodeBuild, and ensuring outbound routes exist for CodeBuild to reach the RDS instance. This works because CodeBuild runs inside a VPC, so it must be placed in the same network as the private subnet RDS instance to communicate directly without traversing the internet. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of VPC connectivity for build services, often appearing as a trap where candidates mistakenly add a NAT gateway for internal traffic or try to place the database in a public subnet. Remember, a NAT gateway is only for outbound internet access, not for reaching resources within the same VPC. Memory tip: think "Same VPC, open SG, route out" — the security group must allow CodeBuild’s traffic in, and the subnet’s route table must have a local route to the RDS subnet.
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. 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 DevOps team is using AWS CodeBuild to run integration tests against a test database. The database is an Amazon RDS instance in a private subnet. The CodeBuild project is configured to run in a VPC. Which THREE steps are required to allow CodeBuild to access the RDS instance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Ensure the security group attached to the RDS instance allows inbound traffic from the CodeBuild security group.
Correct answers are A, B, and D. A: The CodeBuild project must have VPC configuration to place it in the same VPC. B: Security group must allow inbound traffic from CodeBuild. D: Outbound routes are needed to reach RDS. C is wrong because NATgateway is for internet access, not internal RDS. E is wrong because the database should be in a private subnet, and a public subnet is not needed.
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.
✗
Place the RDS instance in a public subnet with a public IP.
Why it's wrong here
RDS should be in private subnet for security.
✓
Ensure the security group attached to the RDS instance allows inbound traffic from the CodeBuild security group.
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 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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related DOP-C02 subnetting questions on CIDR, address ranges, and subnet selection.
SDLC Automation — This question tests SDLC Automation — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Ensure the security group attached to the RDS instance allows inbound traffic from the CodeBuild security group. — Correct answers are A, B, and D. A: The CodeBuild project must have VPC configuration to place it in the same VPC. B: Security group must allow inbound traffic from CodeBuild. D: Outbound routes are needed to reach RDS. C is wrong because NAT gateway is for internet access, not internal RDS. E is wrong because the database should be in a private subnet, and a public subnet is not needed.
What should I do if I get this DOP-C02 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 DOP-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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 DOP-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 DOP-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.