The answer is to configure CodeBuild to use a VPC with a NAT gateway. This solution directly resolves the random build failures caused by the 'Could not download dependencies' error, as a NAT gateway provides a stable, managed internet path for your CodeBuild environment to pull Docker images from Amazon ECR and download external dependencies. Without a VPC configuration, builds rely on the default public network, which can be inconsistent or blocked by security policies. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how to integrate CodeBuild with VPC networking to ensure reliable internet access for private builds—a common trap is to increase the build timeout or instance size, which only masks the symptom. Remember the key insight: for consistent outbound internet access from a private subnet, always pair a NAT gateway with your build project. Memory tip: "NAT for net access, not more time or size."
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 startup is using AWS CodeBuild to build and test their application. The build process takes about 10 minutes. Recently, they noticed that some builds are failing randomly with the error 'Could not download dependencies'. The build environment uses a custom Docker image stored in Amazon ECR. The team suspects that the issue is due to network connectivity problems when pulling the Docker image or dependencies from the internet. They want to ensure reliable and faster builds. Which solution should they implement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure CodeBuild to use a VPC with a NAT gateway
To improve reliability and speed, use an Amazon ECR repository in the same region and configure CodeBuild to use a VPC with a NATgateway for internet access, or use a VPC endpoint for ECR. The best approach is to use a VPC with a NAT gateway to provide consistent internet access. Option A is correct. Option B (increase build timeout) does not fix the root cause. Option C (use a larger instance) may not resolve network issues. Option D (use a public Docker Hub) may still have network issues and is not controlled.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Switch to using a public Docker image from Docker Hub
Why it's wrong here
Public Docker Hub may also have network issues and is less controlled
✗
Increase the build timeout in CodeBuild project settings
Why it's wrong here
Timeout increase does not solve network failures
✗
Use a larger compute type for the CodeBuild project
Why it's wrong here
More CPU/memory does not fix network connectivity
✓
Configure CodeBuild to use a VPC with a NAT gateway
Why this is correct
VPC with NATgateway provides reliable internet access for pulling images and dependencies
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DOP-C02 NAT questions on configuration and troubleshooting.
SDLC Automation — This question tests SDLC Automation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Configure CodeBuild to use a VPC with a NAT gateway — To improve reliability and speed, use an Amazon ECR repository in the same region and configure CodeBuild to use a VPC with a NAT gateway for internet access, or use a VPC endpoint for ECR. The best approach is to use a VPC with a NAT gateway to provide consistent internet access. Option A is correct. Option B (increase build timeout) does not fix the root cause. Option C (use a larger instance) may not resolve network issues. Option D (use a public Docker Hub) may still have network issues and is not controlled.
What should I do if I get this DOP-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DOP-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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