This DVA-C02 practice question tests your understanding of deployment. 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 company uses AWS Elastic Beanstalk to deploy a Python web application. After a successful deployment, the environment's health turns 'Severe' and the application returns HTTP 502 errors. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The application's requirements.txt file is missing a required dependency.
Option A is correct because if the application's dependencies (e.g., Python packages) are not included or installed, the application fails to start, causing a 502 error. Option B is incorrect because an incorrectly configured load balancer would cause 503 or 504 errors. Option C is incorrect because exceeding instance storage would cause disk full errors, not 502. Option D is incorrect because RDS connection string misconfiguration would cause application errors but not necessarily 502; the web server would still respond.
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.
✗
The EC2 instances have insufficient storage for the deployment.
Why it's wrong here
Insufficient storage would cause disk write errors, but not necessarily a 502.
✓
The application's requirements.txt file is missing a required dependency.
Why this is correct
Missing dependency causes the application to fail to start, resulting in a 502 Bad Gateway from the proxy.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The load balancer's health check path is incorrectly configured.
Why it's wrong here
Incorrect health check path would cause the instance to be marked unhealthy, not 502 errors.
✗
The RDS database connection string is incorrect.
Why it's wrong here
Database connection issues would cause application-level errors, but the web server would still return a response, not a 502.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 DVA-C02 NAT questions on configuration and troubleshooting.
Deployment — This question tests Deployment — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The application's requirements.txt file is missing a required dependency. — Option A is correct because if the application's dependencies (e.g., Python packages) are not included or installed, the application fails to start, causing a 502 error. Option B is incorrect because an incorrectly configured load balancer would cause 503 or 504 errors. Option C is incorrect because exceeding instance storage would cause disk full errors, not 502. Option D is incorrect because RDS connection string misconfiguration would cause application errors but not necessarily 502; the web server would still respond.
What should I do if I get this DVA-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 DVA-C02 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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