The answer is to check that the security group associated with the Glue job allows outbound traffic to the RDS database. A communications link failure in AWS Glue when connecting to a MySQL database almost always points to a network connectivity issue, not a credential or schema problem, because Glue jobs run in a Virtual Private Cloud (VPC) and must have explicit outbound rules to reach the RDS instance’s security group. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how Glue’s network configuration interacts with RDS security groups—a common trap is to jump to checking IAM permissions or table structures, but the error message itself is a clear signal to verify network paths first. Remember the mnemonic “Link First, Log Later”: when you see “link failure,” always check the security group link before diving into logs or permissions.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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 data engineer needs to troubleshoot a failed AWS Glue job that reads from an Amazon RDS for MySQL database. The error log shows 'Communications link failure'. Which step should the engineer take FIRST?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check that the security group associated with the Glue job allows outbound traffic to the RDS database.
Option B is correct because a 'Communications link failure' often indicates network connectivity issues; verifying that the Glue job's security group allows outbound traffic to the RDS database is the first troubleshooting step. Option A is wrong because the error is not about authentication. Option C is wrong because the issue is not about table structure. Option D is wrong because the error is not about permissions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Increase the job timeout and retry count.
Why it's wrong here
Does not address connectivity failure.
✓
Check that the security group associated with the Glue job allows outbound traffic to the RDS database.
Why this is correct
Network connectivity is the most common cause of this error.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Verify that the database username and password are correct in the Glue connection.
Why it's wrong here
Authentication would produce a different error.
✗
Confirm that the table schema in MySQL matches the Glue Data Catalog.
Why it's wrong here
Schema mismatch would cause a different error.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check that the security group associated with the Glue job allows outbound traffic to the RDS database. — Option B is correct because a 'Communications link failure' often indicates network connectivity issues; verifying that the Glue job's security group allows outbound traffic to the RDS database is the first troubleshooting step. Option A is wrong because the error is not about authentication. Option C is wrong because the issue is not about table structure. Option D is wrong because the error is not about permissions.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A data engineer notices that an AWS Glue ETL job is failing intermittently with the error 'Connection refused'. The job reads from Amazon RDS for MySQL and writes to Amazon S3. What is the MOST likely cause?
easy
A.The RDS instance has reached its maximum number of connections.
✓ B.The security group for the RDS instance is not allowing inbound traffic from the Glue job's subnet.
C.The Glue job is using too many DPUs and hitting resource limits.
D.The IAM role associated with the Glue job lacks permissions to write to the S3 bucket.
Why B: Option A is correct because the error indicates a network connectivity issue to the RDS database. Option B is incorrect because the error is not about permissions. Option C is incorrect because the error is about connection, not resource limits. Option D is incorrect because the error is not about job parallelism.
Last reviewed: Jun 20, 2026
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.
This DEA-C01 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 DEA-C01 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.