The correct answer is that the host '10.0.1.50' is not listed in the pg_hba.conf file. This is the most likely cause because PostgreSQL authentication in Amazon RDS relies on host-based authentication rules defined in pg_hba.conf, which controls which IP addresses or CIDR ranges are allowed to connect with specific users and databases. When the password is confirmed correct, a failure from a specific host almost always points to a missing or misconfigured entry for that host in the pg_hba.conf rules, which are managed through a custom DB parameter group in RDS. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how RDS abstracts on-premises PostgreSQL configuration—specifically that you cannot directly edit pg_hba.conf but must modify the `rds.force_ssl` parameter or add entries via the `rds.pg_hba.conf` parameter group setting. A common trap is assuming the issue is a password mismatch or SSL enforcement when the error explicitly shows the host IP; always check the pg_hba.conf rules first. Memory tip: "Hosts in HBA, or stay away"—if the host isn't listed, authentication is blocked regardless of credentials.
DBS-C01 Management and Operations Practice Question
This DBS-C01 practice question tests your understanding of management and operations. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
Exhibit
Refer to the exhibit.
Exhibit: CloudWatch Logs snippet
```
2023-01-15T12:00:00Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
2023-01-15T12:00:01Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
2023-01-15T12:00:02Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
```
A database administrator sees the above error logs in CloudWatch for an Amazon RDS for PostgreSQL DB instance. The application team confirms that the password for 'app_user' is correct. What is the most likely cause of the authentication failures?
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.
Refer to the exhibit.
Exhibit: CloudWatch Logs snippet
```
2023-01-15T12:00:00Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
2023-01-15T12:00:01Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
2023-01-15T12:00:02Z [ERROR] [Client] Authentication failed for user 'app_user' from host '10.0.1.50' using password
```
A
The password has expired for 'app_user'.
Why wrong: Password expiry would cause a different error message.
B
The user 'app_user' does not have the LOGIN privilege.
Why wrong: A LOGIN privilege issue would result in a different error.
C
The host '10.0.1.50' is not listed in the pg_hba.conf file.
RDS for PostgreSQL uses pg_hba.conf entries to allow client connections; if the host is not allowed, authentication fails despite correct password.
D
The database is in read-only mode.
Why wrong: Read-only mode does not affect authentication.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The host '10.0.1.50' is not listed in the pg_hba.conf file.
The errors show authentication failures from a specific host. If the password is correct, the most likely cause is that the host is not allowed by the pg_hba.conf configuration. RDS for PostgreSQL uses DB parameter groups to control pg_hba.conf rules; the rds.force_ssl parameter or the pg_hba.conf entries may not include that host.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 password has expired for 'app_user'.
Why it's wrong here
Password expiry would cause a different error message.
✗
The user 'app_user' does not have the LOGIN privilege.
Why it's wrong here
A LOGIN privilege issue would result in a different error.
✓
The host '10.0.1.50' is not listed in the pg_hba.conf file.
Why this is correct
RDS for PostgreSQL uses pg_hba.conf entries to allow client connections; if the host is not allowed, authentication fails despite correct password.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
The database is in read-only mode.
Why it's wrong here
Read-only mode does not affect authentication.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DBS-C01 questions on access control and AAA configuration.
Management and Operations — This question tests Management and Operations — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The host '10.0.1.50' is not listed in the pg_hba.conf file. — The errors show authentication failures from a specific host. If the password is correct, the most likely cause is that the host is not allowed by the pg_hba.conf configuration. RDS for PostgreSQL uses DB parameter groups to control pg_hba.conf rules; the rds.force_ssl parameter or the pg_hba.conf entries may not include that host.
What should I do if I get this DBS-C01 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related DBS-C01 questions on access control and AAA configuration.
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?
Authentication checks who the user is.
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 DBS-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 DBS-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.