The answer is a firewall blocking the database port. This is the most likely cause because the error indicates a network-level connectivity failure, such as a connection timeout, which occurs when the firewall prevents the TCP handshake between the application and the database server, even though the server name, credentials, and database service are all correctly configured. On the CISA exam, this scenario tests your understanding of network security controls and common deployment pitfalls; the trap is that candidates often blame misconfigured credentials or a stopped database service first, but a firewall rule silently dropping traffic on the standard port (e.g., TCP 1433 for SQL Server) is the classic culprit. A useful memory tip is to think of the three Cs: Credentials, Configuration, and Connectivity—when the first two are fine, always check the firewall for the Connectivity block.
CISA Practice Question: Information Systems Acquisition, Development and Implementation
This CISA practice question tests your understanding of information systems acquisition, development and implementation. 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.
Exhibit
Refer to the exhibit.
```
[ERROR] Deployment failed at step 3 of 5: Unable to connect to database 'DB_PROD'. Connection string: 'Server=prod-db.finance.contoso.com;Database=Finance;User Id=app_user;Password=*****;'
[WARN] Retry attempt 1: same error.
```
During a system deployment, the above error occurs. 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.
Refer to the exhibit.
```
[ERROR] Deployment failed at step 3 of 5: Unable to connect to database 'DB_PROD'. Connection string: 'Server=prod-db.finance.contoso.com;Database=Finance;User Id=app_user;Password=*****;'
[WARN] Retry attempt 1: same error.
```
A
Incorrect server name in connection string
Why wrong: The server name appears valid and resolves; a misconfigured network is more suspect.
B
Invalid password
Why wrong: An invalid password would typically result in an authentication error, not a connection timeout.
C
Database service not running on the server
Why wrong: If the service is not running, the error would be more specific, such as 'target machine actively refused it'.
D
Firewall blocking the database port
A firewall may be blocking the default SQL Server port (1433), preventing the connection.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Firewall blocking the database port
The error message (not shown but implied from context) typically indicates a network-level connectivity failure, such as 'cannot connect to server' or 'connection timed out'. A firewall blocking the database port (e.g., TCP 1433 for SQL Server, 3306 for MySQL, 1521 for Oracle) is the most likely cause because it prevents the application from establishing a TCP handshake with the database server, even if the server name, password, and database service are all correct.
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.
✗
Incorrect server name in connection string
Why it's wrong here
The server name appears valid and resolves; a misconfigured network is more suspect.
✗
Invalid password
Why it's wrong here
An invalid password would typically result in an authentication error, not a connection timeout.
✗
Database service not running on the server
Why it's wrong here
If the service is not running, the error would be more specific, such as 'target machine actively refused it'.
✓
Firewall blocking the database port
Why this is correct
A firewall may be blocking the default SQL Server port (1433), preventing the connection.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse a 'connection refused' error (service not running) with a 'timeout' error (firewall block), but CISA expects you to recognize that a firewall block produces no response, leading to a timeout, whereas a stopped service produces an immediate RST.
Detailed technical explanation
How to think about this question
When a firewall blocks a port, the client's TCP SYN packet is silently dropped, causing the client to retransmit and eventually time out (typically after 21 seconds on Windows with default settings). This contrasts with a 'connection refused' error (TCP RST), which occurs when the server actively rejects the connection because no service is listening on that port. In enterprise environments, database ports are often restricted by network ACLs or host-based firewalls like iptables or Windows Firewall, and the error message 'cannot connect to server' or 'timeout expired' is a classic indicator of such a block.
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.
TExam Day Tips
→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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Firewall blocking the database port — The error message (not shown but implied from context) typically indicates a network-level connectivity failure, such as 'cannot connect to server' or 'connection timed out'. A firewall blocking the database port (e.g., TCP 1433 for SQL Server, 3306 for MySQL, 1521 for Oracle) is the most likely cause because it prevents the application from establishing a TCP handshake with the database server, even if the server name, password, and database service are all correct.
What should I do if I get this CISA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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