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XK0-006 Practice Question: Based on the exhibit, what is the most likely…
Exhibit
Refer to the exhibit. ``` $ cat /var/log/containers/web.log | grep "ERROR" | head -5 [2024-03-21 10:15:23] ERROR: Connection refused to database at 10.0.0.1:3306 [2024-03-21 10:15:24] ERROR: Connection refused to database at 10.0.0.1:3306 [2024-03-21 10:15:25] ERROR: Connection refused to database at 10.0.0.1:3306 [2024-03-21 10:15:26] ERROR: Connection refused to database at 10.0.0.1:3306 [2024-03-21 10:15:27] ERROR: Connection refused to database at 10.0.0.1:3306 ```
Based on the exhibit, what is the most likely cause of the repeated connection refused errors?
⚠ Common exam trap
CompTIA often tests the distinction between 'connection refused' (service down) and 'connection timeout' (firewall blocking) — candidates confuse the two because both prevent access, but the TCP error message uniquely identifies the cause.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The database service is down.
The 'connection refused' error indicates that the client's TCP SYN packet reached the target host on port 3306, but the host actively rejected the connection because no process is listening on that port. This is the classic symptom of the MySQL/MariaDB database service being stopped or crashed, as the OS TCP stack sends an RST packet when a connection attempt hits a port with no listening socket.
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 DNS resolution for the database host fails.
Why it's wrong here
A DNS failure produces name-resolution errors such as "unknown host", not connection refused, which means the name resolved but the TCP handshake was actively rejected. DNS troubleshooting would be the right path when clients cannot translate the database hostname at all.
- ✗
A firewall is blocking port 3306.
Why it's wrong here
A firewall blocking port 3306 typically causes timeouts or silent drops, not immediate refusal; refusal means the packet reached the host and no listener accepted it. Firewall rules are the correct focus when traffic is filtered before reaching the service.
- ✓
The database service is down.
Why this is correct
Connection refused means the TCP port is reachable but nothing is listening, so the database service itself is not running. A firewall drop would typically time out rather than refuse, confirming the service is down.
- ✗
The database credentials are incorrect.
Why it's wrong here
Bad credentials yield authentication failures after the TCP session is established, whereas connection refused occurs before any login exchange. Credential correction is the right fix when logs show access-denied or authentication errors rather than refused sockets.
Visual reference
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Process Management and System Monitoring
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
Key term
Process
In IT service management, a process is a structured set of activities designed to accomplish a specific objective, such as managing incidents or changes, by transforming inputs into defined outputs.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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