LFCS Operation of Running Systems Practice Question
This LFCS practice question tests your understanding of operation of running systems. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
[root@server ~]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Mon 2025-03-10 09:23:45 UTC; 2min ago
Process: 12345 ExecStart=/usr/sbin/nginx (code=exited, status=1/FAILURE)
Main PID: 12345 (code=exited, status=1/FAILURE)
Mar 10 09:23:43 server systemd[1]: Starting The nginx HTTP and reverse proxy server...
Mar 10 09:23:45 server nginx[12345]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Mar 10 09:23:45 server systemd[1]: nginx.service: Main process exited, code=exited, status=1/FAILURE
Mar 10 09:23:45 server systemd[1]: nginx.service: Failed with result 'exit-code'.
Based on the exhibit, what is the most likely cause of the nginx failure and the appropriate first step to resolve it?
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.
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.
[root@server ~]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Mon 2025-03-10 09:23:45 UTC; 2min ago
Process: 12345 ExecStart=/usr/sbin/nginx (code=exited, status=1/FAILURE)
Main PID: 12345 (code=exited, status=1/FAILURE)
Mar 10 09:23:43 server systemd[1]: Starting The nginx HTTP and reverse proxy server...
Mar 10 09:23:45 server nginx[12345]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
Mar 10 09:23:45 server systemd[1]: nginx.service: Main process exited, code=exited, status=1/FAILURE
Mar 10 09:23:45 server systemd[1]: nginx.service: Failed with result 'exit-code'.
A
Restart the nginx service.
Why wrong: Restarting will not free the port; the same error will occur.
B
Check which process is listening on port 80 with 'ss -tlnp' and stop that process.
Port 80 is already in use; identify and stop the conflicting process.
C
Increase the worker_connections in nginx.conf.
Why wrong: worker_connections controls concurrent connections, not binding to a port.
D
Reduce the MaxClients parameter in nginx.conf.
Why wrong: MaxClients is not a valid nginx directive; it is Apache.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check which process is listening on port 80 with 'ss -tlnp' and stop that process.
Option B is correct because the error 'Address already in use' indicates port 80 is occupied by another process. Checking with 'ss -tlnp' or 'lsof' identifies the offending process. Option A is incorrect as restarting would fail again. Option C is incorrect because MaxClients is an Apache directive, not nginx. Option D is incorrect because worker_connections affects performance, not binding.
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.
✗
Restart the nginx service.
Why it's wrong here
Restarting will not free the port; the same error will occur.
✓
Check which process is listening on port 80 with 'ss -tlnp' and stop that process.
Why this is correct
Port 80 is already in use; identify and stop the conflicting process.
Clue confirmation
The clue words "first", "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the worker_connections in nginx.conf.
Why it's wrong here
worker_connections controls concurrent connections, not binding to a port.
✗
Reduce the MaxClients parameter in nginx.conf.
Why it's wrong here
MaxClients is not a valid nginx directive; it is Apache.
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 practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which LFCS 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.
Operation of Running Systems — This question tests Operation of Running Systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Check which process is listening on port 80 with 'ss -tlnp' and stop that process. — Option B is correct because the error 'Address already in use' indicates port 80 is occupied by another process. Checking with 'ss -tlnp' or 'lsof' identifies the offending process. Option A is incorrect as restarting would fail again. Option C is incorrect because MaxClients is an Apache directive, not nginx. Option D is incorrect because worker_connections affects performance, not binding.
What should I do if I get this LFCS question wrong?
Identify which LFCS 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", "most likely". 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.
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