This LPIC-2 practice question tests your understanding of file sharing and samba. 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 Samba server configured as an Active Directory domain member is unable to authenticate users from the domain. The administrator verifies that DNS resolution works, but `wbinfo -u` returns no output. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The winbind service is not running.
The `wbinfo -u` command queries the winbind service to list domain users. If it returns no output, the most likely cause is that the winbind service is not running, as it is responsible for resolving Windows domain users and groups on a Samba member server. Without winbind, Samba cannot authenticate domain users even if DNS and Kerberos are working correctly.
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.
✗
The smb.conf file is missing the 'idmap config' lines.
Why it's wrong here
Missing idmap config may cause mapping issues but not necessarily empty `wbinfo -u` output.
✓
The winbind service is not running.
Why this is correct
If winbind is not running, `wbinfo -u` cannot retrieve domain users.
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.
✗
The Kerberos ticket is expired.
Why it's wrong here
Kerberos tickets affect authentication, but `wbinfo -u` uses the machine account, not user tickets.
✗
The system clock is not synchronized with the domain controller.
Why it's wrong here
Clock skew prevents Kerberos auth but does not cause `wbinfo -u` to return empty; winbind would still try.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume DNS or Kerberos issues are the root cause because they are common in domain authentication problems, but the specific symptom of `wbinfo -u` returning no output directly points to the winbind service not running, not to higher-layer protocol failures.
Trap categories for this question
Command / output trap
Missing idmap config may cause mapping issues but not necessarily empty `wbinfo -u` output.
Detailed technical explanation
How to think about this question
Winbind uses the MS-RPC protocol to communicate with domain controllers over ports 139/445, and it maintains its own credential cache separate from the Kerberos ticket cache. The `wbinfo -u` command specifically calls the `winbindd` daemon's `SAMR` or `LSARPC` interfaces to enumerate users; if the daemon is not running, the command fails silently or returns empty output. In real-world scenarios, administrators often forget to start or enable winbind after configuring Samba as a domain member, leading to this exact symptom.
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 practitioner preparing for the LPIC-2 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
File Sharing and Samba — This question tests File Sharing and Samba — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The winbind service is not running. — The `wbinfo -u` command queries the winbind service to list domain users. If it returns no output, the most likely cause is that the winbind service is not running, as it is responsible for resolving Windows domain users and groups on a Samba member server. Without winbind, Samba cannot authenticate domain users even if DNS and Kerberos are working correctly.
What should I do if I get this LPIC-2 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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Question Discussion
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