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 company runs a mixed environment with Linux and Windows clients. The Samba server is configured as a domain member for authentication. Users authenticate via Active Directory using winbind. Recently, the IT department implemented a new password policy that requires all users to change passwords every 90 days. After the policy took effect, several users report that they cannot access Samba shares from their Linux clients (using smbclient) even though they can log into their Windows desktops with the same credentials. The error message on Linux is 'session setup failed: NT_STATUS_LOGON_FAILURE'. The administrator runs 'wbinfo -a username%password' and it succeeds. 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 Samba server's cached credentials for these users have expired and not been refreshed.
Option C is correct because when a Samba server is a domain member using winbind, it caches user credentials to reduce authentication traffic to the domain controller. After the new 90-day password policy, users changed their passwords on Windows, but the cached credentials on the Samba server were not refreshed. The `wbinfo -a` command succeeds because it contacts the domain controller directly, bypassing the cache, while `smbclient` fails because it uses the stale cached credentials, resulting in NT_STATUS_LOGON_FAILURE.
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 Samba server's krb5.conf is misconfigured for the new password policy.
Why it's wrong here
The error NT_STATUS_LOGON_FAILURE is typical of NTLM failure, not Kerberos.
✗
The users' passwords contain characters that are not being encoded correctly by smbclient.
Why it's wrong here
wbinfo also uses the same encoding, so if it succeeds, encoding is fine.
✓
The Samba server's cached credentials for these users have expired and not been refreshed.
Why this is correct
Winbind caches credentials; after a password change, the cache may be stale.
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 Linux clients are using an older version of Samba that does not support the new password policy.
Why it's wrong here
Samba version compatibility is not the issue; newer patches support password policies.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume `wbinfo -a` success means the Samba server is fully functional, overlooking that cached credentials can cause failures for tools that rely on the cache, such as `smbclient` or mount.cifs.
Detailed technical explanation
How to think about this question
Winbind caches credentials in the `tdb` database files (e.g., `secrets.tdb`, `winbindd_cache.tdb`) to improve performance and allow offline authentication. When a user changes their password on the domain controller, the cached password hash on the Samba server becomes stale. The `wbinfo -a` command performs a fresh authentication against the DC, while `smbclient` uses the cached session key. Administrators can force a cache refresh by running `net cache flush` or restarting winbind services, or by configuring `winbind offline logon = no` to disable caching.
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 Samba server's cached credentials for these users have expired and not been refreshed. — Option C is correct because when a Samba server is a domain member using winbind, it caches user credentials to reduce authentication traffic to the domain controller. After the new 90-day password policy, users changed their passwords on Windows, but the cached credentials on the Samba server were not refreshed. The `wbinfo -a` command succeeds because it contacts the domain controller directly, bypassing the cache, while `smbclient` fails because it uses the stale cached credentials, resulting in NT_STATUS_LOGON_FAILURE.
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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