LPIC-2 File Sharing and Samba Practice Question
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?
⚠ Common exam trap
It's easy for candidates to 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.
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 Samba server's cached credentials for these users have expired and not been refreshed.
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.
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.
- ✗
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-2 exam.