LPIC-2 File Sharing and Samba Practice Question
A company has a Samba server configured as a domain member in an Active Directory domain. The server runs Samba 4.13. Recently, Windows clients have been unable to access shares, and the domain join seems broken. The administrator runs 'net ads testjoin' and gets 'Join to domain is not valid'. The smb.conf includes: security = ads, realm = EXAMPLE.COM, workgroup = EXAMPLE. The administrator can successfully resolve the domain controller via DNS. What should the administrator do to fix the issue?
⚠ Common exam trap
Watch out — candidates often confuse a broken domain join with a simple service restart or trust test, but the 'Join to domain is not valid' error specifically indicates the machine account credentials are invalid and require a fresh join.
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
✓
Re-run 'net ads join -U administrator' to rejoin the domain.
The 'net ads testjoin' command returned 'Join to domain is not valid', which indicates the machine account password stored in the local secrets.tdb file no longer matches the one in Active Directory. Re-running 'net ads join -U administrator' re-establishes the secure channel by resetting the machine account password and updating the Kerberos keytab, restoring the domain membership.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Re-run 'net ads join -U administrator' to rejoin the domain.
Why this is correct
This re-establishes the domain membership.
- ✗
Restart the winbind service and run 'wbinfo -t'.
Why it's wrong here
This tests trust, does not rejoin the domain.
- ✗
Add 'kerberos method = secrets and keytab' to smb.conf.
Why it's wrong here
This is the default, not a fix.
- ✗
Increase the 'log level' to 3 and restart smbd.
Why it's wrong here
This only increases logging, it does not fix the join.
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JA
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.