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 uses 'security = domain' with an NT4-style domain. After a domain controller outage, users cannot authenticate. Which configuration change would allow fallback to local authentication?
Set 'domain master = no'
Why wrong: Incorrect; this affects browsing, not authentication.
Set 'security = user' and 'passdb backend = tdbsam'
Correct; switches to local authentication mode.
Set 'local master = yes'
Why wrong: Incorrect; this affects browsing, not authentication.
Set 'preferred master = no'
Why wrong: Incorrect; this affects browsing, not authentication.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Set 'security = user' and 'passdb backend = tdbsam'
When a Samba server is configured with 'security = domain', it relies on a remote NT4-style domain controller for authentication. If the domain controller is unavailable, users cannot authenticate because Samba has no local fallback. Changing to 'security = user' and setting 'passdb backend = tdbsam' switches Samba to authenticate users against its own local password database (tdbsam), allowing authentication even when the domain controller is down.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Set 'domain master = no'
Why it's wrong here
Incorrect; this affects browsing, not authentication.
Set 'security = user' and 'passdb backend = tdbsam'
Why this is correct
Correct; switches to local authentication mode.
Related concept
Read the scenario before looking for a memorised answer.
Set 'local master = yes'
Why it's wrong here
Incorrect; this affects browsing, not authentication.
Set 'preferred master = no'
Why it's wrong here
Incorrect; this affects browsing, not authentication.
Common exam traps
The trap here is that candidates confuse Samba's browsing roles (domain master, local master, preferred master) with authentication modes, assuming a browsing parameter can provide authentication fallback.
Detailed technical explanation
Under the hood, 'security = domain' uses Samba's winbindd to authenticate via MS-RPC calls to a domain controller. When the DC is unreachable, winbindd cannot validate credentials, and no local passdb backend is consulted. Switching to 'security = user' with 'passdb backend = tdbsam' bypasses winbindd entirely, using the local TDB-based password database for authentication. In real-world scenarios, administrators often configure a secondary authentication method (e.g., LDAP or a local fallback) to avoid this single point of failure.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
File Sharing and Samba — This question tests File Sharing and Samba — Read the scenario before looking for a memorised answer..
The correct answer is: Set 'security = user' and 'passdb backend = tdbsam' — When a Samba server is configured with 'security = domain', it relies on a remote NT4-style domain controller for authentication. If the domain controller is unavailable, users cannot authenticate because Samba has no local fallback. Changing to 'security = user' and setting 'passdb backend = tdbsam' switches Samba to authenticate users against its own local password database (tdbsam), allowing authentication even when the domain controller is down.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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.
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