Quick Answer
The answer is enabling winbind offline logon and setting the idmap config * backend to tdb. These two changes improve Samba authentication performance by reducing reliance on the domain controller for repeated operations: winbind offline logon caches user credentials locally so authentication can proceed without network round trips, while the tdb backend stores ID mappings (UID/GID to SID) in a local database, eliminating costly queries to the DC for every mapping resolution. On the LPIC-2 exam, this tests your understanding of Samba domain member optimization under Objective 210.2, where a common trap is confusing caching with security—offline logon does not weaken authentication, it simply reduces latency. Remember the mnemonic “Cache the creds, map the IDs” to recall that both changes keep data local, directly addressing slow authentication performance in a domain member setup.
This LPIC-2 practice question tests your understanding of file sharing and samba. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 Linux server running Samba as a domain member is experiencing slow authentication for users. Which two configuration changes are most likely to improve authentication performance?
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.
Disable SMB signing by setting 'server signing = disabled'
Why wrong: Causes protocol errors
Enable 'winbind offline logon = yes'
Allows cached logon
Set 'idmap config * : backend = tdb' to cache ID mappings locally
Caching reduces LDAP queries
Change 'security = ADS' to 'security = user'
Why wrong: Breaks domain membership
Set 'name resolve order = lmhosts host wins bcast'
Why wrong: Does not improve authentication speed
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Enable 'winbind offline logon = yes'
Option B is correct because enabling 'winbind offline logon = yes' allows winbind to cache user credentials locally, so authentication can proceed without contacting the domain controller if it is temporarily unreachable, reducing latency for repeated logins. Option C is correct because setting 'idmap config * : backend = tdb' stores ID mappings (UID/GID to SID) in a local tdb database, avoiding repeated queries to the domain controller for mapping resolution, which directly improves authentication performance in a domain member setup.
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.
Disable SMB signing by setting 'server signing = disabled'
Why it's wrong here
Causes protocol errors
Enable 'winbind offline logon = yes'
Why this is correct
Allows cached logon
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.
Set 'idmap config * : backend = tdb' to cache ID mappings locally
Why this is correct
Caching reduces LDAP queries
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.
Change 'security = ADS' to 'security = user'
Why it's wrong here
Breaks domain membership
Set 'name resolve order = lmhosts host wins bcast'
Why it's wrong here
Does not improve authentication speed
Common exam traps
The trap here is that candidates often confuse 'performance improvements' with 'security reductions' (like disabling SMB signing) or 'name resolution tweaks', when the actual bottleneck is typically the round-trip time to the domain controller for authentication and ID mapping lookups, which caching directly addresses.
Detailed technical explanation
Under the hood, winbindd uses the DCE/RPC protocol to communicate with domain controllers for authentication and ID mapping. Enabling offline logon leverages the 'credentials.tdb' file to store hashed passwords, allowing logins even when the DC is unreachable, while the tdb idmap backend stores mappings in a local database (idmap_cache.tdb) that persists across reboots, reducing LDAP or RPC calls. In real-world scenarios with high-latency WAN links to the DC, these two changes can cut authentication time from seconds to milliseconds for cached users.
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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: Enable 'winbind offline logon = yes' — Option B is correct because enabling 'winbind offline logon = yes' allows winbind to cache user credentials locally, so authentication can proceed without contacting the domain controller if it is temporarily unreachable, reducing latency for repeated logins. Option C is correct because setting 'idmap config * : backend = tdb' stores ID mappings (UID/GID to SID) in a local tdb database, avoiding repeated queries to the domain controller for mapping resolution, which directly improves authentication performance in a domain member setup.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 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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