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.
Exhibit
Refer to the exhibit.
smb.conf (partial):
[global]
workgroup = EXAMPLE
security = user
idmap config * : backend = tdb2
idmap config * : range = 10000-20000
[nfs_share]
path = /srv/nfs/share
browseable = no
guest ok = no
What is the purpose of the 'idmap config * : backend = tdb2' line?
Refer to the exhibit.
smb.conf (partial):
[global]
workgroup = EXAMPLE
security = user
idmap config * : backend = tdb2
idmap config * : range = 10000-20000
[nfs_share]
path = /srv/nfs/share
browseable = no
guest ok = no
A
It sets the default identity mapping backend to tdb2.
The backend for the * (default) domain is set to tdb2.
B
It specifies the security mode as user.
Why wrong: Security mode is set by security = user, not idmap config.
C
It defines the default domain for Samba.
Why wrong: The default domain is * itself, but the line only sets its backend.
D
It enables the winbind cache.
Why wrong: Caching is separate (winbind cache time).
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It sets the default identity mapping backend to tdb2.
The 'idmap config * : backend = tdb2' line in Samba's smb.conf configures the default identity mapping backend for all domains not explicitly specified. The asterisk (*) acts as a wildcard representing any domain, and 'tdb2' is a high-performance, clustered-aware database backend that stores mappings between Windows SIDs and Unix UIDs/GIDs. This ensures that when a user or group from an unspecified domain is encountered, Samba uses tdb2 to manage the ID mapping, making option A correct.
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.
✓
It sets the default identity mapping backend to tdb2.
Why this is correct
The backend for the * (default) domain is set to tdb2.
Related concept
Read the scenario before looking for a memorised answer.
✗
It specifies the security mode as user.
Why it's wrong here
Security mode is set by security = user, not idmap config.
✗
It defines the default domain for Samba.
Why it's wrong here
The default domain is * itself, but the line only sets its backend.
✗
It enables the winbind cache.
Why it's wrong here
Caching is separate (winbind cache time).
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the wildcard '*' in idmap config with a domain-specific setting, thinking it applies only to a domain named '*', or they mistakenly associate it with security modes or domain definitions, rather than recognizing it as the default backend for all unspecified domains.
Detailed technical explanation
How to think about this question
The tdb2 backend is an improved version of the original tdb (Trivial Database) that supports concurrent access and clustering, making it suitable for environments with multiple Samba servers sharing the same ID mapping database. When 'idmap config * : backend = tdb2' is used, Samba automatically creates and manages a tdb2 file (typically /var/lib/samba/winbindd_idmap.tdb) to store SID-to-UID/GID mappings, and it handles the 'idmap range' parameter to define the allowed UID/GID range for mapped IDs. This is critical in mixed environments where Windows users from untrusted domains or local machine accounts need consistent Unix identity mapping.
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: It sets the default identity mapping backend to tdb2. — The 'idmap config * : backend = tdb2' line in Samba's smb.conf configures the default identity mapping backend for all domains not explicitly specified. The asterisk (*) acts as a wildcard representing any domain, and 'tdb2' is a high-performance, clustered-aware database backend that stores mappings between Windows SIDs and Unix UIDs/GIDs. This ensures that when a user or group from an unspecified domain is encountered, Samba uses tdb2 to manage the ID mapping, making option A correct.
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.
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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