- A
The 'valid users = @staff' directive excludes root, so users cannot write because the share is owned by root.
Why wrong: Incorrect. valid users controls access, not ownership. Root is not a user in staff, but users are staff.
- B
The 'force group = staff' parameter overrides file ownership and prevents writes because the files are owned by root.
Why wrong: Incorrect. force group changes group, but ownership remains; with 664 permissions, group can write.
- C
The global 'map to guest = Bad User' setting is causing users who mistype their password to be mapped to the guest account, losing write permissions.
Correct. This is a common misconfiguration; users connect as guest if password fails, and guest may not have write access.
- D
The 'create mask = 0660' is too restrictive and prevents users from writing to existing files.
Why wrong: Incorrect. Create mask only affects new files, not existing ones.
Quick Answer
The answer is the global 'map to guest = Bad User' setting, which causes users who mistype their password to be mapped to the guest account, stripping their write permissions. This occurs because Samba’s authentication process, when encountering a failed login due to a typo or incorrect password, silently downgrades the connection to the guest account rather than rejecting it outright. Since the share lacks a 'guest ok' directive and the guest account typically has no write access to /data, users connected as guest cannot modify files despite the share being set to read only = no. On the LPIC-2 exam, this scenario tests your understanding of Samba’s authentication flow and the interaction between global and share-level settings—a common trap is assuming the share’s permissions are the sole culprit. Remember the mnemonic: “Bad User maps to guest, good user maps to write.”
LPIC-2 File Sharing and Samba Practice Question
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.
You are the administrator for a small office network with 20 Linux workstations and 5 Windows 10 clients. The company uses a Samba server (version 4.15) running on Ubuntu 22.04 to share a central directory /data with user-level security. Each user has a home directory on the server, and all users are in the 'staff' group. Recently, users have complained that they can access the /data share from Windows but cannot modify any files, even though they could before. The Samba configuration for the share is:
[data]
path = /data browseable = yes read only = no valid users = @staff create mask = 0660 directory mask = 0770 force group = staff
You check the filesystem permissions on /data and find it is owned by root:staff with permissions 775. Files inside are owned by individual users and group staff with permissions 664. You also check smbstatus and see that users are connected as 'guest' rather than their actual username. What is the most likely cause of the problem?
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.
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 global 'map to guest = Bad User' setting is causing users who mistype their password to be mapped to the guest account, losing write permissions.
The 'map to guest = Bad User' global setting in Samba causes any user who fails authentication (e.g., due to a typo or incorrect password) to be mapped to the guest account. Since the share does not define a 'guest ok' or 'guest only' setting, and the guest account typically has no write permissions on the /data directory, users connected as guest cannot modify files. The smbstatus output confirming users are connected as 'guest' directly points to this misconfiguration.
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.
- ✗
The 'valid users = @staff' directive excludes root, so users cannot write because the share is owned by root.
Why it's wrong here
Incorrect. valid users controls access, not ownership. Root is not a user in staff, but users are staff.
- ✗
The 'force group = staff' parameter overrides file ownership and prevents writes because the files are owned by root.
Why it's wrong here
Incorrect. force group changes group, but ownership remains; with 664 permissions, group can write.
- ✓
The global 'map to guest = Bad User' setting is causing users who mistype their password to be mapped to the guest account, losing write permissions.
Why this is correct
Correct. This is a common misconfiguration; users connect as guest if password fails, and guest may not have write access.
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.
- ✗
The 'create mask = 0660' is too restrictive and prevents users from writing to existing files.
Why it's wrong here
Incorrect. Create mask only affects new files, not existing ones.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on filesystem permissions or mask values, overlooking the global 'map to guest' setting which silently downgrades authenticated users to guest, stripping write access despite correct share-level permissions.
Detailed technical explanation
How to think about this question
The 'map to guest' parameter in smb.conf controls how Samba handles authentication failures. When set to 'Bad User', any user who provides an incorrect username or password is automatically treated as the guest account (typically 'nobody'). This is often used to allow anonymous access to public shares, but if the share requires write permissions and the guest account lacks them (or the share does not have 'guest ok = yes'), users will lose write capability. The smbstatus command reveals the effective user identity, making it a key diagnostic tool.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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.
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File Sharing and Samba — study guide chapter
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FAQ
Questions learners often ask
What does this LPIC-2 question test?
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: The global 'map to guest = Bad User' setting is causing users who mistype their password to be mapped to the guest account, losing write permissions. — The 'map to guest = Bad User' global setting in Samba causes any user who fails authentication (e.g., due to a typo or incorrect password) to be mapped to the guest account. Since the share does not define a 'guest ok' or 'guest only' setting, and the guest account typically has no write permissions on the /data directory, users connected as guest cannot modify files. The smbstatus output confirming users are connected as 'guest' directly points to this misconfiguration.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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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