Quick Answer
The answer is /etc/cron.allow, which is the file used to configure which users and groups are allowed to use the cron daemon. This file operates as a whitelist: when it exists, only the users and groups explicitly listed within it can schedule cron jobs via crontab, and all others are denied access, regardless of any entries in /etc/cron.deny. On the LPIC-2 exam, this concept tests your understanding of cron’s access control hierarchy and the principle of explicit permission, often appearing as a scenario where you must choose the correct file to restrict users. A common trap is assuming /etc/cron.deny is the primary control, but remember that /etc/cron.allow takes precedence when both files exist, making it the definitive tool for restricting cron usage. For a quick memory tip, think “allow first” — if the allow file exists, it alone decides who gets in, just like a VIP list at an exclusive event.
This LPIC-2 practice question tests your understanding of system security. 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.
Which file is used to configure which users and groups are allowed to use the 'cron' daemon?
/var/spool/cron/
Why wrong: Directory containing user crontab files.
/etc/cron.d/
Why wrong: Directory for system cron jobs.
/etc/crontab
Why wrong: System crontab file, not for user access control.
/etc/cron.allow
Lists users allowed to use cron.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
/etc/cron.allow
The /etc/cron.allow file explicitly lists users and groups permitted to schedule cron jobs. If this file exists, only those entries can use crontab; all others are denied, regardless of /etc/cron.deny. This provides a whitelist-based access control mechanism for the cron daemon.
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.
/var/spool/cron/
Why it's wrong here
Directory containing user crontab files.
/etc/cron.d/
Why it's wrong here
Directory for system cron jobs.
/etc/crontab
Why it's wrong here
System crontab file, not for user access control.
/etc/cron.allow
Why this is correct
Lists users allowed to use cron.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse the access control files (/etc/cron.allow and /etc/cron.deny) with the directories or system crontab files that store or schedule jobs, such as /var/spool/cron/ or /etc/crontab.
Detailed technical explanation
Under the hood, cron checks /etc/cron.allow first; if it exists, the user must be listed (one per line) to be allowed. If /etc/cron.allow does not exist, cron falls back to /etc/cron.deny, which blocks listed users. If neither file exists, only root can use crontab on most systems (e.g., Debian/Ubuntu allow all users by default, but this varies). A subtle behavior: group names can be prefixed with '@' in some implementations (e.g., @admin), though this is not POSIX-standard.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
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FAQ
System Security — This question tests System Security — Read the scenario before looking for a memorised answer..
The correct answer is: /etc/cron.allow — The /etc/cron.allow file explicitly lists users and groups permitted to schedule cron jobs. If this file exists, only those entries can use crontab; all others are denied, regardless of /etc/cron.deny. This provides a whitelist-based access control mechanism for the cron daemon.
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 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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