The answer is an incorrect SELinux context on the binary, which must be changed to `bin_t`. When a service fails to start with a "Permission denied" error despite standard Linux permissions being correct (755), SELinux enforcing mode is the likely culprit. The binary's current context `usr_t` is a generic file type that the service's domain (typically `init_t` or a custom domain) is not allowed to execute; executables in `/usr/local/bin` require the `bin_t` type to be launched by system services. On the CompTIA Linux+ XK0-005 exam, this scenario tests your ability to distinguish between DAC (discretionary access control) and MAC (mandatory access control) failures—a common trap is checking file permissions first when SELinux is the real issue. The fix is straightforward: run `restorecon -v /usr/local/bin/myapp` to restore the default `bin_t` context. Memory tip: "If permissions look fine but the service won't start, think SELinux—restorecon is your friend."
XK0-005 System Management Practice Question
This XK0-005 practice question tests your understanding of system management. 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 custom application service 'myapp.service' fails to start on a RHEL 8 system with the error: "Failed at step EXEC spawning /usr/local/bin/myapp: Permission denied". The service runs as user 'myapp'. The binary /usr/local/bin/myapp has permissions 755 and is owned by root:root. The user myapp is not in the sudoers. The administrator checks SELinux and finds the binary has the context 'unconfined_u:object_r:usr_t:s0'. The service unit file does not specify any SELinux context. What is the most likely cause of the failure?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The SELinux context of the binary is incorrect; it should be bin_t.
The error occurs because SELinux is enforcing and the binary has the type 'usr_t', which is not allowed to be executed by the service's domain (probably init_t or custom domain). The correct type for executables in /usr/local/bin is 'bin_t'. The solution is to restore the SELinux context to the default for binaries using `restorecon -v /usr/local/bin/myapp` or changing it to bin_t. Option A is incorrect because permissions allow execution. Option C is unlikely because /usr/local/bin is in PATH. Option D is incorrect as user has execute permission.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 user myapp does not have read access to the binary.
Why it's wrong here
755 grants read and execute to all users.
✓
The SELinux context of the binary is incorrect; it should be bin_t.
Why this is correct
The binary has usr_t context, which is not allowed for execution by the service; restoring to bin_t fixes it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The binary is located in a directory that is not in the systemd safe path.
Why it's wrong here
/usr/local/bin is in the default secure path for systemd services.
✗
The binary is not executable by myapp due to file permissions.
Why it's wrong here
755 allows others to execute, so user myapp can execute it.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related XK0-005 NAT questions on configuration and troubleshooting.
System Management — This question tests System Management — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The SELinux context of the binary is incorrect; it should be bin_t. — The error occurs because SELinux is enforcing and the binary has the type 'usr_t', which is not allowed to be executed by the service's domain (probably init_t or custom domain). The correct type for executables in /usr/local/bin is 'bin_t'. The solution is to restore the SELinux context to the default for binaries using `restorecon -v /usr/local/bin/myapp` or changing it to bin_t. Option A is incorrect because permissions allow execution. Option C is unlikely because /usr/local/bin is in PATH. Option D is incorrect as user has execute permission.
What should I do if I get this XK0-005 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related XK0-005 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user reports that a custom application service fails to start with a 'Permission denied' error in the logs. The service runs under the 'appuser' account. Which is the most likely cause and the first step to diagnose?
medium
A.The root password is incorrect; change root password with passwd.
✓ B.SELinux is blocking the service; check journalctl for AVC denials and use restorecon or setsebool.
C.The service binary does not have execute permission for appuser; use chmod +x.
D.The systemd target is not set to multi-user; run systemctl set-default multi-user.target.
Why B: Option B is correct because SELinux denials are a common cause of permission errors for services; journalctl can reveal the SELinux denial message. Option A: file permissions might be an issue but SELinux is more likely with a service; C: root password does not affect service startup; D: systemd targets are for runlevel, not file access.
Last reviewed: Jun 24, 2026
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This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.
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