- A
The count file is not being written because the script lacks write permissions to /tmp.
Why wrong: If that were the case, the script would fail to write, and the count would never increment, so restarts would not occur.
- B
Multiple instances of the script are running concurrently due to cron timing, causing a race condition on the count file.
Without file locking, concurrent runs can overwrite each other's counts, leading to inaccurate failure counts and false restarts.
- C
The script does not reset the count file after a successful health check.
Why wrong: The script does reset the count file to 0 on success; that part is working correctly.
- D
The script does not handle the case where the count file does not exist on the first failure.
Why wrong: The script uses $((FAILS + 1)) and cat with default, which handles missing files correctly.
Quick Answer
The answer is a race condition on the count file caused by overlapping cron job instances. This occurs because the cron job runs the health check script every minute, but if the curl command to the local health endpoint takes longer than 60 seconds—due to network latency or a slow endpoint—multiple script instances execute concurrently. Each instance independently reads, increments, and writes the `/tmp/myapp_failcount` file, so a slow but healthy service can artificially inflate the fail counter past the threshold of three, triggering a false restart. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of cron job timing, file-based state management, and concurrency pitfalls in Bash scripting. A common trap is assuming cron guarantees serial execution, but it does not; overlapping jobs are a frequent source of debugging challenges. Remember the memory tip: "Cron doesn't queue—if one job lags, another starts, and your counter gets torn."
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. 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 Linux administrator is responsible for a critical application that runs as a systemd service on a server. The application occasionally hangs, and the administrator wants to automate the restart if the service becomes unresponsive. The administrator writes a Bash script that checks if the service is active and responsive by pinging a local health endpoint. If the health check fails three consecutive times, the script restarts the service. The script is intended to run every minute via a cron job. However, after implementing the cron job, the service is restarted even when it is functioning correctly, causing unnecessary downtime. The administrator reviews the script and finds the following logic:
#!/bin/bash SERVICE="myapp" COUNT_FILE="/tmp/${SERVICE}_failcount"
if curl -f http://localhost:8080/health; then
echo 0 > "$COUNT_FILE" else FAILS=$(cat "$COUNT_FILE" 2>/dev/null || echo 0) FAILS=$((FAILS + 1)) echo "$FAILS" > "$COUNT_FILE"
if [ "$FAILS" -ge 3 ]; then
systemctl restart "$SERVICE" echo 0 > "$COUNT_FILE" fi fi
What is the most likely cause of the false restarts?
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
Multiple instances of the script are running concurrently due to cron timing, causing a race condition on the count file.
Option B is correct because the cron job runs the script every minute, but if the health check takes longer than a minute (e.g., due to network latency or a slow endpoint), multiple instances of the script can overlap. Each instance reads, increments, and writes the count file independently, causing a race condition where the fail count can be artificially inflated, leading to a false restart even when the service is healthy.
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 count file is not being written because the script lacks write permissions to /tmp.
Why it's wrong here
If that were the case, the script would fail to write, and the count would never increment, so restarts would not occur.
- ✓
Multiple instances of the script are running concurrently due to cron timing, causing a race condition on the count file.
Why this is correct
Without file locking, concurrent runs can overwrite each other's counts, leading to inaccurate failure counts and false restarts.
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 script does not reset the count file after a successful health check.
Why it's wrong here
The script does reset the count file to 0 on success; that part is working correctly.
- ✗
The script does not handle the case where the count file does not exist on the first failure.
Why it's wrong here
The script uses $((FAILS + 1)) and cat with default, which handles missing files correctly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that a missing file or permission error is the root cause, when in reality the issue is a race condition from overlapping cron job executions.
Detailed technical explanation
How to think about this question
The race condition occurs because file-based locking is not used; when two script instances run concurrently, both may read the same initial fail count (e.g., 0), increment it to 1, and write back, so the actual count can be lower than expected or, more critically, one instance might read a stale value that another instance has already incremented, causing the count to jump to 3 prematurely. In production, this is often mitigated by using a lock file with `flock` or by redesigning the script to use a single atomic operation, such as a systemd timer with `OnFailure=` or a health check that updates a timestamp instead of a counter.
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 XK0-005 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.
- →
Scripting, Containers and Automation — study guide chapter
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Targeted practice on this topic area only
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CompTIA Linux+ XK0-005 study guide
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Multiple instances of the script are running concurrently due to cron timing, causing a race condition on the count file. — Option B is correct because the cron job runs the script every minute, but if the health check takes longer than a minute (e.g., due to network latency or a slow endpoint), multiple instances of the script can overlap. Each instance reads, increments, and writes the count file independently, causing a race condition where the fail count can be artificially inflated, leading to a false restart even when the service is healthy.
What should I do if I get this XK0-005 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 30, 2026
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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