LFCS Operation of Running Systems Practice Question
A system with systemd experiences a service that fails to start due to a 'Failed to start' error with status 203/EXEC. What is the most likely cause?
⚠ Common exam trap
Test-takers frequently confuse status 203/EXEC with a generic 'service failed to start' and incorrectly attribute it to dependencies or resource exhaustion, rather than recognizing it as a specific indicator of an exec() failure in the ExecStart directive.
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 service unit file has a missing or incorrect ExecStart command
Status 203/EXEC in systemd indicates that the service manager failed to execute the command specified in the service unit file. The most common cause is a missing or incorrect ExecStart directive, such as a typo in the binary path, a missing executable, or incorrect syntax. This error is specific to execution failures, not resource or dependency issues.
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 system has run out of memory
Why it's wrong here
Status 203/EXEC means systemd could not execute the binary, typically from a missing file, wrong path or absent execute permission. Out-of-memory conditions produce status 203/EXEC only rarely; they manifest as OOM-killer terminations or status 137, so memory exhaustion is not the likely cause here.
- ✓
The service unit file has a missing or incorrect ExecStart command
Why this is correct
Status 203/EXEC means systemd could not execute the binary specified in ExecStart, typically because the path is wrong, the file lacks execute permission, or the interpreter is missing. Correcting the ExecStart directive resolves the failure.
- ✗
The service is already running
Why it's wrong here
An already-running service does not produce 203/EXEC; systemd reports it as active or returns a start-limit or already-active result. Status 203/EXEC specifically indicates the ExecStart binary could not be executed, so this option misidentifies the failure mechanism entirely.
- ✗
The service requires a dependency that hasn't started
Why it's wrong here
Missing dependencies cause ordering or dependency failures, reported as status 203/EXEC only indirectly; systemd normally logs dependency errors or status 1. Status 203/EXEC points to the ExecStart binary itself being unexecutable, so a dependency problem is not the most likely cause.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.