LPIC-2 Linux Kernel and System Startup Practice Question
An administrator needs to add support for a new hardware device by compiling a kernel module. After compiling the module against the current kernel source, the module fails to load with 'modprobe: ERROR: could not insert 'mymod': Unknown symbol in module'. Which of the following is the most likely cause?
⚠ Common exam trap
Candidates often confuse 'Unknown symbol' with missing dependencies (Option C), but the error specifically points to a symbol version mismatch, not a missing module dependency chain.
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 module was compiled against a different kernel version than the running kernel
The error 'Unknown symbol in module' indicates that the module references a kernel symbol (function or variable) that is not present in the currently running kernel. This most commonly occurs when the module was compiled against a different kernel version or configuration than the running kernel, causing symbol version mismatches. The kernel's symbol versioning (CONFIG_MODVERSIONS) checks CRC values of exported symbols, and a mismatch prevents insertion.
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 module has not been signed for Secure Boot
Why it's wrong here
Secure Boot issues produce a 'Required key not available' error, not 'Unknown symbol'.
- ✓
The module was compiled against a different kernel version than the running kernel
Why this is correct
Symbols exported by the kernel change between versions; the module must be compiled against the exact running kernel.
- ✗
The module's dependencies are missing
Why it's wrong here
Missing dependencies produce 'Unknown symbol' for symbols in dependencies, but the primary cause is usually a version mismatch.
- ✗
The module name conflicts with a built-in driver
Why it's wrong here
A name conflict would result in 'Module already present' or similar, not unknown symbols.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.