FirstTry
Objective 4.3XK0-005

4.3 Given a scenario, analyze and troubleshoot central processing unit (CPU) and memory issues.

Objective 4.3 sits in Troubleshooting, which carries 28% of the Linux+ exam. The questions below are original, written from the official objective title above, and each explanation cites the CompTIA page it rests on.

Objective title verbatim from the official objectives. CompTIA exam page ↗

A worked example

Shown solved, with the whole explanation open: this is what every question here carries.

4-3TroubleshootingModerate

A server shows very little free memory but no performance problem. Which free output column says how much memory new applications can use without swapping?

availableCorrect · your answerCorrect. This is the headroom estimate.
freefree counts only unused memory and ignores reclaimable cache.
buff/cachebuff/cache is the kernel's current cache use, not usable headroom directly.
sharedshared reports tmpfs-backed memory, not application headroom.

Correct.

Concept

Memory the kernel holds as cache is reclaimable, so the number that matters for headroom is an estimate that accounts for reclaim, not the untouched remainder.

Why A

The available column estimates how much memory can be used for starting new applications without swapping, which is the headroom the question asks about.

Source

#memory#free-command

Now you: objective 4.3 questions

No account needed. The explanation opens when you answer.

Sample question 1 of 3

4-3TroubleshootingHard

A monitoring agent alarms on the used memory column climbing. An engineer notes the alarm misreads the field. How is used actually calculated?

Sample question 2 of 3

4-3TroubleshootingEasy

Where does the free command get the memory figures it displays?

Sample question 3 of 3

4-3TroubleshootingModerate

An engineer wants kernel buffers and page cache reported as two separate columns instead of one combined figure. Which free option does that?

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Read the sources

These are the official pages the questions above cite. Reading them is studying the objective from the primary source, which is what the explanations point you toward anyway.