GH-100 Question #48: Real Exam Question with Answer & Explanation

Question

Which feature is unique to self-hosted runners?

Options

• AExecute scripts before and after a job
• BDynamic scaling
• CAutomatic updates to the operating system
• DGPU support

Explanation

Self-hosted runners support runner hooks - shell scripts that execute automatically before and after every job via environment variables like ACTIONS_RUNNER_HOOK_JOB_STARTED and ACTIONS_RUNNER_HOOK_JOB_COMPLETED. This capability is exclusively available to self-hosted runner administrators and has no equivalent on GitHub-hosted runners, making A the correct answer.

Why the distractors are wrong:

• B (Dynamic scaling): This is a built-in characteristic of GitHub-hosted runners, which spin up and tear down on demand. Self-hosted runners require manual setup (e.g., actions-runner-controller) to scale dynamically - it's not unique to them.
• C (Automatic OS updates): This applies to GitHub-hosted runners, not self-hosted. Self-hosted runners require you to manage and patch the OS yourself, which is a common maintenance burden.
• D (GPU support): Both runner types can support GPUs - GitHub now offers GPU-equipped larger runners, so this is not exclusive to self-hosted.

Memory tip: Think of self-hosted runners as "your server, your rules" - the one thing only you can configure on your own infrastructure is running custom hook scripts around jobs. GitHub can't give you that control on their managed runners.

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