# Knowledge Check: Deployments & Rollouts

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**1. A rolling update to a new image version has been "in progress" for 20 minutes with no
error message, and `kubectl rollout status` never returns. What's the first thing you should
check, and why?**

*Answer:* `kubectl get pods` to see the new Pod's status, then `kubectl describe pod` on it if
it isn't `Running`. A stalled rollout with no explicit error almost always means a new Pod can't
become Ready — commonly `ImagePullBackOff` (bad image/tag) or a failing readiness probe. The
rollout isn't broken; it's correctly refusing to proceed until the new Pod proves healthy.

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**2. True or false: `kubectl rollout undo` restores your application from a backup of its
previous state.**

*Answer:* False. It scales the previous (still-present, just scaled-to-zero) ReplicaSet back up
and the current one back down — the same rolling mechanism as a forward update, just pointed at
an older, already-proven-working Pod template. Nothing is being restored from storage.

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**3. A Deployment has `replicas: 3`. You need it to handle more traffic. Which is the correct
action: edit the Pod template's resource limits, or change the replica count? Justify your
answer for a stateless web application.**

*Answer:* Change the replica count (scale out) for a stateless application handling more
concurrent traffic — more identical copies sharing the load. Changing resource limits affects
how much each individual Pod can use, not how many Pods exist; it doesn't add capacity for more
concurrent requests the way scaling does.

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**4. Why does a Deployment keep an old, scaled-to-zero ReplicaSet around instead of deleting it
immediately after a successful rollout?**

*Answer:* That scaled-down ReplicaSet is exactly what makes fast, safe rollback possible later —
deleting it immediately would mean a "rollback" would have to rebuild the old Pod template from
scratch (or fail entirely) instead of simply scaling existing, already-defined Pods back up.

## Instructor Notes

**Facilitation:** Question 1 is the most important one to discuss out loud — it's the exact
diagnostic instinct students will need repeatedly in ROOT 10.

**Approximate timing:** 5 minutes.