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CKA study material: Scheduling

107 questions of the 1000 in the CKA — Certified Kubernetes Administrator quiz. Each opens with its answer, the reasoning and where that is written down.

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The questions

1. 4. Which factors does kube-scheduler weigh when choosing a node for a Pod? Choose two.
2. 70. A Pod keeps running on a node that has been drained and marked unschedulable. What explains this?
3. 148. Which tolerations does the DaemonSet controller add to its Pods automatically? Choose two.
4. 164. Which is the simplest way to confine a Pod to nodes carrying a particular label?
5. 165. A Pod uses requiredDuringSchedulingIgnoredDuringExecution node affinity and no node matches. What happens?
6. 166. A running Pod's node loses the label its preferred node affinity matched. What does Kubernetes do?
7. 167. What range may the weight of a preferred node affinity rule take?
8. 168. A Pod has two preferred affinity rules, one weighted 1 and one weighted 50, and two nodes each satisfy one. Which node wins?
9. 169. Which command removes a taint that was added with kubectl taint nodes node1 key1=value1:NoSchedule?
10. 170. When does a toleration match a taint? Choose two.
11. 171. Which taint effect keeps new Pods away but leaves Pods already running on the node alone?
12. 172. How does tolerationSeconds affect a toleration for a NoExecute taint? Choose two.
13. 173. A node carries three taints and a Pod tolerates two of them, the untolerated one being NoSchedule. What is the outcome?
14. 174. What does a Pod's resource request actually reserve?
15. 175. A container specifies a memory limit but no memory request, and no default is applied. What request does it get?
16. 176. What does a CPU request of 0.5 mean?
17. 177. How does the runtime treat a container that exceeds its limits? Choose two.
18. 178. How many PriorityClasses may set globalDefault to true?
19. 179. A globalDefault PriorityClass is added to a cluster that already runs many Pods. What changes for them?
20. 180. A PriorityClass is deleted while Pods still reference it. What happens?
21. 181. What does setting preemptionPolicy to Never on a PriorityClass achieve?
22. 182. Which are eviction signals the kubelet compares against thresholds? Choose two.
23. 183. Which filesystem does the nodefs eviction signal describe?
24. 184. What distinguishes a hard eviction threshold from a soft one?
25. 185. What is the default hard eviction threshold for memory.available on a Linux node?
26. 186. Which two statements about soft eviction thresholds are correct? Choose two.
27. 187. Which inputs decide the kubelet's eviction order? Choose two.
28. 188. When is a Pod classified as Guaranteed?
29. 189. A static Pod must survive resource pressure. Why can it not use priorityClassName?
30. 190. In a topology spread constraint, what does topologyKey name?
31. 191. What is the default value of whenUnsatisfiable in a topology spread constraint?
32. 192. Two topology spread constraints use the same topologyKey. When is that allowed?
33. 193. Which two statements about minDomains are correct? Choose two.
34. 194. When does a namespace become subject to resource quota enforcement?
35. 195. A quota is written for an extended resource. Which prefix may its quota items use?
36. 196. A Deployment requesting more than the namespace quota allows is applied. What happens?
37. 197. What is the difference between a ResourceQuota and a LimitRange?
38. 198. What can a LimitRange enforce? Choose two.
39. 199. An object violating a LimitRange is submitted. What does the API server return?
40. 200. A LimitRange is added to a namespace that already runs Pods breaching it. What happens to those Pods?
41. 319. A cluster uses topology-constrained storage and Pods keep landing where their volume is unreachable. Which setting fixes this?
42. 321. A StorageClass uses WaitForFirstConsumer but a Pod sets nodeName directly. What is the consequence?
43. 331. What makes a local PersistentVolume safer to use than a hostPath volume?
44. 352. A Pod is stuck in Pending. What does that state tell you?
45. 353. Which remedies are suggested for a Pod pending through insufficient resources? Choose two.
46. 354. A Deployment using hostPort cannot schedule beyond a handful of replicas. Why?
47. 366. kubectl describe node shows both Capacity and Allocatable. What is the difference?
48. 381. Why might a Pod fail to schedule anywhere? Choose two.
49. 382. Why is a node's schedulable headroom smaller than its machine size suggests?
50. 520. An operator starts a container directly through the container runtime on a node, outside Kubernetes. How does the scheduler account for the resources it consumes?
51. 552. On a single-machine kubeadm cluster, ordinary workloads stay Pending. Which action lets them run?
52. 575. You are upgrading the kubelet on a control plane node across a minor version. Why must that node be drained first?
53. 646. How does a DaemonSet Pod come to be running on a particular node?
54. 647. A DaemonSet's Pods fail to schedule on nodes that are already full. Which change makes them able to displace other work?
55. 648. A node becomes unreachable and its ordinary Pods are eventually evicted, yet its DaemonSet Pods stay put. Why?
56. 664. A team adds a toleration for a GPU node's taint to every Pod in a Deployment, expecting them to land on the GPU nodes. What actually happens?
57. 665. An administrator adds a NoExecute taint to a node that is already running Pods. Which two things happen? Choose two.
58. 666. A node carries the taint tier=gold:NoSchedule. Which toleration matches it?
59. 667. A Pod carries a toleration with an empty key and the operator Exists, and no effect. What does it tolerate?
60. 668. A node has three taints and a Pod tolerates two of them; the untolerated one has effect NoSchedule. What is the outcome for a new Pod?
61. 669. A Pod tolerates a NoExecute taint and sets tolerationSeconds to 3600. The taint is applied at noon and removed at 12:30. What happens to the Pod?
62. 670. A Pod manifest sets spec.nodeName directly to a node carrying a NoExecute taint the Pod does not tolerate. What happens?
63. 671. What is the highest value an administrator may set on a custom PriorityClass?
64. 672. A cluster has no PriorityClass with globalDefault set. What priority does a Pod that names no class receive?
65. 673. An operator creates a PriorityClass with globalDefault: true in a running cluster. What effect does it have on the Pods already there?
66. 674. A data science team wants their long jobs scheduled ahead of others in the queue but never at the cost of evicting running work. Which PriorityClass setting achieves that?
67. 675. A Pod uses a PriorityClass with preemptionPolicy: Never. Can that Pod itself be preempted?
68. 676. A topology spread constraint sets maxSkew to 1 with whenUnsatisfiable: ScheduleAnyway. What does maxSkew mean here?
69. 677. A Pod spec has two topology spread constraints, both with topologyKey kubernetes.io/hostname and whenUnsatisfiable: DoNotSchedule. Why is this rejected?
70. 678. A topology spread constraint sets minDomains to 3 alongside whenUnsatisfiable: ScheduleAnyway. What is the problem?
71. 679. A Pod was scheduled using requiredDuringSchedulingIgnoredDuringExecution node affinity. An administrator later removes the matching label from the node. What happens to the Pod?
72. 680. A node affinity rule lists two entries under nodeSelectorTerms, each with one matchExpressions clause. When does a node satisfy the rule?
73. 681. What is the permitted range for the weight of a preferredDuringSchedulingIgnoredDuringExecution node affinity rule?
74. 682. A Pod sets both a nodeSelector for disk=ssd and a required node affinity for zone in [a, b]. Which nodes are eligible?
75. 683. An inter-pod anti-affinity rule uses topology.kubernetes.io/zone as its topologyKey, but several nodes have no such label. What is the documented consequence?
76. 684. Which two of the following are default hard eviction thresholds on a Linux node? Choose two.
77. 685. What distinguishes a soft eviction threshold from a hard one?
78. 686. A node reports the DiskPressure condition. Which eviction signal could have caused it?
79. 687. How does the kubelet calculate memory.available for eviction purposes?
80. 688. Which pair of steps describes how kube-scheduler chooses a node?
81. 689. Three nodes finish the scoring phase with identical scores. How does kube-scheduler choose between them?
82. 690. A Pod's requirements match no node in the cluster. What does kube-scheduler do?
83. 691. Which two of the following are extension points a scheduling profile can configure with plugins? Choose two.
84. 692. Which sequence does kubectl drain follow?
85. 693. An operator scripts a rolling reboot that drains five nodes at once. What risk does the documentation identify?
86. 694. A service owner writes a PodDisruptionBudget with minAvailable: 2 and expects it to survive a node's power supply failing. What does the budget actually guarantee?
87. 695. A drain hangs because the application's Pods are crash-looping and the PodDisruptionBudget will not allow their eviction. Which setting is recommended to avoid this?
88. 696. An API-initiated eviction differs from deleting a Pod directly. Which two things does it respect? Choose two.
89. 697. Which API version serves the Eviction subresource today?
90. 698. A Pod shows the status SchedulingGated and never reaches the scheduler. What must happen for it to proceed?
91. 699. A controller wants to pull an already-created Pod back out of the scheduling queue by adding a scheduling gate. What does the API allow?
92. 700. A RuntimeClass declares an overhead of 120Mi memory, and a Pod using it requests 256Mi across its containers. How much memory does the scheduler require on the node?
93. 814. A StorageClass leaves volumeBindingMode unset. When is a volume provisioned for a new claim?
94. 815. In a multi-zone cluster, Pods keep failing to start because their volume is in a different zone. Which StorageClass setting fixes this?
95. 822. Which two statements about local volumes are correct? Choose two.
96. 833. A cluster has CSIStorageCapacity objects but the scheduler still places Pods on nodes with no room. What is likely unset?
97. 834. A Pod requiring a new attached volume stays Pending on an otherwise idle node with plenty of CPU and memory. What limit could explain it?
98. 852. A Pod has been Pending for ten minutes. What does that state tell you, and where is the reason recorded?
99. 853. A Deployment using hostPort is scaled to 8 replicas on a 5-node cluster, and three Pods stay Pending. Why?
100. 871. A node goes unreachable. kubectl describe pod on one of its Pods shows a toleration for node.kubernetes.io/unreachable with tolerationSeconds 300. What does that govern?
101. 872. On a four-node cluster where each node has one CPU, a Pod requesting 1000m stays Pending on every node. What is the likely explanation?
102. 909. Why do PodDisruptionBudgets take effect during a kubectl drain?
103. 911. A drain refuses to proceed because of a Pod created directly with kubectl run and owned by no controller. Which flag allows it?
104. 913. An operator adds --disable-eviction to a drain to get past a blocking PodDisruptionBudget. What is the consequence?
105. 978. A node is uncordoned after maintenance. What happens to the Pods that were drained off it?
106. 995. During a graceful node shutdown, why can a Pod tolerating node.kubernetes.io/not-ready:NoSchedule still not start there?
107. 1000. A node configures shutdownGracePeriodByPodPriority with bands at 100000, 1000 and 0, but no Pod has a priority in the highest band. What happens at shutdown?