Node selectors for simple scheduling in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a node selector in Kubernetes?

A node selector is a simple way to tell Kubernetes to schedule a pod only on nodes that have specific labels. It helps control where pods run.

beginner

How do you specify a node selector in a pod's YAML file?

You add a nodeSelector field under spec with key-value pairs matching node labels. For example:<br>

spec:
  nodeSelector:
    disktype: ssd

beginner

What happens if no nodes match the node selector labels?

The pod will stay in a pending state and will not be scheduled until a matching node becomes available.

intermediate

Can a node selector use multiple labels?

Yes, you can specify multiple key-value pairs in nodeSelector. The pod will only schedule on nodes that have all those labels.

beginner

How do you label a node in Kubernetes?

Use the command: kubectl label nodes <node-name> key=value. This adds a label to the node that can be matched by node selectors.

What does a node selector do in Kubernetes?

A Updates node software

B Automatically scales nodes

C Deletes pods on nodes

D Schedules pods only on nodes with matching labels

A node selector restricts pod scheduling to nodes with specific labels.

Where do you specify the node selector in a pod YAML file?

A Under metadata.labels

B Under spec.nodeSelector

C Under spec.containers

D Under status.conditions

The node selector is specified under the pod's spec.nodeSelector field.

What happens if no nodes match the node selector labels?

A Pod is deleted automatically

B Pod is scheduled on any node

C Pod stays pending and is not scheduled

D Pod runs on the master node

If no nodes match, the pod remains pending until a suitable node is available.

How do you add a label to a node?

A kubectl label nodes <node-name> key=value

B kubectl add label <node-name> key=value

C kubectl set label pod <pod-name> key=value

D kubectl node label add key=value

The correct command to label a node is kubectl label nodes key=value.

Can a node selector require multiple labels?

A Yes, all labels must match on the node

B No, only one label is allowed

C Yes, but only one label needs to match

D No, node selectors do not use labels

A node selector can specify multiple labels, and all must match on the node.

Explain how node selectors control pod scheduling in Kubernetes.

Think about how pods find the right nodes to run on.

Describe the steps to label a node and use that label to schedule a pod.

Start from labeling the node, then tell the pod to use that label.