- When the cluster size is small and the scheduler doesn't get unscheduled Pods frequently, the scheduler doesn't try to reschedule Pods in some cases. ([#119784](https://github.com/kubernetes/kubernetes/pull/119784), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling and Testing]

## Dependencies

- If we set SelectPolicy MinPolicySelect on scaleUp behavior or scaleDown behavior,Horizontal Pod Autoscaler doesn't automatically scale the number of pods correctly ([#95647](https://github.com/kubernetes/kubernetes/pull/95647), [@JoshuaAndrew](https://github.com/JoshuaAndrew)) [SIG Apps and Autoscaling]

- The extension API server can now dynamically discover the requestheader CA certificate when the core API server doesn't use certificate based authentication for it's clients. ([#66394](https://github.com/kubernetes/kubernetes/pull/66394), [@rtripat](https://github.com/rtripat))

### SIG Autoscaling

    * Action required:
    * Anyone who generated server cert for admission webhooks need to regenerate the cert. Previously, when generating server cert for the admission webhook, the CN value doesn't matter. Now you must set it to the DNS name of the webhook service, i.e., `<service.Name>.<service.Namespace>.svc`.

- Reduce default NodeStatusReportFrequency to 5 minutes. With this change, periodic node status updates will be send every 5m if node status doesn't change (otherwise they are still send with 10s).

* Allows extension API server to dynamically discover the requestheader CA certificate when the core API server doesn't use certificate based authentication for it's clients ([#66394](https://github.com/kubernetes/kubernetes/pull/66394), [@rtripat](https://github.com/rtripat))

## Changelog since v1.26.0

## Known Issues

### The PreEnqueue extension point doesn't work for Pods going to activeQ through backoffQ

In v1.26.0, we've found the bug that the PreEnqueue extension point doesn't work for Pods going to activeQ through backoffQ. 
It doesn't affect any of the vanilla Kubernetes behavior, but, may break custom PreEnqueue plugins.

* Skip safe to detach check if node API object no longer exists ([#30737](https://github.com/kubernetes/kubernetes/pull/30737), [@saad-ali](https://github.com/saad-ali))
* Nodecontroller doesn't flip readiness on pods if kubeletVersion < 1.2.0 ([#30828](https://github.com/kubernetes/kubernetes/pull/30828), [@bprashanth](https://github.com/bprashanth))

* Allows extension API server to dynamically discover the requestheader CA certificate when the core API server doesn't use certificate based authentication for it's clients ([#66394](https://github.com/kubernetes/kubernetes/pull/66394), [@rtripat](https://github.com/rtripat))

* GCI: Update the command to get the image ([#24987](https://github.com/kubernetes/kubernetes/pull/24987), [@andyzheng0831](https://github.com/andyzheng0831))
* Validate deletion timestamp doesn't change on update ([#24839](https://github.com/kubernetes/kubernetes/pull/24839), [@liggitt](https://github.com/liggitt))