### IPv4/IPv6 run

IPv4/IPv6 dual-stack has been reimplemented for 1.20 to support dual-stack Services, based on user and community feedback. If your cluster has dual-stack enabled, you can create Services which can use IPv4, IPv6, or both, and you can change this setting for existing Services. Details are available in updated [IPv4/IPv6 dual-stack docs](https://docs.k8s.io/concepts/services-networking/dual-stack/), which cover the nuanced array of options.

- `-- kube-controller-manager`
  `--node-cidr-mask-size-ipv4 int32`     Default: 24. Mask size for IPv4 node-cidr in dual-stack cluster.
`--node-cidr-mask-size-ipv6 int32`     Default: 64. Mask size for IPv6 node-cidr in dual-stack cluster.

    These 2 flags can be used only for dual-stack clusters. For non dual-stack clusters, continue to use  `--node-cidr-mask-size` flag to configure the mask size.

- Kube-proxy: on dual-stack mode, if it is not able to get the IP Family of an endpoint, logs it with level InfoV(4) instead of Warning, avoiding flooding the logs for endpoints without addresses ([#88934](https://github.com/kubernetes/kubernetes/pull/88934), [@aojea](https://github.com/aojea)) [SIG Network]

### IPv4/IPv6 Dual-stack Networking graduates to GA

[IPv4/IPv6 dual-stack networking](https://github.com/kubernetes/enhancements/tree/master/keps/sig-network/563-dual-stack) graduates to GA.
Since 1.21, Kubernetes clusters are enabled to support dual-stack networking by default.
In 1.23, the `IPv6DualStack` feature gate is removed.
The use of dual-stack networking is not mandatory.

- [IPv4/IPv6 dual-stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack) enables the allocation of both IPv4 and IPv6 addresses to Pods and Services.

  // to SingleStack. Services can be "SingleStack" (a single IP family),
  // "PreferDualStack" (two IP families on dual-stack configured clusters or
  // a single IP family on single-stack clusters), or "RequireDualStack"
  // (two IP families on dual-stack configured clusters, otherwise fail). The
  // ipFamilies and clusterIPs fields depend on the value of this field. This

- Users might specify the `kubectl.kubernetes.io/default-container` annotation in a Pod to...

- The `CloudDualStackNodeIPs` feature is now `beta`, meaning that when using
  an external cloud provider that has been updated to support the feature,
  you can pass comma-separated dual-stack `--node-ips` to `kubelet` and have
  the cloud provider take both IPs into account. ([#120275](https://github.com/kubernetes/kubernetes/pull/120275), [@danwinship](https://github.com/danwinship))

- Kubeadm: update `CoreDNS` to 1.8.4. Grant `CoreDNS` permissions to "list" and "watch" `EndpointSlice` objects to accommodate dual-stack support. ([#102466](https://github.com/kubernetes/kubernetes/pull/102466), [@pacoxu](https://github.com/pacoxu))

- Graduated HorizontalPodAutoscaler support for per-container metrics to stable. ([#123482](https://github.com/kubernetes/kubernetes/pull/123482), [@sanposhiho](https://github.com/sanposhiho))