//
  // This field may hold a maximum of two entries (dual-stack families, in
  // either order).  These families must correspond to the values of the
  // clusterIPs field, if specified. Both clusterIPs and ipFamilies are
  // governed by the ipFamilyPolicy field.
  // +listType=atomic
  // +optional
  repeated string ipFamilies = 19;

  // IPFamilyPolicy represents the dual-stack-ness requested or required by

### 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.

<p>
Comparison operators compare two operands and yield an untyped boolean value.
</p>

<pre class="grammar">
==    equal
!=    not equal
&lt;     less
&lt;=    less or equal
&gt;     greater
&gt;=    greater or equal
</pre>

<p>
In any comparison, the first operand
must be <a href="#Assignability">assignable</a>
to the type of the second operand, or vice versa.

- `-- 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.

### 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.

- Kube-proxy: Added dual-stack IPv4/IPv6 support to the iptables proxier. ([#82462](https://github.com/kubernetes/kubernetes/pull/82462), [@vllry](https://github.com/vllry)) [SIG Network]

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

- [Topology Manager](https://github.com/kubernetes/enhancements/issues/693), a new Kubelet component, aims to co-ordinate resource assignment decisions to provide optimized resource allocations.
- [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.

- 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))

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