agent) that runs one, and only one, pod per node.
     * TLS and L7 support (Ingress API (Beta) in the Extensions API group): Kubernetes
is now easier to integrate into custom networking environments by supporting
TLS for secure communication and L7 http-based traffic routing.
     * Graceful Node Shutdown (aka drain) - The new “kubectl drain” command gracefully

 * service is a dynamic distributed service that allows hosts to resolve
 * names by broadcasting a query, directing queries to a server such as
 * Samba or WINS. NetBIOS is currently the primary networking layer for
 * providing name service, datagram service, and session service to the
 * Microsoft Windows platform. A NetBIOS name can be 15 characters long
 * and hosts usually registers several names on the network. From a

* Validate volume spec before returning azure mounter ([#37018](https://github.com/kubernetes/kubernetes/pull/37018), [@rootfs](https://github.com/rootfs))
* Networking test rewrite ([#31559](https://github.com/kubernetes/kubernetes/pull/31559), [@bprashanth](https://github.com/bprashanth))

* The deprecated kubelet --configure-cbr0 flag has been removed, and with that the "classic" networking mode as well.  If you depend on this mode, please investigate whether the other network plugins `kubenet` or `cni` meet your needs. ([#34906](https://github.com/kubernetes/kubernetes/pull/34906), [@luxas](https://github.com/luxas))

  - NetworkPolicy resources will no longer be served from `extensions/v1beta1` in v1.16. Migrate use to the `networking.k8s.io/v1` API, available since v1.8. Existing persisted data can be retrieved via the `networking.k8s.io/v1` API.

  - NetworkPolicy resources will no longer be served from `extensions/v1beta1` in v1.16. Migrate use to the `networking.k8s.io/v1` API, available since v1.8. Existing persisted data can be retrieved via the `networking.k8s.io/v1` API.

### 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.

* Stop 'kubectl drain' deleting pods with local storage. ([#26667](https://github.com/kubernetes/kubernetes/pull/26667), [@mml](https://github.com/mml))
* Networking e2es: Wait for all nodes to be schedulable in kubeproxy and networking tests ([#27008](https://github.com/kubernetes/kubernetes/pull/27008), [@zmerlynn](https://github.com/zmerlynn))

  - Ingress resources will no longer be served from `extensions/v1beta1` in v1.20. Migrate use to the `networking.k8s.io/v1beta1` API, available since v1.14. Existing persisted data can be retrieved via the `networking.k8s.io/v1beta1` API.

  
    A previous release built hyperkube using the debian-hyperkube-base@v1.0.0,
    which was updated to address a CVE in the CNI plugins.
    
    A side-effect of using this new image was that the networking packages
    (namely `iptables`) drifted from the versions used in the kube-proxy images.
  
    The following issues were filed on kube-proxy failures when using hyperkube: