- `-- 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.

- File content check for IPV4 is now enabled by default, and the check of IPV4 or IPV6 is done for `kubeadm init` or `kubeadm join` only in case the user intends to create a cluster to support that kind of IP address family ([#115420](https://github.com/kubernetes/kubernetes/pull/115420), [@chendave](http...

### (No, really, you MUST read this before you upgrade)

 
#### kube-proxy:
- Added kube-proxy flags `--ipvs-tcp-timeout`, `--ipvs-tcpfin-timeout`, `--ipvs-udp-timeout` to configure IPVS connection timeouts. ([#85517](https://github.com/kubernetes/kubernetes/pull/85517), [@andrewsykim](https://github.com/andrewsykim)) [SIG Cluster Lifecycle and Network]

- `kubelet` allows pods to use the `net.ipv4.tcp_fin_timeout`, “net.ipv4.tcp_keepalive_intvl”
  and “net.ipv4.tcp_keepalive_probes“ sysctl by default; Pod Security Admission
  allows this sysctl in `v1.29+` versions of the baseline and restricted policies. ([#121240](https://github.com/kubernetes/kubernetes/pull/121240), [@HirazawaUi](https://github.com/HirazawaUi))
- `kubelet` now allows pods to use the `net.ipv4.tcp_keepalive_time` sysctl by default

    * DualStack:
    * => IPv4 BackendPool name == clusterName
    * => IPv6 BackendPool name == <clusterName>-IPv6
    * This result into:
    * - clusters moving from IPv4 to duakstack will require no changes

This final piece completes the work needed to comply with Level 1 of the [SLSA security framework](https://slsa.dev/) (Supply-chain Levels for Software Artifacts).

### 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.

### IPv4/IPv6 run

  slightly stricter about what values will be accepted as IP addresses and network
  address ranges (“CIDR blocks”).
  
  In particular, octets within IPv4 addresses are not allowed to have any leading
  `0`s, and IPv4-mapped IPv6 values (e.g. `::ffff:192.168.0.1`) are forbidden.
  These sorts of values can potentially cause security problems when different

- PodLifecycleSleepAction is graduated to GA ([#128046](https://github.com/kubernetes/kubernetes/pull/128046), [@AxeZhan](https://github.com/AxeZhan)) [SIG Architecture, Node and Testing]
- Pods were allowed to use the `net.ipv4.tcp_rmem` and `net.ipv4.tcp_wmem` sysctl by default
  when the kernel version was 4.15 or higher. With the kernel 4.15 the sysctl became namespaced.