* 2. IPv4: api-server will assign an IP from a `service-cluster-ip-range` that is `ipv4` (either the primary or the secondary, according to how they were configured).
    * 2. IPv6: api-server will assign an IP from a `service-cluster-ip-range` that is `ipv6` (either the primary or the secondary, according to how they were configured).
    * Notes (v1.16):
    * 1. IPVS is the only proxy supported (as of v1.16 ) by Dualstack.

- 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...

      - [Multi-platform](#multi-platform)
      - [Cloud Providers](#cloud-providers)
    - [Network](#network)
      - [network-policy](#network-policy)
      - [kube-proxy ipvs mode](#kube-proxy-ipvs-mode)
    - [API Machinery](#api-machinery)
      - [kube-apiserver](#kube-apiserver)
      - [Dynamic Admission Control](#dynamic-admission-control)

		if ipV4s[i].IsLoopback() {
			return false
		}
		if ipV4s[j].IsLoopback() {
			return true
		}
		return []byte(ipV4s[i].To4())[3] > []byte(ipV4s[j].To4())[3]
	})

	var ips []string
	for _, ip := range ipV4s {
		ips = append(ips, ip.String())
	}

	return append(nonIPs, ips...)
}

func getConsoleEndpoints() (consoleEndpoints []string) {

- Kube-proxy no longer falls back from ipvs mode to iptables mode if you ask it to do ipvs but the system is not correctly configured. Instead, it will just exit with an error. ([#111806](https://github.com/kubernetes/kubernetes/pull/111806), [@danwinship](https://github.com/danwinship)) [SIG Network]

 *   <dt>An IPv6 "IPv4 mapped" address, {@code "::ffff:192.168.0.1"}.
 *   <dd>{@code 00 00 00 00 00 00 00 00 00 00 ff ff c0 a8 00 01}
 * </dl>
 *
 * <p>A few notes about IPv6 "IPv4 mapped" addresses and their observed use in Java.
 *
 * <p>"IPv4 mapped" addresses were originally a representation of IPv4 addresses for use on an IPv6
 * socket that could receive both IPv4 and IPv6 connections (by disabling the {@code IPV6_V6ONLY}

    }

    @Test
    void testAddIPAddresses() throws Exception {
        InetAddress ipv4 = InetAddress.getByName("192.168.1.100");
        InetAddress ipv6 = InetAddress.getByName("2001:db8::1");

        notification.addNewIPAddress(ipv4);
        notification.addNewIPAddress(ipv6);
        notification.addOldIPAddress(ipv4);

        List<WitnessNotification.WitnessIPAddress> newAddresses = notification.getNewIPAddresses();

internal fun reorderForHappyEyeballs(addresses: List<InetAddress>): List<InetAddress> {
  if (addresses.size < 2) {
    return addresses
  }

  val (ipv6, ipv4) = addresses.partition { it is Inet6Address }

  return if (ipv6.isEmpty() || ipv4.isEmpty()) {
    addresses
  } else {
    interleave(ipv6, ipv4)
  }

    val request = Request(server1.url("/"))

    server1.enqueue(refusedStream)
    server2.enqueue(bodyResponse)

    dns[server1.hostName] = listOf(ipv6, ipv4)
    socketFactory[ipv6] = server1.socketAddress
    socketFactory[ipv4] = server2.socketAddress

    client =
      client
        .newBuilder()
        .fastFallback(false)
        .apply {
          retryOnConnectionFailure = false

# window size, and how much to save for an application buffer.
net.ipv4.tcp_adv_win_scale=1

# disable RFC2861 behavior
net.ipv4.tcp_slow_start_after_idle = 0

# Fix faulty network setups
net.ipv4.tcp_mtu_probing=1
net.ipv4.tcp_base_mss=1280

# Disable ipv6
net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1
net.ipv6.conf.lo.disable_ipv6=1

[bootloader]