Merge pull request #20715 from bridgetkromhout/cluster-cidr-clarification

Clarification of formatting for IPv4/IPv6 CIDRs

Author: k8s-ci-robot

content/en/docs/concepts/services-networking/dual-stack.md

@@ -49,15 +49,22 @@ To enable IPv4/IPv6 dual-stack, enable the `IPv6DualStack` [feature gate](/docs/
       * `--feature-gates="IPv6DualStack=true"`
    * kube-controller-manager:
       * `--feature-gates="IPv6DualStack=true"`
-      * `--cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR>` eg. `--cluster-cidr=10.244.0.0/16,fc00::/48`
-      * `--service-cluster-ip-range=<IPv4 CIDR>,<IPv6 CIDR>` eg. `--service-cluster-ip-range=10.0.0.0/16,fd00::/108`
+      * `--cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR>`
+      * `--service-cluster-ip-range=<IPv4 CIDR>,<IPv6 CIDR>`
       * `--node-cidr-mask-size-ipv4|--node-cidr-mask-size-ipv6` defaults to /24 for IPv4 and /64 for IPv6
    * kubelet:
       * `--feature-gates="IPv6DualStack=true"`
    * kube-proxy:
       * `--cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR>`
       * `--feature-gates="IPv6DualStack=true"`
 
+{{< note >}}
+An example of an IPv4 CIDR: `10.244.0.0/16` (though you would supply your own address range)
+
+An example of an IPv6 CIDR: `fdXY:IJKL:MNOP:15::/64` (this shows the format but is not a valid address - see [RFC 4193](https://tools.ietf.org/html/rfc4193))
+
+{{< /note >}}
+
 ## Services
 
 If your cluster has IPv4/IPv6 dual-stack networking enabled, you can create {{< glossary_tooltip text="Services" term_id="service" >}} with either an IPv4 or an IPv6 address. You can choose the address family for the Service's cluster IP by setting a field, `.spec.ipFamily`, on that Service.