aero
// 2LDs
airline.aero
airport.aero
// 2LDs (currently not accepting registration, seemingly never have)
// As of 2024-07, these are marked as reserved for potential 3LD
// registrations (clause 11 "allocated subdomains" in the 2006 TLD
// policy), but the relevant industry partners have not opened them up
// for registration. Current status can be determined from the TLD's
// policy document: 2LDs that are open for registration must list

  * A pod can specify its own Hostname and Subdomain via annotations (<code>pod.beta.kubernetes.io/hostname, pod.beta.kubernetes.io/subdomain)</code>. If the Subdomain matches the name of a [headless service](http://kubernetes.io/docs/user-guide/services/#headless-services) in the same namespace, a DNS A record is also created for the pod’s FQDN. More

        assertTrue(urlFilter.match("http://www.example.com/"));
        assertTrue(urlFilter.match("https://api.example.com/v1/users"));
        assertTrue(urlFilter.match("http://subdomain.example.com/page"));
        assertFalse(urlFilter.match("https://example.org/"));
        assertFalse(urlFilter.match("ftp://files.example.com/"));
    }

    /**

### kube-dns
* Adds support for configurable DNS stub domains and upstream nameservers.
  The following configuration options have been added to the `kube-system:kube-dns` ConfigMap:
  ```
  "stubDomains": {
    "acme.local": ["1.2.3.4"]
  },
  ```
  is a map of domain to list of nameservers for the domain. This is used
  to inject private DNS domains into the kube-dns namespace. In the above

   * Fix confusing logging when initialize server

   * Fix printf in cmd/kube-dns/app/server.go

   * Fix version on startup and `--version` flag

   * Support specifying port number for nameserver in stubDomains

#### kube-proxy
* Features:

  * ratelimit runs of iptables by sync-period flags ([#46266](https://github.com/kubernetes/kubernetes/pull/46266), [@thockin](https://github.com/thockin))

* Port-forward: use out and error streams instead of glog ([#17030](https://github.com/kubernetes/kubernetes/pull/17030), [@csrwng](https://github.com/csrwng))
* Promote Pod Hostname & Subdomain to fields (were annotations) ([#24362](https://github.com/kubernetes/kubernetes/pull/24362), [@ArtfulCoder](https://github.com/ArtfulCoder))

- Allowed setting the `hostnameOverride` field in `PodSpec` to specify any RFC 1123 DNS subdomain as the pod's hostname. The `HostnameOverride` feature gate was introduced to control enablement of this functionality. ([#132558](https://github.com/kubernetes/kubernetes/pull/132558), [@HirazawaUi](https://github.com/HirazawaUi)) [SIG API Machinery,...

### Feature

- Added `k8s-short-name` and `k8s-long-name` format validation tags to enforce DNS label and DNS subdomain compliance. ([#133894](https://github.com/kubernetes/kubernetes/pull/133894), [@lalitc375](https://github.com/lalitc375))

- Dynamic Resource Allocator (DRA): Enhanced validation for the ResourceClaimParametersReference and ResourceClassParametersReference with the following rules:
  
  1. `apiGroup`: If set, it must be a valid DNS subdomain (e.g. 'example.com').

* `StubDomains` and `Upstreamnameserver` which contains a service name will be omitted while translating to the equivalent CoreDNS config. ([#75969](https://github.com/kubernetes/kubernetes/pull/75969), [@rajansandeep](https://github.com/rajansandeep))