Multiple PTR records being returned for a Pod backed by multiple Services

[adrianmoisey]

What happened?

In the scenario where a Pod has multiple Services pointing at it, multiple PTR records are also created.

What did you expect to happen?

A single PTR record to be created.

How can we reproduce it (as minimally and precisely as possible)?

1. Create a Deployment with at least 1 replica in it
2. Create a service that matches the labels of that Deployment
3. Create a second service that matches the labels of that Deployment
4. Query the PTR record for the pod's IP address

Anything else we need to know?

This was discovered in trying to understand the behaviour in #124207
There is more context here: https://kubernetes.slack.com/archives/C09QYUH5W/p1713551070931899?thread_ts=1713088975.540039&cid=C09QYUH5W

Kubernetes version

$ kubectl version
Client Version: v1.30.0
Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
Server Version: v1.29.2```

</details>


### Cloud provider

<details>
Discovered using kind
Reproduced on GKE
</details>


### OS version

<details>

```console
# On Linux:
$ cat /etc/os-release
# paste output here
$ uname -a
# paste output here

# On Windows:
C:\> wmic os get Caption, Version, BuildNumber, OSArchitecture
# paste output here

Install tools

Container runtime (CRI) and version (if applicable)

Related plugins (CNI, CSI, ...) and versions (if applicable)

[k8s-ci-robot]

This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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[neolit123]

/sig network

[adrianmoisey]

Depends on coredns/coredns#6623

[thockin]

For bookkeeping I am going to close this, and let coredns/coredns#6623 be the final word. OK with that?

[adrianmoisey]

Works for me!

[adrianmoisey]

/close

[k8s-ci-robot]

@adrianmoisey: Closing this issue.

In response to this:

/close

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.