Setting up multiple reverse DNS entries is super simple in linux but I cannot find documentation on doing it in google cloud. I see how to add one, but not how to add several. The server hosts multiple domains and I need rDNS validation of all of them.
Technically you can setup Reverse DNS for multiple DNS entries to the same IP address. However, this is not recommended.
Google Cloud DNS will not help you with Reverse DNS. The IP addresses are owned by Google and Google needs to configure the settings for you in their system. At this time, you can only configure one PTR record per static public IP address.
Note: Only certain types of static public IP addresses are support. For example, an IP address attached to Compute Engine is supported. An IP address attached to a Google Load Balancer is not supported.
If I'm understanding what you want, you need to do something like this:
$gcloud compute instances update-access-config [INSTANCE_NAME] --public-ptr --public-ptr-domain [DOMAIN_NAME]
Take a look at this documentation.
NOTE: I'm editing my answer as I cannot comment on other user's answers.
The answer by John Hanley made me think about this scenario and do some consults and research.
My conclusions are:
- Using internal DNS you can only have one PTR record per IP address.
- You can create a PTR record in a Cloud DNS managed private zone that would override the Compute Engine internal DNS PTR record.
- GCE internal DNS creates these reverse zones
- You can override GCE internal DNS reverse zones and PTRs with Cloud DNS managed private zones.
- Technically, there's no limit on the number of entries a single PTR record can have.
- GCP does not allow you to create a public DNS zone for in-addr.arpa. So this might be of limited use.