Google Domains is not project based. Domains are managed by the identity of the domain owner.
Google Cloud Domains is in preview and is project based. At this time, there is no method to move a registered domain from one project to another. You can export the domain to Google Domains. Note: The DNS servers for a domain can be located in any project and do not need to be in the same project as Google Cloud Domains. Before exporting the domain, check to see if your domain is already being managed by Google Domains here. You will need to be using the same identity that owns the registered domain. If the domain appears, go to the other project, create the DNS servers and then enter the servers into Google Domains on the DNS tab under Name Servers. You can also change the DNS servers while in Google Cloud Domains. Select "EDIT DNS DETAILS" at the top of the Google Cloud Domains console window.
If you mean that you created the DNS server in one project and you need to move the DNS server to another project then follow these steps. Create a new DNS server in the desired project, duplicate the DNS server resource records and then update the DNS server entries in Google Domains. Wait at least 24 hours and then delete the old DNS server.
If you mean that your registered your domain under the wrong Google Account (email identity), then you can transfer the domain to the desired Google Account. Login to Google Domains with the account that you own the domain. In the interface follow the Transfer a domain out section. Get the authorization code. In another browser window, login with the desired account and transfer in the domain using the transfer authorization code.
Answer from John Hanley on Stack OverflowHas anyone here gone through the process of transferring a domain from Google Domains to Cloud Domains? I am looking to transfer my domains to GCP but am concerned about downtime and could not find information about TXT and A records being preserved in the transfer (I am slightly paranoid) Also, any word yet on Cloud Domains being affected by the Squarespace sale...?
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Google Domains is not project based. Domains are managed by the identity of the domain owner.
Google Cloud Domains is in preview and is project based. At this time, there is no method to move a registered domain from one project to another. You can export the domain to Google Domains. Note: The DNS servers for a domain can be located in any project and do not need to be in the same project as Google Cloud Domains. Before exporting the domain, check to see if your domain is already being managed by Google Domains here. You will need to be using the same identity that owns the registered domain. If the domain appears, go to the other project, create the DNS servers and then enter the servers into Google Domains on the DNS tab under Name Servers. You can also change the DNS servers while in Google Cloud Domains. Select "EDIT DNS DETAILS" at the top of the Google Cloud Domains console window.
If you mean that you created the DNS server in one project and you need to move the DNS server to another project then follow these steps. Create a new DNS server in the desired project, duplicate the DNS server resource records and then update the DNS server entries in Google Domains. Wait at least 24 hours and then delete the old DNS server.
If you mean that your registered your domain under the wrong Google Account (email identity), then you can transfer the domain to the desired Google Account. Login to Google Domains with the account that you own the domain. In the interface follow the Transfer a domain out section. Get the authorization code. In another browser window, login with the desired account and transfer in the domain using the transfer authorization code.
I just transfered a domain from one project to another one.
I exported the domain from the original project and then I just imported it on the new one.
You can see both options in the imaged I attached.