How to add a CNAME to your Google Domains hosted domain:
Before you add a CNAME to your Google Domains, you may want to read our full guide about 1st Party Tracking.
to your Google Domains account.
Click on the domain that you’d like to update with a CNAME record.
Select the menu icon , followed by the DNS icon
Scroll down until you see the Custom resource records section.
In the Name or @ field, type in the subdomain you plan to use for your tracking.
In the Type drop-down menu, select CNAME.
In the TTL field, enter 1H.
In the Data field, paste in the unique CNAME value for your sub-domain.
Click the ADD button.
All set! You’ve successfully added your CNAME record to your Google Domains domain.
NOTE: CNAME records can take a few days to propagate. Once it's ready, you can ensure your entry works by using this article.