Registered hosts blurb say:
Register public hosts on your domain by IP address so they can be found without first resolving your domain in the DNS. Entries here are commonly called "glue records" and are needed when a domain's nameservers serve on one of its subdomains.
but Custom Records say:
Resource records define how your domain behaves. Common uses include pointing your domain at your web server or configuring email delivery for your domain.
If I want to register a public web host by IP address which one should I use?
Glue records are used to set up vanity DNS servers within your own domain, e.g.
example.com. If this is not what you are doing, do not attempt to create a glue record.
For all records you might want to put into the DNS, you’ll use normal resource records. Why Google calls these “custom” I have no idea.
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