Hi, @anthony, this depends on where you add the domain. It doesn’t matter where the domain is registered.
There are two ways to use a custom domain with a site at Netlify:
You can use either method with any domain. You can use mix and match for different domains on a single account but each domain can only use one of the two methods (Netlify DNS or external DNS).
If you add the custom domain only under Site Name > Settings > Domain management > Custom domains, then you are using external DNS.
If you add the domain under Team name > Domains, then you are using Netlify DNS. You still need to add the domain to the site (the instructions above) for sites using domains hosted with Netlify DNS. The required DNS records will be created automatically for any domains added to the site which are also using Netlify DNS.
If there are other questions about this, please let us know.