Before this message on domains in the Domain Management section, I had followed all the instructions mentioned by Netlify. My domain provider doesn’t support ALIAS, so I just point the “www” subdomain to Netlify’s subdomain. Also, when I wanted to set www as a primary domain, this message appears: We're provisioning a certificate for your site; you cannot change custom domains until that process completes.
After a while, the state became “Awaiting Netlify DNS” without any change.
Thanks for reaching out and welcome to Netlify’s Support Forums!
Looking at the site, I see that the domain is setup for a Netlify DNS Zone, however, the Netlify name servers mentioned here are not configured, only a2hosting.com name servers are configured.
This makes the DNS Zone inactive which can cause issues with provisioning an SSL Certificate. This is mentioned, along with the fix, in this Support Guide:
If you’re not planning on using the DNS Zone we recommend deleting it here.
For external DNS, we recommend pointing the apex domain’s A Record to 75.2.60.5. For the www subdomain we recommend pointing a CNAME Record to royalphonecenter.netlify.app.