How to make the domain work with www?

Question

System administration

Added from the provider, where I rent a CNAME server from www.domain.com to domain.com, the dig domain.com CNAME command shows that there is a CNAME
But when I go to www.domain.com, the site does not work, writes

This site can't be reached
www.domain.com's server DNS address could not be found.

I did not change the settings, I checked apache2.conf and nginx.cong - everything is in order there, aliases are registered.
What needs to be done to make a domain with www?

Answer 1

DNS address could not be found

- The DNS address cannot be found, so it must be registered in the DNS.