How to set up a CNAME record for a domain so that it opens a third-party subdomain?

Question

Domain Name System

Is it necessary to
open the 111.site .com
subdomain on the site.ru domain Using a CNAME record, is it possible to do this without having access to editing the DNS of the 111.site .com subdomain ?
I set up a record for site.ru for the CNAME test:
site.ru CNAME 111.site.com - does not work, opens the main domain site. com
How this idea can be implemented, CNAME record is not required, IP can be used.

Answer 1

No way. This is not a dns problem at all.
To get 111.site.com you need to put "111.site.com" in the $http_host request header, and you have "site.ru" there.
site.com does not know about such a virtual host - and gives the host by default.