I have created a subdomain and a CNAME record which points to the domain root. The subdomain
www.static.example.com is actually a copy of the entire website
www.example.com and it is supposed to act as an CDN and serve static content in order to improve speed. However, all of my content can be accessed via subdomain aswell, so Google has indexed it all and now I am dealing with duplicated content.
How could I deny access to crawlers for the subdomain baring in mind that I do not have different subfolder for subdomain, so I can't create a separate robots.txt file?