A CNAME (Canonical Name) is a type of DNS record that defines an alias from one domain name to another. It’s a basic function used by millions of websites to create unique subdomains for different services, such as mail, search, etc. To allow for seamless interaction, the subdomains are trusted just like the primary domain. CNAME tracking abuses this fundamental mechanic and creates many more problems than unwelcome data collection
https://raw.githubusercontent.com/AdguardTeam/cname-trackers/master/combined_disguised_trackers_justdomains.txt
