Definition
A CNAME record creates an alias from one hostname to another. Instead of pointing to an IP address, it points to another hostname (the canonical name). Example: www.example.com CNAME example.com. CNAMEs cannot coexist with other records at the same hostname, and cannot be used at a zone apex (root domain) — use an A record or ALIAS/ANAME there instead.
Use the tool: DNS Lookup — check cname record for any domain.