CNAME, or Canonical Name record, is a type of resource record in the Domain Name System (DNS) that specifies that one domain name is an alias of another canonical domain name. It's used to ensure that multiple services or websites can be accessed from one IP address, simplifying domain management and ensuring smoother user experience.

A CNAME lookup or CNAME check is the process of querying the DNS to find the canonical name associated with an alias name. This is done using a CNAME checker tool, which retrieves the CNAME record from the DNS. This process, also known as check CNAME or check CNAME records, is critical for diagnosing DNS-related issues and verifying that the CNAME records are correctly pointing to the right canonical name.

By correctly setting up and checking CNAME records, organizations can ensure that their web services are properly accessible, even if the underlying IP addresses change. This is particularly useful for load balancing, redirecting multiple domain names to a single domain, or providing separate hosting services for different parts of a website. In essence, whether you call it a CNAME lookup, CNAME check, or CNAME checker, it's an indispensable tool in the DNS management toolkit.