Is a CNAME to CNAME chain allowed?

Better Stack Team
Updated on November 23, 2023

No, a CNAME to CNAME chain is not allowed in DNS due to restrictions specified in DNS standards. In DNS (Domain Name System), a CNAME (Canonical Name) record is used to create an alias from one domain name to another, allowing a domain or subdomain to be an alias for another domain name.

The DNS standards prohibit creating a CNAME record that points to another CNAME record. When a CNAME record is used, it acts as an alias, redirecting the query to another domain name. Creating a chain of CNAME records (CNAME pointing to another CNAME, and so on) leads to several potential issues:

  1. Ambiguity and Indirection: A CNAME record is supposed to be the final resolution of a domain name to its canonical name. Creating a chain of CNAME records creates an endless loop of indirection, making it impossible to get to the final canonical name and resulting in ambiguous and circular references.
  2. Technical Restrictions: DNS standards don't allow a domain to have multiple CNAME records as they might conflict with other records and disrupt the proper functioning of the DNS resolution process.

To illustrate this point: If you set up a CNAME record pointing to another CNAME, it creates an endless loop where the resolution never reaches an actual endpoint, leading to issues and inconsistencies in DNS resolution.

In DNS, a domain name can have only one CNAME record associated with it. This restriction is to maintain the efficiency and predictability of the DNS resolution process and prevent conflicts or circular references that would hinder the accurate mapping of domain names to their respective canonical names.

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