CNAME Lookup Alias
A CNAME lookup shows whether a hostname is an alias for another name. Enter a hostname to see its CNAME record, each further hop in the chain, the final target, and the IP addresses that target resolves to.
How to read CNAME lookup results
The result is a numbered chain. Step 1 is the hostname you entered and the name its CNAME record points to. If that target is itself an alias, the tool follows it and adds another step, up to ten hops. The last entry is the final target: the first name in the chain that is not an alias, shown with the A and AAAA records it returns.
If the hostname has no CNAME record, the tool says so and shows the address records the name answers with directly. That is the normal result for a bare domain such as example.com.
What a CNAME tells you
The target name usually identifies the service behind a hostname, because providers ask customers to point a CNAME at a name inside the provider's own domain:
- Hosting and CDN. Targets inside a CDN or hosting platform's domain show where a website is served from.
- SaaS on a custom domain. Help centers, status pages, storefronts and marketing pages on a company subdomain are typically CNAMEs to the vendor.
- Email services. DKIM selectors and bounce domains are often CNAMEs to the email platform, which lets the platform rotate keys without the customer editing DNS.
- Certificate validation. Names beginning with an underscore that point to a certificate authority's domain are used to prove control of the domain when a certificate is issued.
Common CNAME problems
- CNAME at the zone apex. The bare domain must carry SOA and NS records, and a CNAME cannot coexist with other records. DNS providers work around this with ALIAS or ANAME records or with CNAME flattening, all of which appear as ordinary A records from outside.
- CNAME next to other records. A hostname with a CNAME cannot also have MX or TXT records. Putting a CNAME on a name that needs to receive mail breaks delivery.
- Target that no longer resolves. When a service is cancelled but the CNAME is left in place, the alias points at a name that does not answer. The tool flags a final target with no address. These leftover records are worth removing; our article on taking inventory of dangling CNAMEs explains why.
- Loops and long chains. A chain that returns to a name it already passed never resolves. A chain of four or more hops works but slows every first visit and fails if any link breaks.
- MX or NS pointing at an alias. Mail exchanger and nameserver records should point to names with their own address records, not to CNAMEs.
For the record format and more examples, see the CNAME record guide. To look for aliases across all of a domain's known subdomains at once, use the CNAME option in the DNS Record Lookup.
Frequently asked questions
What is a CNAME record?
A CNAME (canonical name) record makes a hostname an alias of another hostname. A resolver that asks for the alias is told to look up the target name instead, so the alias always follows the target's addresses.
Why does my root domain have no CNAME?
The DNS standard does not allow a CNAME to share a name with any other record, and the root of a zone must hold SOA and NS records. Providers offer ALIAS, ANAME or CNAME flattening to get the same effect; from outside, those appear as normal A and AAAA records.
What is the difference between a CNAME and an A record?
An A record maps a name directly to an IPv4 address. A CNAME maps a name to another name, and the address is found by a second lookup on that target. Use a CNAME when a provider controls the address and may change it.
Can a CNAME point to another CNAME?
Yes. Chains are valid and common with CDNs. Each hop costs an extra lookup, though, and resolvers stop following after a limited number of hops, so short chains are more reliable.
What does it mean when the CNAME target does not resolve?
The alias points to a name that currently has no address records. Usually the service it pointed to was removed and the DNS record was left behind. The hostname will not load, and the record should be deleted or repointed.
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