CNAME Lookup

A CNAME lookup checks whether a hostname is an alias and shows the canonical hostname it points to. Use robtex.com to inspect CNAME records and follow alias chains alongside the rest of the domain's DNS data.

What CNAME records do

A canonical name (CNAME) record points one hostname at another hostname. It is commonly used forwww, customer subdomains, CDN hostnames, SaaS verification names, and hosted application aliases.

CNAME records do not point directly to IP addresses. The target hostname still needs A or AAAA records, and resolvers continue following the chain until they find address records or the lookup fails.

How to use it

Open an example CNAME lookup for www.example.com

Enter a hostname, not just the registered domain, when you want to check a specific alias such aswww.example.comorapp.example.com. The DNS lookup result shows the CNAME record when one exists, plus the target's related DNS records.

What to check

Confirm that the CNAME target is the hostname your provider expects, that it resolves correctly, and that it does not create a loop. If the hostname is used for a web service, also check the target's A, AAAA, HTTPS, and certificate configuration.

For migrations, compare the current CNAME with surrounding MX, NS, and TXT records. This helps separate web routing changes from mail routing, nameserver delegation, and domain verification records.

Use MX Lookup for mail routing, NS Lookup for delegation, and TXT Lookup for SPF, DKIM, DMARC, and verification records.

FAQ

What is a CNAME lookup?
A CNAME lookup checks a hostname for a canonical name record and shows the target hostname the alias points to.
Can a root domain have a CNAME record?
A zone apex normally cannot use a CNAME because it must also have SOA and NS records. Some DNS providers offer CNAME-like flattening, but that is provider behavior, not a standard apex CNAME.
Why does my CNAME still need A or AAAA records?
The CNAME target must eventually resolve to address records. A CNAME only creates an alias, it does not provide the final IP address by itself.
Can CNAME records affect email?
They can if you put a CNAME on a hostname used by mail-related records, but MX records themselves point to mail server hostnames. Use MX and TXT lookups to verify mail routing and authentication.
What causes a CNAME lookup to fail?
Common causes include a missing target, a loop, a typo in the target hostname, stale provider instructions, or nameservers that are not serving the expected zone.