What is a CNAME record?

A CNAME (Canonical Name) record is a DNS record that maps one hostname to another. Instead of returning an IP address directly, it tells the resolver to look up the target hostname instead. The target is called the canonical name. CNAMEs are commonly used to point subdomains to hosting providers, CDNs, and SaaS platforms.

Can I use a CNAME at the root domain?

No. The DNS specification (RFC 1034) forbids placing a CNAME at the zone apex because the apex must also have SOA and NS records, and a CNAME cannot coexist with other record types. Some DNS providers offer non-standard ALIAS or ANAME records that accomplish the same thing, but standard CNAMEs won't work there.

What is a CNAME chain?

A CNAME chain happens when one CNAME points to another CNAME, which may point to yet another. Each link adds a DNS round-trip before the final A or AAAA record is reached. Most resolvers follow chains up to about 8 hops. Keep chains short to avoid unnecessary latency and potential resolution failures.

How is a CNAME different from an A record?

An A record maps a hostname directly to an IPv4 address. A CNAME maps a hostname to another hostname. The CNAME is an alias; the A record is the final destination. When a resolver encounters a CNAME, it must do at least one more lookup to find the A record at the end of the chain.

Can a CNAME point to another CNAME?

Yes. There is no hard rule against it, and resolvers will follow the chain. But every hop adds latency, and long chains increase the chance of a timeout or misconfiguration. Best practice is to CNAME directly to a hostname that has an A or AAAA record.

What happens if the CNAME target doesn't exist?

The resolver follows the CNAME to the target hostname and gets an NXDOMAIN response (non-existent domain). The client sees the lookup fail entirely. This is called a dangling CNAME. It causes downtime for the subdomain and can be a security risk if an attacker registers the abandoned target hostname.

Do CNAME records affect email?

Indirectly, yes. A CNAME record cannot coexist with an MX record on the same hostname. If you set up a CNAME on a name that mail servers reference for MX lookups, email delivery will break. DKIM selectors, on the other hand, are often set up as CNAMEs by design, since they only need to return a TXT record at the provider's hostname.

What is CNAME flattening?

CNAME flattening is a feature offered by some DNS providers (Cloudflare, Route 53) that resolves the CNAME chain on the server side and returns the final A/AAAA record directly. This allows CNAME-like behavior at the zone apex without violating the RFC. The client never sees the CNAME; it only sees the A record.

Yes. No signup, no rate limit for normal use, no paywall. Queries go through our edge function to a public DoH resolver. We don't log the domains you check.

Free CNAME Lookup — Alias Target + Chain Verification

GET STARTED

Quickstart Guide

Up and running in minutes

Help Center

400+ in-depth articles

API Documentation

REST reference for devs

COMPARE

Pricing

Plans that scale

Integrations

16 ESPs and CRMs

Enterprise

For high-volume teams

COMPANY

About

Mission and team

Blog

Deliverability essays

Contact

Get in touch

Pricing

Integrations Enterprise