CNAME Record Lookup

What Is a CNAME Record?

A CNAME (Canonical Name) record is a DNS entry that aliases one domain name to another. Defined in RFC 1035 §3.3.1, CNAMEs let a single canonical name receive traffic from many alias hostnames — so www.example.com can point at example.com, or your status page at status.example.com can resolve to your monitoring provider's hostname.

When a resolver finds a CNAME, it follows the alias and resolves the target. The end answer is always the IP address (A or AAAA record) of the canonical name. CNAMEs are the foundation of every modern hosted service that hands you a hostname instead of an IP — Vercel, Netlify, Cloudflare Workers, AWS CloudFront, GitHub Pages, Stripe-hosted checkout pages, custom domains for SaaS apps. This tool queries CNAMEs directly via Cloudflare's DNS-over-HTTPS resolver — instant, no signup, no ads.

How CNAMEs Resolve

A CNAME lookup walks the alias chain. Suppose www.example.com is a CNAME for example.com, and example.com has an A record at 192.0.2.1:

Most resolvers (including Cloudflare's 1.1.1.1) follow this chain automatically and return both records in one response. Per RFC 1034 §3.6.2, the chain is bounded by an implementation-defined depth — most resolvers cap it around 8 hops to prevent loops.

Common CNAME Errors

CNAMEs are unusually strict compared to other DNS record types. The most common production failures:

• CNAME at the zone apex. Per RFC 2181 §10.1, the apex (e.g. example.com itself, not www.example.com) cannot be a CNAME because it must hold SOA and NS records. Use ALIAS, ANAME, or flattening (Cloudflare, DNSimple, Route 53) for apex pointers — never CNAME.
• Mixed CNAME with other records. A name that has a CNAME cannot also have A, AAAA, MX, TXT, or any other record type. Many DNS providers will accept the configuration but the result is undefined per RFC 1034 §3.6.2.
• Dangling CNAME target. The CNAME points at a host that no longer resolves (deactivated SaaS account, deleted CloudFront distribution, expired Heroku app). This is a common subdomain takeover vector — attackers register the abandoned target and serve content from your subdomain.
• CNAME loops. A points to B, B points to A. Resolvers bail out at the loop detection limit and return SERVFAIL.
• CNAME at MX or NS targets. Per RFC 2181 §10.3, the value of an MX or NS record must not be an alias. See the MX record lookup for verification.

CNAME vs A vs ALIAS vs ANAME

Each record type solves a different routing problem. Picking the wrong one is a top-three cause of DNS misconfiguration tickets at every CDN provider:

CNAMEs in Email Authentication

CNAMEs play a key role in three email auth flows:

• DKIM selector delegation. Many ESPs (Mailchimp, SendGrid, Postmark, Mailgun) ask you to publish a CNAME at selector._domainkey.yourdomain.com pointing at selector._domainkey.esp.com. The ESP rotates keys at the target without ever asking you to update your DNS. Verify with the DKIM checker.
• BIMI assertion records. Some BIMI deployments use a CNAME at default._bimi.yourdomain.com when delegating logo hosting to a vendor. See the BIMI checker.
• SES, Mailgun, and Postmark domain verification. All three commonly use CNAME chains for both the DKIM selector and the custom MAIL FROM (Return-Path) subdomain.

Command-Line CNAME Lookup

The terminal equivalents of this lookup:

• dig (Linux, macOS): dig CNAME www.example.com +short
• nslookup: nslookup -type=cname www.example.com
• host: host -t cname www.example.com
• PowerShell: Resolve-DnsName -Type CNAME www.example.com

FAQ

How do I check if a CNAME record exists?

Enter the hostname in the field above and click "Lookup." The tool queries Cloudflare's DoH resolver and returns the CNAME target plus every downstream record in the chain. From the command line, run dig CNAME hostname.example.com +short on Linux or macOS.

What is the purpose of a CNAME record?

CNAMEs let multiple hostnames share one canonical IP. A typical use case: you point www.example.com, app.example.com, and api.example.com all at example.com with CNAMEs, and only update the apex A record when you change hosting providers. Cloud platforms also rely on CNAMEs to give every customer a stable hostname while routing internally to whichever load balancer is live today.

How do I create a CNAME record?

In your DNS provider's control panel, add a new record with type "CNAME," name set to the alias hostname (e.g. www), and value set to the canonical target (e.g. example.com). Allow propagation up to the TTL — typically 5 minutes to 24 hours. Verify with this tool by entering the alias hostname.

What are the limitations of a CNAME record?

A CNAME cannot coexist with any other record at the same name (RFC 1034), cannot be used at the zone apex (RFC 2181 §10.1), and cannot be the target of an MX or NS record (RFC 2181 §10.3). For apex pointers, use an ALIAS or ANAME record at providers that support it (Cloudflare, DNSimple, Route 53), or use a forward A record.

Can I have multiple CNAME records for the same name?

No. A name may have at most one CNAME, and that CNAME excludes all other record types at that name. If you need multiple targets for one hostname, use multiple A records (round-robin) at the canonical target.

Why does my CNAME show as "no result"?

Most likely the name doesn't have a CNAME — only an A, AAAA, or other record type — or the CNAME target itself fails to resolve, in which case some resolvers return NXDOMAIN. Try the lookup at the apex domain and check whether ?type=A returns the expected IP using our DNS lookup tool.