CNAME Checker
Look up a hostname's CNAME record and see exactly what it points to.
What is a CNAME record?
A CNAME (Canonical Name) record makes one hostname an alias for another. Instead of pointing at an IP address like an A record does, it points at another domain name, and DNS follows the chain to resolve the final address. Enter a hostname above and this tool shows exactly what it aliases to.
CNAMEs are common for subdomains that should follow a vendor's endpoint - a status page pointing at a hosting provider, a help center pointing at a support platform, or an email tracking subdomain pointing at your sequencer. The one hard rule: a root or apex domain (like example.com) cannot use a CNAME, only subdomains can.
Why apex domains can't use CNAME
The DNS spec forbids a CNAME on the apex because the apex already carries required records (SOA and NS) that a CNAME would conflict with. If you need apex-level aliasing, use an A/AAAA record instead, or a provider that offers CNAME flattening (Cloudflare, Route 53 alias records) which resolves the target and serves the resulting IP at the apex.
This is why your marketing site can live at www (a CNAME to your host) while the apex uses an A record or a flattened alias - and why an MX host, which also can't be a CNAME, must always resolve to a real A record.
CNAMEs and cold email tracking
Sequencers track opens and clicks by rewriting your links through a tracking domain. By default that's a shared vendor domain used by many senders, so you inherit whatever reputation the crowd has built. Pointing a branded tracking subdomain (like link.yourdomain.com) at the vendor via CNAME keeps those links on your own domain instead.
A custom tracking CNAME is a small but real deliverability win: the visible link matches your sending domain, which looks more trustworthy to both recipients and filters. Set it up once per sending domain and verify it resolves with the checker above.
Frequently asked questions
What is a CNAME record?
A CNAME record aliases one hostname to another domain name rather than an IP address. DNS follows the alias to resolve the final address. It's used for subdomains that should track a vendor's endpoint and for branded email tracking domains.
Why does my apex domain have no CNAME?
The DNS spec forbids CNAME records on a root/apex domain (like example.com) because it conflicts with the required SOA and NS records there. Only subdomains (like track.example.com) can use CNAME; the apex uses A/AAAA records or CNAME flattening instead.
Can an MX record point to a CNAME?
No. An MX host must resolve directly to an A record. Pointing it at a CNAME violates the mail RFCs and can cause delivery failures, so always give mail servers a real A record target.
Why does CNAME tracking matter for cold email?
A branded tracking CNAME keeps your click and open tracking links on your own domain rather than a shared vendor domain, which avoids inheriting another sender's reputation on those links and looks more trustworthy.
How long does a CNAME take to propagate?
Like other DNS records, 1 to 4 hours on a standard TTL, up to 48 hours for full global propagation. Lower the TTL before a planned change to speed it up.
Next steps
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