Bulk CNAME lookup: the alias chain of up to 500 hostnames, with dangling CNAMEs flagged
In short: Paste hostnames and follow each one's CNAME chain to the final target and its addresses, with dangling CNAMEs (an alias to a name that doesn't resolve) flagged. Limit: Dangling means the target doesn't resolve now. It doesn't test whether the target can be claimed by someone else.
A bulk CNAME lookup follows the CNAME chain of many hostnames at once. Paste up to 100 hostnames, or 500 after a free Google sign-in, and each row shows every alias hop, the final target, the addresses it resolves to, and a dangling flag when the CNAME points at a name that doesn't resolve, a common cause of broken tracking links. DNS only, with a CSV.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
Sample result
track.acme.example is a CNAME to a name that no longer resolves: dangling.
- Hostname
- track.acme.example
- CNAME
- old-host.example.net
- Addresses
- none
What this means for you
A dangling CNAME breaks every link that uses the hostname. Remove it or point it at a live target.
- Every CNAME hop, up to eight
- Final target and its addresses
- Dangling CNAMEs and loops flagged
- CSV of every chain
- CNAME
- Tracking domain
- Dangling
By SimpleVerifier Team · Last updated
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Setting up tracking domains for a cold email campaign?
- A working tracking CNAME keeps links clickable; a clean list keeps the campaign out of spam. Upload the recipient list at /verify to remove addresses that would bounce.
- The first 100 email checks are free with a Google sign-in, no card. To check a tracking domain against the exact target Instantly, Smartlead, lemlist or Apollo expects, use the tracking domain checker.
How do I look up the CNAME records of many hostnames?
- Paste hostnames, one per line, such as
track.acme.comorwww.acme.com, up to 100 a run, or 500 after a free Google sign-in. URLs work too; the hostname is taken from each. - Press Look up CNAMEs. Each hostname's CNAME is followed hop by hop, up to eight, then the final name's A and AAAA records are read, 25 hostnames a request. DNS only.
- Read each row: Alias (a CNAME that resolves), Dangling (a CNAME whose target doesn't resolve), No CNAME (the name has its own addresses), Doesn't exist, or Loop.
- Filter to dangling or missing names and download the CSV with the full chain, the final target and the addresses.
Example
- You enter
- Three hostnames:
www.acme.example(CNAME to acme.example),track.acme.example(CNAME to a removed host) andacme.example. - You get
- www.acme.example: Alias, one hop to acme.example and its addresses. track.acme.example: Dangling, the target doesn't resolve. acme.example: No CNAME, it has its own A records. Download the CSV.
- Limits
- Up to 100 a run without an account and 500 when signed in with Google, counted over a minute. 25 hostnames a request; DNS only.
What does a CNAME lookup show?
A CNAME record makes one name an alias of another: track.acme.com CNAME prox.itrackly.com tells resolvers to look up the second name instead, as defined in RFC 1034. The target can itself be a CNAME, so a lookup follows the chain until a name with its own A or AAAA records.
For every hostname you paste, this tool records each hop, the final target and the IPv4 and IPv6 addresses it resolves to. A name with no CNAME but its own addresses shows No CNAME: a plain A record, or a CNAME your DNS host flattens or proxies, as Cloudflare does when the orange cloud is on.
What is a dangling CNAME?
A CNAME whose target doesn't resolve: the record still says shop.acme.com is an alias of acme.myshop-host.example, but that name no longer exists, usually because the service was cancelled and the DNS record was left behind. Anything that uses the hostname fails, and a tracking domain left dangling breaks every tracked link in the emails already sent.
On some hosting and cloud services, whoever claims the abandoned target name next can serve content on your hostname, which MDN describes as a subdomain takeover. Delete dangling CNAMEs you no longer use, or point them at a live target.
Why use a bulk CNAME lookup for cold email?
Teams that send from many domains set up a custom tracking domain on each, and it's easy for one to be missing or mistyped. Paste every tracking hostname at once and check each points at your sending tool's target, and that none is dangling or doesn't exist.
For one hostname with an HTTPS test and a check against the target your sending tool expects, use the single CNAME lookup. For every record type on many names, use the bulk DNS lookup.
Can a CNAME sit on the root domain?
No. RFC 1034 says a name with a CNAME can have no other records, and the root domain always has SOA and NS records, so acme.com itself can't be a CNAME. Some DNS hosts offer an ALIAS or flattened record that behaves like one; it shows here as No CNAME, with the addresses it returns.
If you type the full hostname into a DNS host's name field, many hosts add the domain again, creating track.acme.com.acme.com. When a hostname shows Doesn't exist, check the record wasn't created under that doubled name.
Which CNAME tool should I use?
| Bulk CNAME lookup | CNAME lookup | Tracking domain checker | |
|---|---|---|---|
| Hostnames per run | 100, or 500 signed in | One | Up to 10 sending domains |
| Full chain and addresses | Yes | Yes | Yes |
| Dangling CNAME flag | Yes | No | No |
| HTTPS and expected-target test | No | Yes | Yes, plus blocklists |
Who uses this tool, and for what?
- Cold emailers
- Check the custom tracking domain on every sending domain in one run, and catch the ones that are missing or dangling.
- Security teams
- Find dangling CNAMEs across a company's subdomains before someone else claims the target.
- Agencies
- Audit client subdomains pointing at Shopify, HubSpot or a landing page builder after a contract ends.
- Email admins
- Confirm DKIM and tracking CNAMEs delegated to a sending platform resolve after a DNS move.
What can’t this tool tell you?
- Dangling means the target doesn't resolve now. It doesn't test whether the target can be claimed by someone else.
- A CNAME your DNS host proxies or flattens shows as No CNAME, because public DNS returns addresses instead.
- It follows up to eight hops; longer chains are cut off and marked.
- DNS only: no HTTPS or page check on the hostnames.
- Up to 100 hostnames a run without an account, 500 signed in.
Common questions
- How do I look up CNAME records in bulk?
- Paste the hostnames into a bulk CNAME lookup like this one. Each row shows the CNAME chain, the final target and its addresses, with a CSV download.
- Is this bulk CNAME lookup free?
- Yes. Up to 100 hostnames a run without an account, and up to 500 a run when you sign in with Google, with no card.
- What does Dangling mean?
- The hostname has a CNAME, but the target it points to doesn't resolve to any address. Anything using the hostname fails until the record is fixed or removed.
- Why does my CNAME show No CNAME?
- The name answers with its own addresses. Either it's an A record, or your DNS host flattens or proxies the CNAME, as Cloudflare does with proxying on.
- Does it send anything to the hostnames?
- No. It only reads public DNS records. Nothing is requested from the hosts themselves.
- Can I check my custom tracking domains with it?
- Yes. Paste every tracking hostname and check each one's target. To compare against the exact target your sending tool expects, with an HTTPS test, use the tracking domain checker.
Sources
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product does.
- Upload the cleaned file as it is: CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.