How to Check if a Domain Has Wildcard DNS (For One Domain or Hundreds)

To check whether a domain has wildcard DNS, ask for subdomains that cannot exist and see whether they resolve. The bulk wildcard DNS checker generates two random names under each domain and asks for A, AAAA and CNAME records. If both resolve, a wildcard is answering, and the row shows what to. It takes up to 100 domains a run, or 500 after a free Google sign-in, and the output is a CSV.

The test is simple enough to do by hand for one domain, and the tool exists for the case where you have a list.

What a wildcard record is

A wildcard record is a DNS entry whose name starts with *, such as *.acme.com. RFC 4592 defines how it answers for any name below it that has no record of its own. So anything.acme.com resolves even though nobody created it. Sites use wildcards for per-customer subdomains, to catch mistyped hostnames, or by accident.

Why it matters

A wildcard makes every hostname look alive. Three consequences are worth knowing:

• A scan that guesses subdomains finds thousands of hits, almost all of them noise.
• A typo in a tracking or CNAME record still resolves instead of failing loudly, so the mistake can go unnoticed.
• A hostname resolving tells you nothing about whether a service is really set up there.

It is not a fault: many platforms depend on it. What you want to know is whether it is there on purpose, and what it points at.

Step 1: paste the domains

Paste domains, email addresses or URLs, one per line. The domain is taken from each, and a leading www. is dropped. Use up to 100 a run without an account, or 500 after a free Google sign-in.

Step 2: run the check

For each domain, two random names under it are queried for A, AAAA and CNAME records. The labels have the form sv- followed by 12 hex characters, so a real record at those names is practically impossible. The tool then looks up the domain's own SOA, name servers and addresses, 15 domains per request.

Step 3: read the result

Result	What it means
Wildcard	Both made-up names resolved. The row shows to what
No wildcard	The made-up names did not resolve
Doesn't exist	The domain itself is not in DNS
Lookup failed	The name servers did not answer properly. Try again later

For a Wildcard row, read the target. If it points at the domain's own host, it is probably deliberate. If it points at a third party, such as a parking page or a platform you do not remember using, look into who set it and why. The CSV lists the names queried, so you can repeat the lookup yourself with the bulk DNS lookup or, to follow a CNAME chain, the bulk CNAME lookup.

Doing it by hand for one domain

Make up a label you are certain you never created, such as zq7x3k-test, and look up zq7x3k-test.yourdomain.com with dig or any DNS lookup. If it returns an address or a CNAME, a wildcard exists. Do it twice with two different labels, as the tool does, so one coincidence does not mislead you.

Where the test can mislead

• Only A, AAAA and CNAME are tested. A wildcard that exists only for MX or TXT is not detected.
• Provider catch-alls. Some DNS providers answer unknown names with their own redirect or parking address for domains you have not configured. That can look like a wildcard. The answer in the row helps you tell the two apart.
• Two probes only. A zone that answers some made-up names and not others can be missed.
• Caching. Public DNS can serve cached answers for up to the record's TTL, so a change you just made may not show yet.

Where this fits in a domain audit

If you manage many domains, wildcard status belongs next to the other DNS facts you collect. Our guides on looking up a domain's TXT records, bulk DNS lookups for a list of domains and checking DNSSEC cover the neighbours. A wildcard is also worth knowing about before you buy or take over a domain, because it changes what a resolving subdomain proves.

For email, note that a wildcard on A or CNAME does not give you working mail. Mail routing depends on MX records, which this check does not test.

What this check cannot do

• It tests A, AAAA and CNAME only, not MX or TXT.
• A DNS provider's own catch-all can look like a wildcard.
• Two probes per domain can miss a partial wildcard.
• It cannot say whether a wildcard is deliberate. That needs the domain owner.
• The limit is 100 domains a run without an account and 500 signed in.

If the domains are your leads' companies

Once the domain list is sorted, check that you can reach the people. Upload the addresses on the verify page: the first 100 email checks are free with a Google sign-in, no card. Each comes back valid, risky or invalid with a reason, and nothing is sent to anyone on the list. For bigger or recurring lists, see bulk email verification, list cleaning and pricing.

Check your domains now

Paste them into the bulk wildcard DNS checker.