Wildcard DNS check
Asks the public resolvers for A, AAAA, TXT and MX of a random name under the domain and reports a wildcard (RFC 4592) when it answers, with a warning for a wildcard MX. The test name is new for every request, so no cached answer is reused.
Updated 2026-10-27
What this tool checks
The zone's SOA is looked up first, so a domain that does not exist is reported as such. Then A, AAAA, TXT and MX of the random name are asked through public resolvers:
- Any answer, even an empty one for another type, means a wildcard covers the name.
- The types that returned records are listed, so you see what the wildcard publishes.
- MX gets a warning of its own.
How to read the result
The table shows each record type with its response code and records. NXDOMAIN for all four means there is no wildcard at that level.
Limitations
- Only the level directly under the name is tested; a wildcard deeper in the zone (such as
*.dev.example.com) needs a check on that name.
Use it from code
API reference for Wildcard DNS check
curl -i "https://api.lookproof.dev/v1/dns/wildcard?domain=example.com"A request without payment is answered with 402 Payment Required and the exact price. See the API reference.
Limits
| Input | Domain |
|---|---|
| Deadline | 10 seconds |
| Freshness | Up to 5 minutes, never longer than the record TTL |
| Price | $0.01 per check |
Findings this tool can report
Wildcard records (2)
- Info
WILDCARD_FOUNDThe zone answers for names that do not exist: it has a wildcard. - Warning
WILDCARD_MXEvery made-up name under the domain accepts mail (wildcard MX).
Check (1)
- Warning
CHECK_QUERY_BUDGET_EXCEEDEDThe check stopped after reaching its DNS query limit.
DNS (3)
- Error
DNS_DOMAIN_NOT_FOUNDThe DNS resolver reported that the domain does not exist. - Warning
DNS_RESOLVER_FAILUREThe DNS resolver returned a server failure. - Warning
DNS_RESOLVER_TIMEOUTThe DNS resolver did not answer in time.
Frequently asked questions
How does the check find a wildcard?
It asks for A, AAAA, TXT and MX of a random name under the domain, such as lp-1a2b3c4d5e6f.example.com. Nobody creates such a name, so any answer comes from a wildcard record (RFC 4592): WILDCARD_FOUND.
Is a wildcard a problem?
Not by itself: catch-all web hosting uses one. But typing errors in host names then resolve instead of failing, and a wildcard MX accepts mail for every invented subdomain: WILDCARD_MX.
Why a new test name every time?
So no resolver can answer from its cache, and the result reflects the zone as it is now. The test name is shown in the result.