DNS Checker
The DNS Checker looks up all DNS records for any domain and attempts to discover subdomains — free and without any account.
How to use it
- Enter a domain name (e.g.
example.com— nohttps://needed) - Click Check
- Browse the results grouped by record type
Record types
| Type | Description |
|---|---|
| A | IPv4 address the domain points to |
| AAAA | IPv6 address |
| MX | Mail exchange servers (with priority) |
| TXT | Text records — includes SPF, DKIM, DMARC, site verification tokens |
| NS | Authoritative name servers |
| CNAME | Canonical name alias |
| SOA | Start of Authority — zone serial, refresh intervals |
Email authentication records
The tool highlights the three key email authentication records:
SPF (TXT record)
Specifies which servers are authorized to send email for the domain.
v=spf1 include:_spf.google.com ~allDKIM (TXT record at selector._domainkey.domain)
A cryptographic signature that verifies the email was not tampered with in transit.
DMARC (TXT record at _dmarc.domain)
Defines what to do with emails that fail SPF or DKIM checks (none, quarantine, or reject).
v=DMARC1; p=quarantine; rua=mailto:[email protected]Subdomain discovery
In addition to standard DNS queries, the tool attempts to enumerate subdomains by testing a list of common prefixes (www, mail, api, dev, staging, etc.).
This is a passive discovery technique using DNS resolution — it does not perform any active scanning or brute-force. Only publicly resolvable subdomains will appear.
Tips
- Propagation delays — DNS changes can take up to 48 hours to propagate globally. If you just made a change and don't see it yet, wait and check again.
- TTL — The Time To Live value (in seconds) tells resolvers how long to cache a record. Lower TTL = faster propagation when you make changes.
- Missing MX records — A domain without MX records cannot receive email.