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ProbeDNS

About ProbeDNS

ProbeDNS is a free set of DNS, email deliverability, SSL, and network diagnostic tools. It is built and maintained by a hosting technical support engineer who uses tools like these every day and got tired of the ones that hide the useful part behind a signup form.

How the tools work

Every result comes from a live query made when you press the button. There is no cached marketing data and no simulated output anywhere on this site.

  • DNS lookups use the server’s system resolver through Node’s dns module. Record types that a stub resolver cannot request (DNSKEY, DS, TLSA, HTTPS) are queried over DNS-over-HTTPS.
  • The propagation checker opens a separate resolver per server and queries all 85 of them in parallel, then reports each one’s answer and response time individually.
  • Email checks read the same TXT records a receiving mail server reads, and parse them against the relevant RFCs (7208 for SPF, 6376 for DKIM, 7489 for DMARC).
  • SSL checks open a real TLS connection and inspect the certificate chain the server actually presents.
  • Browser utilities under /utilities run entirely in your browser. Passwords, hashes, and tokens you paste there are never sent to us.

Rules we hold ourselves to

  • No fabricated results. If a check cannot determine something, it says so rather than guessing.
  • No unverifiable claims. The site says 85 resolvers because the roster holds exactly 85 unique addresses, every one of which we verified answers real queries from our server. Resolvers that stopped serving the public were removed rather than left in to inflate the number.
  • No account required, and no storage of the domains you look up beyond short-lived caching.
  • Ads, where present, are kept away from the tool controls and never trigger layout shift.

Limits worth knowing

Queries are rate-limited per IP to keep the service available. Some checks depend on third-party systems (WHOIS registries, public blocklists, RIPEstat) that impose their own limits and can be slow or briefly unavailable — the tools report that honestly instead of pretending to have an answer.

Contact

Corrections and bug reports are genuinely welcome — especially if a tool returns something you can prove is wrong. Reach us at [email protected] or through the contact page.