About
About DNS Prism
A small set of free DNS tools: look up every common record type at once, compare what public resolvers answer, check reverse DNS, DNSSEC, nameservers and TXT records, and build zone files or subnet plans.
How it works
There is no DNS Prism server doing the lookups. When you press a button, the page builds a DNS query in the binary DNS wire format, encodes it and sends it from your browser to a public resolver using DNS-over-HTTPS (RFC 8484). The resolver’s binary answer is decoded in your browser, which is why you can see the raw response, the flags and the remaining TTLs exactly as the resolver sent them. The zone file generator and the subnet calculator make no network requests at all.
The resolvers
- Cloudflare (1.1.1.1, cloudflare-dns.com)
- Google Public DNS (8.8.8.8, dns.google)
- dnsforge.de (dnsforge.de), a resolver with servers in Germany whose default service blocks ads, trackers and malware
- DNS.SB (doh.dns.sb)
- Control D, its free unfiltered endpoint (freedns.controld.com/p0)
Cloudflare, Google, DNS.SB and Control D are anycast services: your browser is routed to the site of each that is nearest to you. dnsforge.de runs its servers in Germany. Comparing them therefore shows how five independent caches see a domain. It is useful after a change, but it is not a view from different countries, and DNS Prism does not claim to be one.
What it cannot do
Browsers cannot send classic DNS over UDP or TCP port 53, so DNS Prism cannot ask a domain’s authoritative nameservers directly, request zone transfers or test a specific nameserver. Every answer comes through one of the resolvers above, including its cache. The DNSSEC checker verifies DS digests itself but relies on the resolvers’ AD flag for signature validation.
Privacy in one paragraph
The names and addresses you look up go only to the resolvers listed above, sent by your browser. Nothing is stored on a server, there are no accounts, cookies or ads. The site uses Cloudflare Web Analytics, which counts page views without cookies or cross-site tracking and never receives what you type into the tools. The privacy page has the details.
Related sites
DNS Prism is one of a family of free single-purpose tool sites listed in the footer. For email authentication specifically (SPF, DKIM, DMARC and email header analysis), see MailTraceKit.