What is the difference between DNS and WHOIS?
DNS records describe where internet services should send traffic for a domain. Registration information describes the domain’s registry or registrar, published dates and status. They answer different questions, so a DNS address alone does not identify a website owner.
Which DNS records should I check?
A records identify IPv4 addresses; AAAA records identify IPv6 addresses. MX records describe mail routing, NS records describe nameservers and TXT records can carry verification or email-policy values. CNAME records describe aliases. The common-records option checks these separately, instead of assuming one “ANY” response contains everything.
Why does the tool use RDAP registration data?
RDAP is the modern successor to traditional WHOIS for generic top-level domain registration data. This tool displays selected registry details for .com and .net where available. Other extensions include an official lookup link; .uk links to Nominet instead of republishing restricted registration information. Personal details may be withheld.
Does “not found” mean a domain is available to buy?
No. A provider error, unsupported extension, subdomain query or limited public response can all leave information unavailable. Check with the relevant registry or registrar before drawing a conclusion. For registration information, try the registered domain rather than a hostname such as www.
Why can DNS results differ from my computer?
This tool queries Google Public DNS from the website’s server. Your provider or device may use a different resolver or cached result. TTL is the lifetime reported in the DNS answer, not a promise that all caches will update at the same moment.
Sources: Google’s DNS query documentation, ICANN’s RDAP transition, and Nominet’s registration-data terms.