Free DNS, Email and IP Tools
Everything here answers from live data. DNS queries go out to public resolvers when you press the button, and the calculators run right in your browser. There is nothing to install and no account to create.
Use the DNS tools to see where a domain points and which servers handle its mail, the email checkers to find out why messages land in spam, and the network tools to plan subnets. Each page explains what the results mean and what usually goes wrong.
DNS tools
Look up any DNS record, trace aliases, and see how long a change will take.
DNS LookupCheck A, AAAA, MX, NS, TXT, CNAME, SOA and CAA records for any domain.Open tool NSLookup OnlineRun an nslookup from your browser and learn the command options.Open tool MX LookupSee which mail servers receive email for a domain, in priority order.Open tool TXT Record LookupView SPF, DKIM, DMARC and verification text records, labelled by type.Open tool Name Server LookupFind a domain's authoritative nameservers and the provider behind them.Open tool CNAME LookupFollow a CNAME chain to its final target and catch loops and dangling aliases.Open tool DNS TTL LookupCheck the TTL on a domain's A and AAAA records and learn what to set.Open tool Reverse DNS LookupFind the PTR hostname for an IPv4 or IPv6 address and check it resolves back.Open tool
Email authentication
Check the SPF, DKIM and DMARC records that decide whether your mail is trusted.
SPF Record CheckerValidate an SPF record, count its DNS lookups against the limit of 10 and see what to fix.Open tool DMARC Record CheckerLook up and validate a DMARC policy, with every tag explained.Open tool DKIM Record LookupFetch a DKIM public key by selector and check its format and strength.Open tool
IP and network tools
Subnet maths, IP details and the other numbers behind a network.