About this tool
PTR record for an IPv4 or IPv6 address, and whether it resolves back (FCrDNS). Lookups go straight from your browser to public services: DNS-over-HTTPS resolvers, the regional internet registries’ RDAP service and the crt.sh certificate log search.
Free to use, no sign-up. We don’t log or store what you look up.
Review your firewall rules too
Paste a config from 12 firewall platforms — plus switches, Wi-Fi, NAC, Azure NSG, NetScaler, F5 and more — and get a graded review with fix commands, mapped to 16 standards. The config never leaves your browser.
Start free See a sample report