Lookups go from your browser to Google Public DNS (Cloudflare as a fallback) and to rdap.org, which forwards to the registry for that TLD. Some country-code TLDs don't publish RDAP, so registration checks for those will say "unavailable".
Import / export
Copy the JSON to share profiles with your team; paste theirs and click Import to add or replace them (matched by name). Profiles are saved in this browser only.