Hey John - welcome, and thanks for asking! The primary source for IPv6 addresses is from domain name resolution, and we find those domain names from TLS certificates as we ingest them. We also identify IPv6 addresses from HTTP redirects or domain name redirects when scanning. 

Hi Morgan,

Do plans exist to expand IPv6 coverage for other ports and protocols?

Thanks,

John

Hey John, currently we prioritize services found on 443 and 80. It’s not on our roadmap currently to expand IPv6 port coverage but we’re open to entertaining those ideas if there’s enough customer demand!

Thanks for the information; with AWS charging for IPv4 along with others, there has been an increase in IPv6 traffic. I appreciate the clarification on how Censys discovers IPv6 data since scanning the entire address space is unfeasible, minus the UPnP and NTP alternatives to web traffic.