Pro move: type dmarc:yourdomain.com or blacklist:1.2.3.4 straight into the box — it switches tools for you.
About this tool. Classic ICMP ping can't be sent from a serverless edge, so we measure the next best thing honestly: full HTTPS round-trip time to the host, three times in a row. It answers the same question — is the host up, and how far away does it feel.