Hello,
Customers who had erroneously pointed DNS records at 1.1.1.1 (or similar addresses) will receive an error 1034 (HTTP 403) going forward when attempting to send traffic via Cloudflare’s proxy.
We now validate that the hostnames landing on an IP address (or set of addresses) are associated with the same account in our systems, preventing misconfiguration and/or potential abuse.
Customers should ensure DNS records are pointed to addresses they control, and in the case a placeholder address is needed for “originless” setups, use the IPv6 reserved address 100:: or the IPv4 reserved address 192.0.2.0