--- title: "Reverse DNS verification: definition | Agent Ready Crawlers" description: "Reverse DNS verification: Checking a client IP by looking up its hostname, confirming the operator's domain. Read 2026-11-04." canonical: https://agentreadycrawlers.com/glossary/reverse-dns-verification site: "Agent Ready Crawlers" last_updated: 2026-11-04 section: "Glossary" --- # Reverse DNS verification: definition | Agent Ready Crawlers > Reverse DNS verification: Checking a client IP by looking up its hostname, confirming the operator's domain. Read 2026-11-04. Source: https://agentreadycrawlers.com/glossary/reverse-dns-verification Site: Agent Ready Crawlers Last reviewed: 2026-11-04 Glossary # Reverse DNS verification In short Checking a client IP by looking up its hostname, confirming the operator's domain, then looking the hostname up again to confirm it maps back to the same IP (forward-confirmed reverse DNS). 9 Index rows verify by reverse DNS, among them Googlebot, Google-CloudVertexBot, GoogleOther. Example: Google: host 66.249.66.1 returns crawl-66-249-66-1.googlebot.com, which resolves back to 66.249.66.1. ## Definition Checking a client IP by looking up its hostname, confirming the operator's domain, then looking the hostname up again to confirm it maps back to the same IP (forward-confirmed reverse DNS). ## Sourced example Google: host 66.249.66.1 returns crawl-66-249-66-1.googlebot.com, which resolves back to 66.249.66.1. [Source](https://developers.google.com/crawling/docs/crawlers-fetchers/verify-google-requests), read 2026-11-04. ## How it shows up here 9 Index rows verify by reverse DNS, among them Googlebot, Google-CloudVertexBot, GoogleOther. - [Verification Ledger](https://agentreadycrawlers.com/verification/) - [Read agent traffic in logs](https://agentreadycrawlers.com/guides/read-agent-traffic-in-logs/) Previous: [Pay per crawl](https://agentreadycrawlers.com/glossary/pay-per-crawl/). Next: [RFC 9309](https://agentreadycrawlers.com/glossary/rfc-9309/). [All 41 terms](https://agentreadycrawlers.com/glossary/). ## Sources - [Verify requests from Google](https://developers.google.com/crawling/docs/crawlers-fetchers/verify-google-requests) read 2026-11-04 Last reviewed 2026-11-04