GlossaryReverse DNS verification

What is reverse DNS verification?

Reverse DNS verification confirms a crawler by looking up the hostname for its IP address, checking that the hostname belongs to the operator’s domain, and then resolving that hostname forward to make sure it points back to the same IP.

Also called: rDNS verification.

It is the older way to verify bots, from before operators published IP lists. Google, Microsoft, Apple and Amazon all document a hostname suffix for their crawlers, such as googlebot.com or applebot.apple.com.

The forward-and-back check matters. Anyone can set the reverse record for an IP they control to say googlebot.com; only the operator can make googlebot.com resolve forward to that IP.

Reverse DNS needs a network lookup per address, which a local, offline tool cannot do silently. agenttraffic uses published ip ranges where they exist and reports agents that only offer reverse DNS as unverified for now.

Related terms

  • Bot verification: Bot verification is checking that a request claiming to be a known bot really came from its operator, by comparing the request’s IP address with the addresses the operator publishes, or by reverse DNS when no list exists..
  • Published IP ranges: Published IP ranges are the lists of IP addresses an operator makes public for its crawlers and agents, so site owners can confirm that a request wearing the operator’s name really came from them..

Published 2026-09-21, updated 2026-09-21.

See it in your logs

One command, nothing to install

Point it at CloudFront, nginx or Apache logs. Every AI agent that visited gets its own row, verified against the addresses its operator publishes.

$ npx agenttraffic ./logs --days 7Quick start

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