In short. Verify a claimed Googlebot request by checking its source IP against Google's common-crawler ranges or completing reverse and forward DNS lookups.
Definition: Googlebot request verification checks the source IP address of a request claiming to be Google's search crawler. As of 17 October 2026, Google documents reverse and forward DNS checks for individual requests, or comparison with published crawler IP ranges for automated verification.
Key facts
- Google's Googlebot documentation warns that other crawlers often spoof its HTTP
User-Agentrequest header. - Google's request verification guide requires a forward DNS lookup after the reverse lookup, with the result matching the original source IP address.
- Google's common crawler reference identifies
common-crawlers.jsonas the published address list for the crawler category containing Googlebot.
Why check the address before blocking a request?
A user agent is an HTTP request header identifying the requesting software. Google's Googlebot documentation explains that the header distinguishes Googlebot Smartphone from Googlebot Desktop, while also warning about impersonation by other crawlers.
The same documentation recommends verifying problematic requests before blocking Googlebot. Blocking it affects Google Search and its features, alongside products including Google Images, Google Video and Google News. Address verification therefore matters when deciding whether traffic reported as Googlebot actually warrants a crawler-specific restriction.
How does the DNS check work?
DNS, the Domain Name System, supports lookups between names and IP addresses. Google's verification procedure starts with the accessing IP address recorded in server logs. A reverse lookup retrieves a hostname; a forward lookup then resolves that hostname back to an address.
Google gives this command-line example:
host 66.249.66.1
1.66.249.66.in-addr.arpa domain name pointer crawl-66-249-66-1.googlebot.com.
host crawl-66-249-66-1.googlebot.com
crawl-66-249-66-1.googlebot.com has address 66.249.66.1
The hostname's domain must match the relevant Google crawler category, and the forward lookup must return the original accessing address. The guide covers googlebot.com, google.com and googleusercontent.com across Google's crawler and fetcher categories. Its common-crawler examples use googlebot.com, including the subdomain geo.googlebot.com.
Which address list applies to Googlebot?
Google's common crawler reference groups Googlebot with other common crawlers and documents these reverse DNS hostname patterns:
crawl-***-***-***-***.googlebot.com
geo-crawl-***-***-***-***.geo.googlebot.com
For automated checks, Google's verification guide links to common-crawlers.json. The ranges use CIDR notation, which describes blocks of IP addresses. Verification tests whether the request's source address falls within a published range.
The guide separates common crawlers from special-case crawlers such as AdsBot and from user-triggered fetchers. It also provides a general Google IP list for other Google traffic. The common-crawler list is the relevant starting point for a Googlebot claim; its scope includes multiple crawlers.
Related terms
FAQ
Can I trust a request containing the word Googlebot?
The header alone is insufficient. Google's Googlebot documentation warns that other crawlers often spoof it and recommends checking the source address.
Is a reverse DNS lookup enough?
Google's verification guide also requires the forward lookup. You check that the returned address matches the original request address from your logs.
Does the common-crawler list identify only Googlebot?
It covers a broader category. Google's common crawler reference also lists GoogleOther and Google-InspectionTool, so an address match establishes membership in that shared crawler category.
Sources
- Google, "Verify requests from Google crawlers and fetchers", updated 20 March 2026
- Google Search Central, "Googlebot", updated 3 February 2026
- Google, "List of Google's common crawlers", updated 15 October 2026
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