Why it matters
Google finds a bot-challenge page very hard to recognise as an error. Served with 200 on many URLs, the identical page can make Google cluster those URLs as duplicates and drop them, and recovery is slow because Google has little reason to recrawl duplicates. A 200 error page is also a soft 404.
How to meet it
If a crawler must get a challenge or block page, send it with 503 (temporary), as Google's CDN guidance recommends for bot-verification interstitials, or 429 for rate limiting; never 200. Most CDN and bot-management products let you set the status code of challenge responses. Better still, do not challenge verified Google crawlers at all (DEV-SRV-01). A CDN that throttles crawlers by injecting 429 or 503 responses on the network path shows up as a rise in HTTP errors in crawl reports.
How to test it
Request a few URLs with a Googlebot user agent from an unverified IP: any challenge comes back as 503 or 429, never 200. The Page indexing report shows no sudden rise of "Duplicate" or "Soft 404" on unrelated URLs.
How Regensbot covers it
Decided from one URL.
An audit reads the response, the headers, the HTML, robots.txt, the sitemaps and the structured data, and the finding shows the evidence it saw.
Sources
Google documents02
- 01Crawling December: CDNs and crawlingSearch Central blog (24 December 2024) (opens in a new tab)
- 02How HTTP status codes affect Google's crawlersGoogle (opens in a new tab)
Claims in the knowledge base07
- D2-C376SourceHandling web duplicationGoogle's documentation
- D2-C374ConsistentHandling web duplicationSaid on stage
- D2-C375ConsistentHandling web duplicationSaid on stage
- D1-C078n/aHow crawling errors affect SearchThe author's interpretation
- D2-C378n/aHandling web duplicationThe author's interpretation
- D1-C367ConsistentHow crawling errors affect SearchSaid on stage
- D1-C364ConsistentHow crawling errors affect SearchSaid on stage
Claim IDs refer to the Search Central Live 2026 knowledge base. The knowledge base (opens in a new tab)
- Consistent
- Google's documentation supports it without stating it.
- Source
- The claim is the cited document itself.
- n/a
- Nothing to verify: a quotation, framing, opinion or analysis.