nonexistent-path control

A request for a randomised URL that no site would ever publish, made alongside the real requests. It is the control that tells a scanner whether it reached the site at all: a real site answers it differently from its homepage. Tightened on 1 September 2026 to catch walls that answer with non-HTML, a challenge page of any size, or a block page byte-identical across paths.

Crawlers and access

Who is fetching, whether they are who they claim, and what your rules actually permit.

retrieval crawler · user-triggered fetch · verified crawler · forged crawler identity · unverifiable · robots.txt · user-agent group · AI opt-out · Content-Signal · crawl budget · cloaking · challenge page at 200 · uniform refusal · blocked render resource · off-host redirect · homepage refused · FCrDNS · Crawler trap · Conditional request · ASN blocking · operator feed · residential proxy · Google-Extended · Google-Agent · GPTBot vs OAI-SearchBot · ClaudeBot vs Claude-User · PerplexityBot vs Perplexity-User · CCBot · Bytespider · agentic traffic · crawler classification

← uniform refusal · blocked render resource →

See it in the full glossary · 579 terms across 19 areas. Scan a site to see which of these apply to it.