ASN (Autonomous System Number)

An ASN identifies which network operator owns a block of IP addresses, and it's the single signal anti-bot systems check to instantly classify traffic as "residential ISP" (trusted) versus "known datacenter/hosting provider" (flagged)—before ever looking at request headers or behavior. When answering what is an asn, an Autonomous System represents a collection of IP routing prefixes managed by a single administrative entity (such as Comcast, AT&T, or AWS) participating in Border Gateway Protocol (BGP) routing across the internet.

During asn proxy detection, security gateways execute an instant asn lookup against regional internet registries (such as ARIN or RIPE) when a TCP connection initiates. If the ASN resolves to a commercial hosting provider (such as Amazon AS16509, DigitalOcean AS14061, or Hetzner AS24940), WAFs apply aggressive challenge rules. Conversely, ASNs registered to consumer broadband providers (such as Comcast AS7922) are recognized as genuine end-user traffic. For developers understanding residential proxies, ASN classification explains why residential pools maintain superior extraction success compared to datacenter proxies vs. residential proxies on bot-protected domains.

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