Glossary · Network

ASN (Autonomous System Number)

Also calledautonomous system numberas number

Definition

An ASN identifies a network operator — an ISP, cloud provider, or enterprise — for routing traffic between networks on the public internet.

Explanation

In depth

The public internet is a network of networks — each network is an Autonomous System, and every AS is identified by a globally unique ASN. Comcast is AS7922. Cloudflare is AS13335. Amazon AWS is AS16509. Routing between ASes uses BGP (Border Gateway Protocol) with ASN as the identifier. GeoIP databases and anti-fraud systems fingerprint IPs partly by their ASN — traffic from a residential ISP ASN looks different from traffic from a cloud provider ASN, which is why residential proxies bypass some anti-bot systems that datacenter proxies cannot.

Related terms

IP addressAn IP address is a numeric identifier assigned to each device on a network — how packets know where to go.ISP (Internet Service Provider)An ISP is the company that provides your internet connection — assigns your public IP, routes your traffic, and often enforces country-level blocking policies.IP blockingIP blocking drops packets destined for specific IP addresses at the network firewall level — bypasses DNS entirely.Datacenter proxyA datacenter proxy routes traffic through IP addresses from cloud providers — cheap, fast, but easy for anti-bot systems to detect.

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