ASN (Autonomous System Number)
A unique number that identifies a network on the internet — a block of IP addresses run by one organisation. It reveals whether an IP belongs to a home ISP, a data centre, or a mobile carrier.
Full Definition
An Autonomous System Number (ASN) is a globally unique identifier assigned to a collection of IP address ranges under the control of a single organisation — an ISP, a cloud provider, a university, or a mobile carrier. Every IP address on the internet belongs to an AS, and the ASN is publicly visible through BGP routing tables. Anti-bot systems use ASN lookups to classify incoming traffic: IPs from residential ISP ASNs (like Comcast or BT) are trusted; IPs from datacenter ASNs (like Amazon AWS or DigitalOcean) are flagged as likely bot traffic. Knowing an IP's ASN helps you choose the right proxy type for a target site.
