ASN (Autonomous System Number)
An ASN is a unique number assigned to a network (like an ISP or hosting company) that controls a block of IP addresses on the internet. It identifies who owns and routes a given range of IPs.
Definition
An Autonomous System Number (ASN) is a globally unique identifier given to an autonomous system, a collection of IP address ranges managed under a single administrative entity such as an ISP, cloud provider, or large enterprise. ASNs are issued by regional internet registries like ARIN and RIPE.
How it works
The internet is a network of networks. To exchange routing information, autonomous systems use the Border Gateway Protocol (BGP), where each network is identified by its ASN (for example AS15169 for Google). BGP announcements tell the world which ASN owns which IP prefixes, so traffic can be routed to the correct network.
Why it matters for proxies and anti-bot systems
ASNs reveal the type of network an IP belongs to. Anti-bot and fraud systems map IPs to ASNs to tell residential ISPs apart from datacenters and hosting providers. Traffic from a known datacenter ASN is far more likely to be flagged or blocked, which is exactly why residential and ISP proxies are valued: their IPs resolve to consumer ISP ASNs that look like real users.
- Classify IPs as residential, datacenter, or mobile
- Detect and block hosting-provider traffic
- Analyze the reputation of an IP range
Examples
AS15169 (Google), AS13335 (Cloudflare), AS7922 (Comcast)
Looking up an IP at bgp.he.net to find its ASN
Anti-bot rule blocking all AWS datacenter ASNs
Common Use Cases
Frequently Asked Questions
Keep Learning
All termsResidential Proxy
A residential proxy routes your traffic through a real device with an IP assigned by an Internet Service Provider, so requests appear to come from a genuine home user rather than a server.
Read definitionDatacenter Proxy
A datacenter proxy is an IP address hosted on servers in a data center rather than assigned by an ISP — offering high speed and low cost, but easier for websites to detect.
Read definitionISP Proxy
An ISP proxy (static residential) is a datacenter-hosted IP that is registered to an Internet Service Provider, combining datacenter speed with residential-level trust.
Read definitionCGNAT (Carrier-Grade NAT)
CGNAT is a technique carriers use to share one public IP among many customers — which is exactly why mobile proxy IPs are so trusted and hard to block.
Read definition