ASN
An Autonomous System Number is a unique identifier assigned to a network operator, letting anti-bot systems tell residential ISPs apart from data centers.
ASN explained
An Autonomous System Number, or ASN, identifies a group of IP ranges under one administrative operator, such as an ISP, a hosting company, or a large enterprise. Routing on the internet uses ASNs to move traffic between these networks.
For proxies, the ASN behind an IP is a key trust signal. Anti-bot systems check whether an IP belongs to a residential ISP ASN or a well-known hosting ASN, which is exactly why datacenter proxies get blocked and residential and ISP proxies pass. Some providers even let you target IPs by ASN.
Examples
- 01An anti-bot system blocking IPs from known hosting ASNs
- 02Targeting proxy IPs that belong to a specific ISP ASN
- 03Classifying an IP as residential based on its ASN owner
Common use cases
Frequently asked questions
An Autonomous System Number uniquely identifies a network operator and its IP ranges. The internet uses ASNs to route traffic between independently managed networks.
Anti-bot systems read the ASN behind an IP to judge trust. Hosting ASNs signal datacenter proxies and get blocked, while ISP ASNs look residential and pass.
Some advanced providers let you filter IPs by ASN, which is useful when a target trusts specific ISP networks or you need to match a particular provider.
An IP address identifies a single endpoint, while an ASN identifies the whole network operator that owns many IP ranges. One ASN covers many IPs.
They use public routing and registry data that links IP ranges to their owning ASN, then apply reputation rules based on whether that ASN is residential or hosting.