What is an ASN?
An Autonomous System Number (ASN) is a unique identifier assigned to each autonomous system on the internet. An AS is a collection of IP networks and routers under the control of one entity that presents a common routing policy to the internet.
ASNs allow organizations to exchange routing information using Border Gateway Protocol (BGP). This is essential for ISPs, data centers, and enterprises needing to control how traffic enters and exits their networks.
Analyzing ASN data helps detect route hijacking, understand internet routing structure, and provide insights into peering relationships between providers. It also helps pinpoint ownership of large IP ranges and track infrastructure globally.
Security teams use ASN lookups to identify potential threat actors, correlate attack traffic, and enforce regional access policies. Understanding ASN distribution is fundamental to maintaining internet stability and performance.
ASN transparency contributes to global routing integrity and helps internet governance bodies maintain accurate records of network allocations and relationships worldwide.