ASN
An ASN (Autonomous System Number) is a unique identifier assigned to a network -- an ISP, cloud provider, university, or large company -- that controls its own block of IP addresses and routing policy on the internet. ASNs are what BGP, the protocol that routes traffic between networks, uses to tell one operator's address space apart from another's. Looking up the ASN behind an IP address tells you who actually operates it: a residential ISP, a hosting provider, a mobile carrier, or a cloud platform, which is often more useful than the registered owner name alone when judging whether traffic from an address looks like a home connection, a server, or something else entirely.
By AdminKit team, Netbase JSC · Updated