An Autonomous System Number (ASN) identifies a network or group of IP prefixes operated by a single organization under a common routing policy. Internet service providers, cloud platforms, CDNs, and large enterprises use ASNs in BGP routing.
An ASN lookup helps you identify which organization controls a network, which regional internet registry assigned the number, and whether traffic belongs to a cloud provider, ISP, or enterprise network.
Network engineers use ASN lookups for troubleshooting routing issues, security teams use them for enrichment and traffic classification, and analysts use them to understand which company sits behind a given network.