About ASNs
An Autonomous System (AS) is a collection of IP address ranges managed by a single organisation and governed by a common routing policy. Each AS is assigned a globally unique ASN by one of the five Regional Internet Registries (ARIN, RIPE, APNIC, LACNIC, AFRINIC). Understanding which AS an IP belongs to helps IT leaders verify cloud egress addresses, identify third-party network dependencies, and investigate suspicious traffic. You can enter an IP address (IPv4 or IPv6) and get the owning ASN, or enter an AS number directly (e.g. AS15169) to look up its registered details.