ASN Lookup
Look up the autonomous system (ASN) that announces a domain or IP address's network.
The network that currently announces this address on the public internet, not the domain's registrar.
Enter a domain or IP
The autonomous system, network owner, and country announcing that address.
An Autonomous System Number (ASN) identifies a single network operator on the public internet — an ISP, a cloud provider, a CDN, or a large organization's own network — that controls routing for a block of IP addresses via BGP, the protocol that determines how traffic actually finds its way between networks. Every public IP address belongs to exactly one ASN at any given time.
Looking up a domain's ASN reveals who actually operates the network its IP address lives on, which is frequently not the company running the site — a huge share of the web sits behind a handful of major clouds and CDNs, so the ASN often names the infrastructure provider rather than the business itself. It's most useful for distinguishing self-hosted infrastructure from CDN/cloud-fronted traffic, and for grouping IPs by network when investigating abuse or outages.