Get detailed information about any Autonomous System Number (ASN) including IP prefixes, related ASNs, organization details, and more.
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Everything you need to know about ASN lookup
An ASN (Autonomous System Number) is a unique number assigned to a network on the internet that has its own routing policy. Large networks like Google, Cloudflare, and Amazon each have their own ASN.
You can use our ASN lookup tool to search for any ASN. To find the ASN for your IP address, use our IP WHOIS tool which will show the ASN associated with your IP.
An IP address identifies a specific device on a network. An ASN identifies an entire network (autonomous system) that owns and manages many IP addresses. One ASN can contain thousands or millions of IP addresses.
IP prefixes are ranges of IP addresses that an ASN announces to the internet. They are expressed in CIDR notation (e.g., 8.8.8.0/24) and represent blocks of IP addresses that belong to that autonomous system.
BGP peering is how different ASNs exchange routing information with each other. Networks establish peer relationships to route traffic between their networks efficiently.
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