ASN Lookup
Find autonomous system information for any IP or AS number
Examples: 8.8.8.8, AS15169, 1.1.1.1, AS13335
About ASN Lookup
An Autonomous System Number (ASN) is a unique identifier assigned to a network or collection of networks that share a single routing policy. ASNs are fundamental to how the internet routes traffic between different networks.
How BGP Routing Works
BGP (Border Gateway Protocol) is the routing protocol that connects autonomous systems together. Each AS announces its IP prefixes to neighboring networks, building a global routing table that determines how traffic flows across the internet. When you visit a website, your data may traverse multiple autonomous systems before reaching its destination.
Regional Internet Registries (RIRs)
North America, parts of the Caribbean
Europe, Middle East, Central Asia
Asia-Pacific region
Latin America, Caribbean
Africa
IP Address Allocation
IP addresses are distributed in a hierarchical system. IANA allocates large blocks to the five RIRs, which then assign smaller blocks to ISPs and organizations. These organizations announce their allocated prefixes via BGP from their autonomous systems, making them reachable on the internet.
Related tools: Use our IP Lookup tool to find the geolocation of any IP address. Check your own IP address or look up DNS records for any domain.
Frequently Asked Questions
What is an ASN (Autonomous System Number)?
An ASN is a unique number assigned to a network or group of networks under a single administrative policy. ISPs, cloud providers, and large organizations have ASNs. For example, Google's primary ASN is AS15169 and Cloudflare's is AS13335.
How do I find my ISP's ASN?
Enter your IP address in our ASN Lookup tool, and it will show which Autonomous System your IP belongs to, including the ASN, organization name, and the IP ranges they manage.
What can ASN information tell me?
ASN data reveals the network operator responsible for an IP address, their allocated IP ranges, peering relationships with other networks, and geographic distribution of their network. This is useful for network troubleshooting, security research, and understanding internet routing.
What is BGP and how does it relate to ASNs?
BGP (Border Gateway Protocol) is how Autonomous Systems exchange routing information on the internet. Each AS uses BGP to announce which IP prefixes it manages, allowing traffic to be routed correctly across the global internet.
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