---
title: "What is ASN (Autonomous System Number)?"
url: "https://lookvalid.com/glossary/asn.md"
canonical_url: "https://lookvalid.com/glossary/asn"
last_updated: "2026-10-17"
type: "conceptual"
summary: "An Autonomous System Number identifies a network that is run under a single routing policy, such as an internet provider."
related: ["https://lookvalid.com/glossary/ip-geolocation.md", "https://lookvalid.com/glossary/datacenter-ip.md", "https://lookvalid.com/glossary/cidr.md", "https://lookvalid.com/glossary/rdap.md", "https://lookvalid.com/products/ip.md"]
---

# What is ASN (Autonomous System Number)?

An Autonomous System Number identifies a network that is run under a single routing policy, such as an internet provider.

An Autonomous System Number identifies a network that is run under a single routing policy, such as an internet provider, a cloud company or a large organization.

Regional internet registries hand out ASNs, and networks announce their address blocks to each other with BGP under that number. Mapping an IP address to its ASN therefore names the organization that routes it.

The ASN is a strong clue to what kind of traffic you are seeing: a home provider, a mobile carrier, a hosting company or a cloud platform.

## Related

- [What is IP geolocation?](https://lookvalid.com/glossary/ip-geolocation.md)
- [What is Datacenter IP?](https://lookvalid.com/glossary/datacenter-ip.md)
- [What is CIDR (Classless Inter-Domain Routing)?](https://lookvalid.com/glossary/cidr.md)
- [What is RDAP?](https://lookvalid.com/glossary/rdap.md)
- [IP Intelligence API](https://lookvalid.com/products/ip.md)