Guide
What Is an ASN?
An ASN, or Autonomous System Number, identifies a network that participates in internet routing.
What an ASN represents
Large ISPs, hosting providers, cloud networks, universities, and companies often operate autonomous systems.
ASN data can help explain whether an IP belongs to a residential ISP, a datacenter, a corporate network, a VPN, or another network type.
What ASN data does not prove
ASN data is network context, not identity. It does not prove who is using the address at a specific moment.
Cloud, proxy, mobile, and VPN networks can carry traffic for many unrelated users and organizations.
Key terms
- ASN
- Autonomous System Number
- BGP
- Border Gateway Protocol routing
- Organization
- The network operator associated with the ASN data
Examples
ASN format
AS12345
ASN values are commonly displayed with an AS prefix.
Lookup result
AS3292 TDC Holding A/S
Example of a network label returned by an IP lookup.
Look up an IP with ASN data
Related guides and tools
FAQ
Does ASN identify a person?
No. ASN data identifies a routing network or organization, not a person or exact device.
Why does an IP lookup show a hosting provider?
The traffic may come from a server, VPN, proxy, or cloud service instead of a residential internet connection.