An ASN (Autonomous System Number) lookup queries public routing databases to find which organization is responsible for a given IP address or IP range. Every block of IP addresses on the internet is owned by an entity with an ASN, and this data is publicly registered.
What an ASN Lookup Returns
| Field | Example |
|---|---|
| ASN | AS15169 |
| Organization | Google LLC |
| Country | US |
| IP range (prefix) | 8.8.8.0/24 |
| Registry | ARIN (North America) |
How to Look Up an ASN
Use our ASN Lookup tool. Enter any IP address or domain and get the ASN, organization, and IP prefix. You can also look up by ASN number directly to see all prefixes registered to that network.
Why ASN Lookups Are Useful
- Security: Identify if an IP belongs to a known cloud provider, residential ISP, or datacenter (helps detect VPNs and proxies)
- Abuse investigation: Find the organization to report abuse to based on an attacker's IP
- geolocation: ASN registration data often provides more accurate country/region information than IP geolocation databases
- Network engineering: Verify BGP routing, find peering relationships
People Also Ask
- What exactly is an ASN?
- A globally unique 16-bit or 32-bit number assigned to a network (ISP, company, university) that independently controls its own routing on the internet.
- What is an example of an ASN?
- AS15169 is Google's primary ASN. AS701 belongs to Verizon. AS7922 belongs to Comcast. AS16509 is Amazon Web Services.
Related: ASN Lookup | What is an ASN? | WHOIS