ASN Lookup
Identify and retrieve detailed information about Autonomous System Numbers (ASN), including organization names, countries, and assigned IP ranges.
Looks up live data What you enter is sent to our server to fetch live results from public sources. Results are cached briefly.
About this tool
An Autonomous System Number (ASN) identifies the network that announces an IP address on the internet. Enter an IPv4 address and the tool queries Team Cymru's public IP-to-ASN service through DNS-over-HTTPS, then shows the AS number and name, the announced prefix, the country code, the regional registry and the allocation date. The lookup is made by our server and results are cached for an hour. Only IPv4 addresses are accepted; IPv6 and hostnames are not supported here, so resolve a hostname to an IP first.
How to use it
- Enter an IPv4 address such as 8.8.8.8.
- Press Look up ASN.
- Read the AS number, name, prefix and country.
- Use the prefix to see the full range that network announces.
Common problems
- It asks for a valid IPv4 address
- Enter four numbers from 0 to 255 separated by dots. Hostnames and IPv6 addresses are rejected.
- The AS name is empty
- The name comes from a second lookup that can fail. The AS number and prefix from the first lookup are still valid.
- The country is not where the server physically is
- The country is the registry's record for the prefix, not a physical location.