ASN Lookup
Find the ASN and owner of an IP address.
Use the ASN Lookup tool
What this asn lookup does
ASN Lookup queries Team Cymru's public DNS service for the origin autonomous system of an IPv4 or IPv6 address. The result includes the ASN, the registered organisation and the country code, plus the ASN's short name and announced prefix count where available.
This tells you which network announces the address, not who the individual user is. A hosting provider, CDN or VPN can announce addresses on behalf of many customers, and geolocation is approximate. The lookup uses DNS-over-HTTPS and does not send the address anywhere else.
Why use it
- Identify the hosting provider or ISP behind an address.
- Check whether traffic comes from a cloud range or a residential network.
- Find the ASN to report abuse to the right network operator.
How to use it
- 1Enter an IPv4 or IPv6 address.
- 2Run the lookup and wait for the DNS answers.
- 3Read the ASN, organisation and country.
- 4If you need prefixes or contact details, continue on the network's own looking-glass or whois service.
Worked examples
Cloud address
Input
An address in a major cloud range
Output
The cloud provider's ASN and organisation are shown.
IPv6 address
Input
A 2001:db8:: address
Output
The lookup notes that the address is reserved and has no routing origin.
Common mistakes
- Treating the ASN owner as the end user's identity.
- Assuming every address in a prefix belongs to the same customer.
- Ignoring that reserved documentation ranges have no real ASN.
Frequently asked questions
Where does the data come from?
Team Cymru's public IP-to-ASN DNS service, queried over DNS-over-HTTPS.
Can I look up a domain?
Resolve it to an address first, then look up that address. A domain can point to several addresses on different networks.
Is the location exact?
No. Country codes come from registry data and are approximate for anycast and CDN addresses.
Does it show abuse contacts?
Not directly. Use the ASN to find the network's registry entry, which lists abuse contacts.