Network found
An autonomous system announces the address, shown with its prefix, country and registry.
Free ASN lookup for IP addresses and networks
Find the autonomous system, network prefix and country behind an IP address, AS number or domain.
- Free, with no signup
- Runs in your browser
What your result means
No network found
No network announces the address. It may be private or reserved.
Questions about the ASN lookup
What is an ASN?
An autonomous system number names one network on the internet, such as an ISP, a cloud provider or a large company.
Why check the network of a sending IP?
Some blocklists and filters judge whole networks. If your sending IP shares a network with known spam, your email can suffer too.
Can I look up a domain?
Yes. Enter a domain and the lookup uses its first IPv4 address. You can also enter an AS number, such as AS15169.
Found a problem? We will check the rest.
Book a deliverability audit and we will look at every domain and mailbox you send from.