ASN lookup

Find the ASN, provider and networks of an IP or AS number

An autonomous system is a network run by one operator: a provider, a host or a large company. Enter an IP to see which AS owns it, or an AS number to see its networks.

Network clusters on a globe: each autonomous system with its own servers and prefixes

What an ASN tells you

Every network on the internet belongs to an autonomous system with its own number. A home provider, a host and a mobile operator each run one or more AS and announce their IP networks to the rest of the internet through BGP.

The AS owner shows whose address you see: a home provider, a data centre or a cloud. Sites and anti-fraud systems use the same data to judge whether a visitor comes through a proxy or a server.

When you need it

Find the provider behind an address from your logs or a proxy list
See all networks of a hosting company before you block or allow it
Check the provider and country of a proxy address before you use it for a task

Questions and answers

01How is an ASN different from WHOIS?

IP WHOIS shows who registered the block and its contacts. The ASN shows who routes the network through BGP right now. Often it is the same company, but a leased block can be registered to one company and announced by another.

02Why does an IP belong to several AS or to none?

Several AS announce the same network for redundancy or anycast. No AS means the block is not announced right now and cannot be reached from the internet.

03Where does the data come from?

From RIPEstat, run by RIPE NCC. It collects BGP routes from collectors worldwide. Your browser sends the query straight to RIPEstat.

04How can an ASN tell me an address belongs to a host?

Look at the AS owner. Hosts and clouds register networks in their own name, so Hetzner, OVH or Amazon shows up at once. Home ISP networks carry the name of the telecom operator.

05What do /24 and /22 mean in the network list?

That is the mask length: /24 is 256 addresses, /22 is 1,024. Networks smaller than a /24 are rarely announced on the internet, so a /24 is the smallest block in the routing table.