Free Tool · BGP & registry data

ASN lookup: who runs this network?

Enter an AS number such as AS15169, or an IP address, to see the network’s owner, country and registry, when it was allocated, and every IP block it announces. Your own network is shown to start.

Look up an ASN

Try:

How to use the ASN lookup

  • By number: type AS13335 or just 13335.
  • By IP address: type an IPv4 or IPv6 address to find the network that routes it and the block it belongs to.
  • See the blocks: open “Announced IP blocks” for every prefix the network announced over the last two weeks.

ASN, IP block and IP address

The internet is a network of about 75,000 networks. Each one that routes traffic on its own has an autonomous system number. It announces the IP blocks (prefixes such as 8.8.8.0/24) it can deliver, and every single IP address sits inside one of those blocks.

ExampleASNNetwork
8.8.8.8 (Google DNS)AS15169Google LLC
1.1.1.1 (Cloudflare DNS)AS13335Cloudflare, Inc.
9.9.9.9 (Quad9 DNS)AS19281Quad9
Facebook and InstagramAS32934Meta Platforms, Inc.

Numbers up to 65,535 are the original 16-bit ASNs; newer ones go up to about 4.29 billion. Ranges such as 64,512–65,534 are private and never appear on the public internet.

Why people look up ASNs

  • Troubleshooting: see which provider carries traffic for a site, or whether two addresses belong to the same network.
  • Security: block or allow a whole hosting provider in a firewall, or recognise traffic from data centers rather than homes.
  • Abuse reports: find the network operator responsible for an address and its abuse contact.

For the registration record of a single address, use the IP WHOIS lookup; for its estimated location, IP Location.

Frequently asked questions

What is an ASN?

An autonomous system number identifies a network that decides its own routing on the internet, such as an internet provider, a cloud company or a university. Each one announces the IP address blocks it handles, and routers worldwide use those announcements, through BGP, to deliver traffic.

How do I find the ASN of an IP address?

Type the IP address into the box. The tool finds which network announces the block that contains it, then shows that network’s number, name and country, and the exact block your IP is in.

What is my ASN?

The tool looks up your own IP when the page opens, so the first result is the network your connection goes through, normally your internet or mobile provider.

Where does the data come from?

The IP-to-ASN mapping and names come from Team Cymru’s public IP-to-ASN service, the registration details from the regional internet registries’ RDAP servers, and the list of announced blocks from RIPEstat, run by the RIPE NCC.

Why does one company have several ASNs?

Large companies often run separate networks for different regions, products or acquired businesses, and each gets its own number. Google, Amazon and Microsoft each operate many.

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