What is an ASN (autonomous system number)?
Understand the autonomous system and network organization shown in your IP result, and why the name may not match your provider’s brand.
Networks that make up the internet
The internet is a network of independently operated networks called autonomous systems. Each is run by one organization — an internet provider, mobile carrier, cloud platform, university or large company — and has a unique autonomous system number (ASN).
Autonomous systems announce the address blocks they serve to each other with the Border Gateway Protocol (BGP). The ASN in your IPNIXA result is the network that announces your public address.
An announcement says, in effect, “send traffic for 203.0.113.0/24 to me”. The /24 is a prefix length: it covers the 256 addresses from 203.0.113.0 to 203.0.113.255. Your own public address sits inside one of the prefixes your provider announces.
When you open a website, your traffic usually crosses several autonomous systems: your provider’s, one or more transit or exchange networks, and the network that hosts the website. Each one decides where to send the traffic next based on the announcements it has received.
Who assigns ASNs
ASNs and IP address blocks are distributed by five regional internet registries: AFRINIC, APNIC, ARIN, LACNIC and RIPE NCC. Original numbers were 16-bit, up to 65535; 32-bit numbers now extend the range into the billions.
Some ranges are reserved, which is why the local demo of IPNIXA can safely use AS64500.
| Range | Purpose |
|---|---|
| 0 | Reserved, never used for routing |
| 64496 – 64511 | Documentation and examples (16-bit) |
| 64512 – 65534 | Private use inside networks (16-bit) |
| 65536 – 65551 | Documentation and examples (32-bit) |
| 4200000000 – 4294967294 | Private use inside networks (32-bit) |
| Most other numbers | Assigned to real networks by the registries |
Examples you may recognize
Large platforms operate their own autonomous systems. For example, AS13335 is Cloudflare and AS15169 is Google. Your home provider and your mobile carrier each have their own ASN, and large providers often operate several for different countries or services.
If you check your result on Wi-Fi and then on mobile data, you will usually see two different ASNs and organizations — one for each provider.
Why the organization name can surprise you
The organization shown is the registered holder of the network, which may be a parent company, a wholesale carrier or a former brand rather than the name on your bill. Resellers and virtual mobile operators often use another company’s network.
Seeing a cloud or hosting company usually means traffic leaves through a VPN, proxy, corporate gateway or privacy relay hosted in a data center.
- Parent company or older brand: the network was registered before a rename or merger.
- Wholesale network: your provider rents capacity from a larger operator.
- Mobile virtual operator: your SIM provider uses a host carrier’s network.
- Hosting or cloud company: a VPN, proxy, privacy relay or company security service is in the path.
How to look up an ASN
Once you know the number, public records tell you more about the network.
- Open IPNIXA and read the autonomous system in the network section, for example AS64500.
- Search the regional internet registry databases (each registry offers a public search) for the number to see the registered holder and contact details.
- Check PeeringDB, a public database where many networks publish their peering and contact information.
- When reporting a routing problem, give the support team the ASN, your public address and the time of the test.
How the ASN helps in troubleshooting
Support teams use the ASN to identify which network handles your traffic. If a website is unreachable only from one provider, the ASN shows where routing should be investigated.
The ASN identifies a network, not a household or device. Like location data, it is useful context for diagnosing connections, not a way to identify a person.
Frequently asked questions
Is the ASN the same as my internet provider?
Usually it is your provider’s network, but the registered name may be a parent company, wholesale carrier or older brand. A hosting company name means your traffic is leaving through a VPN, proxy or relay.
What is BGP?
The Border Gateway Protocol is how autonomous systems tell each other which address blocks they can deliver traffic to. Every router at the edge of a network uses these announcements to choose where to send traffic next.
Can I get my own ASN?
Organizations that connect to more than one upstream network can apply through their regional internet registry or a registry member. Home users do not need one.
Why does my result show Google, Amazon or Cloudflare?
You are probably using a VPN, proxy, privacy relay or company security service running in that provider’s data centers, so websites see the provider’s network instead of your ISP.
Does the ASN reveal my location?
Only indirectly. It tells you which network carries your traffic; a provider can cover a whole country or several countries.