ASN: the neighbourhood numbers of the internet
2 min read
What the AS number (ASN) in a lookup result is, who assigns it, and what an IP's ASN reveals — its role in network diagnosis and VPN detection.
Definition
The internet is not one network but a federation of tens of thousands of interconnected autonomous systems. Each has a number: the ASN. Türk Telekom is AS9121, Google is AS15169. The ASN line in our tool tells you which network your IP belongs to — your neighbourhood on the internet.
What an ASN reveals
A lot: whether the IP belongs to a residential ISP, a datacenter or a university (the backbone of VPN detection — details here), which operator carries your traffic to the world, and who is responsible for a network when investigating unwanted traffic. When geolocation looks wrong, the ASN is illuminating too: an "Istanbul" estimate on an Ankara ISP's ASN shows the record drifted, not reality.
Who assigns them, where to look
Regional registries assign the numbers (RIPE NCC for Europe/Türkiye). Who owns an ASN and which IP blocks it announces is fully public: search the AS number on bgp.he.net or RIPEstat. For the network-curious, the real map of the internet is not IPs but the links between ASNs.
Our tool demonstrates every concept in this guide on your own connection: five-source location, VPN status, ASN and ISP — free, no signup.
Show my IPFrequently asked questions
Can one provider have multiple ASNs?
Yes; large operators may keep acquired companies' networks on separate ASNs or use distinct numbers for international exits. An ASN numbers a network, not a company.
Is my ASN a privacy concern?
No; it is public information derived from your IP anyway, and it identifies your provider — not you as a person.