ASN Lookup
Enter an AS number or an IP address. See who runs the network, where it is registered, every IP range it announces to the internet and the networks it connects to.
The lookup goes from your browser straight to RIPE NCC’s public routing database. It never passes through our servers, and nothing is stored.
What an ASN Is
The internet is not one network but tens of thousands of them, and each one that routes traffic independently has an autonomous system number. Your broadband provider has one, so do Google, Cloudflare, every mobile carrier and most universities. When two networks exchange traffic, they announce to each other which blocks of IP addresses they can deliver — and those announcements are what this lookup reads. The longer explanation: what is an ASN.
How to Read the Result
| Field | What it means |
|---|---|
| Holder | The organisation the AS number is registered to, as the registry records it. Often a legal company name rather than the brand you know. |
| Registry and country | Which of the five regional internet registries assigned the number, and the country it was registered in. That is where the organisation is, not necessarily where its servers or users are. |
| Announced | Whether the network is currently telling the rest of the internet how to reach it. A registered but silent ASN is common — reserved, retired or simply unused. |
| IP ranges | The prefixes the network announces. The IPv4 address count merges overlapping ranges so nothing is counted twice. |
| Upstream / downstream | Networks seen next to this one in routing paths. Upstream are usually the providers or peers that carry its traffic to the rest of the internet; downstream are usually its customers. A big transit provider has thousands downstream; a home broadband ISP has a handful upstream. |
Announced is not the same as owned. A network can announce addresses it leases from someone else, and owned ranges can sit unannounced for years. For who an address block is formally registered to, use the WHOIS lookup.
What This Can’t Tell You
- Who is behind an address. An ASN identifies a network operator — an ISP, a host, a company — not the person using one of its addresses. Only the operator can match an address to a customer.
- Whether a network is malicious. Every large provider carries some abuse. To see whether a particular address is on a blacklist, use the IP reputation checker.
- Routes almost nobody sees. The range list leaves out routes seen by fewer than ten of RIPE’s collector peers, so a tiny or brand-new announcement can be missing.
- Where the servers physically are. Registration country and server location are different things; a network registered in one country routinely serves several.
Have a list of addresses rather than one network?
Bulk IP Lookup WHOIS Lookup What Is My IPFrequently Asked Questions
What is my ASN?
It belongs to whoever provides your internet connection. The IP checker shows your address and network number; paste that number here to see the rest.
Why does an IP address show more than one ASN?
Occasionally two networks announce the same range — during a migration, for anycast services, or by mistake. When it happens, every origin network is listed and the first is shown in full.
Why does an AS number say “private use” or “documentation”?
Some ranges are set aside and never appear on the public internet: 64512 to 65534 and 4200000000 to 4294967294 are for private networks, and 64496 to 64511 and 65536 to 65551 are reserved for examples in documentation. AS 23456 is a placeholder older routers use for numbers too big for them.
Does the network owner know I looked it up?
No. The lookup reads RIPE’s public routing database; nothing is sent to the network itself.
Where does the data come from?
RIPE NCC’s RIPEstat, built from route collectors that peer with hundreds of networks worldwide. It covers every region, not just Europe, and is refreshed several times a day.