Frequently Asked Questions
What is an ASN?
An Autonomous System Number (ASN) identifies a network that has its own independent routing policy on the internet, the entity other networks route traffic to and from via BGP. See our guide on ASN vs ISP for more.
What are "announced routes"?
These are the IP prefixes (ranges) that this ASN has registered as being reachable through it. A single ASN can announce anywhere from one to thousands of routes, depending on how large the network is.
Does this cover ASNs outside Europe?
Yes. This tool covers ASNs registered under all five regional internet registries: AFRINIC, APNIC, ARIN, LACNIC, and RIPE NCC, not just Europe.
Why is there a "Load more routes" button?
Large networks can announce hundreds or thousands of routes. Results load in batches of up to 500 at a time rather than all at once, so the page stays fast even for the biggest ASNs.
Looking up a specific IP address instead?
Try the IP WHOIS Lookup Tool Browse the ASN Directory