Question 1

What is an ASN?

Accepted Answer

An Autonomous System Number identifies a network that routes traffic under a single policy — a carrier, cloud provider or large enterprise.

Question 2

How do ASNs relate to IPs?

Accepted Answer

IP addresses sit inside prefixes announced by an ASN. Looking up an IP tells you which AS routes it; looking up an ASN tells you who operates the network.

Question 3

Where does the data come from?

Accepted Answer

Registration data is mirrored from the public Team Cymru origin DNS service, whose source data comes from the five regional internet registries (ARIN, RIPE, APNIC, LACNIC, AFRINIC).