ASNAutonomous system numbers, 16-bit and 32-bit
ASN lookup
Who operates an autonomous system, where it is registered and how to reach its abuse desk.
What comes back
- AS name and handle
- Holder organisation and country
- Abuse, NOC and routing contacts
- Registration and last-change dates
- Status, including reserved blocks
- Raw RDAP JSON and a text summary
How it works
An autonomous system is a network with its own routing policy, identified by a number in BGP. IANA hands blocks of numbers to the five regional internet registries; DNS Raven picks the right one from IANA's bootstrap file and asks it over RDAP. Private-use and documentation numbers, such as 64512 to 65534, are explained without a lookup.
If a number has not been assigned to an operator, the registry may return the whole block it belongs to; DNS Raven tells you when that happens.
Questions
What is the difference between 16-bit and 32-bit AS numbers?
The original numbers ran to 65535. Since RFC 6793 they go up to 4294967295. Both are looked up the same way; AS23456 is the placeholder older routers see for a 32-bit number.
Which contact should I use to report abuse?
Use the abuse contact when it is listed. NOC and routing contacts are for operational problems such as route leaks, not for spam reports.
Does this show the prefixes an AS announces?
No. RDAP holds registration data only. Which prefixes an AS announces is routing data, seen in BGP looking glasses and route collectors.