North American Network Operators Group

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Re: IP Prefixes are allocated ..

  • From: william(at)
  • Date: Mon Nov 28 02:14:43 2005

On Mon, 28 Nov 2005, Glen Kent wrote:

to different Autonomous systems.

Is there a central/distributed database somewhere that can tell me
that this particular IP prefix (say x.y.z.w) has been given to foo AS
IP prefixes are not "given" to AS numbers. They are assigned & allocated to organizations that can choose to announce it themselves (in which
case you may search for ASN name with same organization name as who the ip block is is assigned to) or have their ISP announce it (in this
case ISPs often register ip block in RR - may appear in

I tried searching through all the WHOIS records for a domain name. I
get the IP address but i dont get the AS number.
Any clues on how i can get the AS number?
I suspect what you're really asking is who is announcing a particular
ip address in BGP. If you want to do it by whois, I recommend this:

 whois -h <ip-address>

William Leibzon
Elan Networks
[email protected]