Mapping IP -> ASN

Dun Liu dunl at
Fri Nov 15 19:32:26 UTC 1996

You can look at Internet routing table collected by Merit.
(""). But the table
may mislead you to a wrong ASN if the IP address is an inet-rtr. My
suggestion is consulting the table first, and if you think that one IP
might be a inet-rtr, consulting IRR using "whois -h


On Fri, 15 Nov 1996, Lyndon Nerenberg wrote:

> Is there a tool available that will take an IP address and return the 
> ASN attached to that network? I've been in situations before where this 
> information would be useful, but not having access to the BGP routing 
> information I'm not sure how to do this? (I've looked around some 
> "likely" web sites - such as Merit - but haven't found anything.)
> The pressing need is for the ASN associated with This 
> network is connected to I*star, but I can't tell which of I*star's 
> three ASNs it's homed on. (And they aren't being responsive to queries.)
> --lyndon

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