Mapping IP -> ASN

Lyndon Nerenberg lyndon at
Fri Nov 15 17:02:10 UTC 1996

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.)


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