topology: Burch/Cheswick maps


UDP-traceroute from single host 
1 IP addr per prefix in core route table
convert good IPs to hostname  (new & very old, 5k a day)
10k networks per day, full scan 1/month
desists to targets that complain
daily and historical data snapshots available online

 http://www.cs.bell-labs.com/who/ches/map/