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In our experience, it only works for routers in Australia and Japana handful of routers.
Examples
-TULIP trace is red, Maxmind trace is blue and Undns trace is orange.
Traceroute from brunsvigia.tenet.ac.za (Cape Town, South Africa) to ping.riken.jp (Tokyo, Japan). Here Undns misses Europe and Maxmind misses North America. TULIP shows the actual path.
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Traceroute from pinger.cern.ch (Switzerland) to mel-a-ext1.aarnet.net.au (Melbourne, Australia). Here Undns is only able to identify the last two hops in Sydney and Melbourne respectively. It is unable to identify the routers in North America.
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Traceroute from www-wanmon.slac.stanford.edu (Menlo Park,USA) to nust.edu.pk (Islamabad, Pakistan). Undns fails to locate even a single router.