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As we can see from the first graph that some sites are replicated (e.g. DNS root name servers, Yahoo) and we ignore them in our results, others are not at a permanent location (e.g. supecomp moves annually with the locvation of the SupeComputing show) or use strange routing (e.g. the site labelled 134.79 a SLAC host located elsewhere, though the routing goes through SLAC). We ignore such hosts in our results, though we note that this analysis has clearly pointed out such anomalies. It is also seen that some values for Mexico are aberrant for example min rtt >200 for a Mexican site from Florida. So it is a good idea not to include Mexico in this region. This region will therefore comprise of Canada and US only.
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