Is WTFast against ToS?

[Castillan]

THIS. Your data routes change constantly and without you even knowing most of the time.

I wouldn't quite say "constantly", although it may happen around once a day 'cos some router went down for whatever reason, or more rarely (and generally causing much greater disruption) some technician screwed the pooch and punched in a bad BGP config while attempting to support some new network, and then all hell breaks loose as different routers start disagreeing on the best path to route traffic (generally referred to a route-flap). Usually it is noticeable as a significant lag-spike of a few seconds or more, as the routers between yourself and the server attempt to renegotiate the best possible route to work around whatever went dark.

As is quite often the case, Wikipedia provides a half-decent introduction of the topic: http://en.wikipedia.org/wiki/Border_Gateway_Protocol