Note that the particular case in question could also be an implementation of Cisco's DistributedDirector product, which responds to DNS requests with the closest server to the querying machine. /cah On Mon, Aug 02, 1999 at 02:59:05PM -0600, Alec H. Peterson wrote: ==> ==>Martin Cooper wrote: ==>> ==>> Some weeks ago I noticed that 167.216.128.247/32 ==>> (www.digisle.net) appears to reach web servers ==>> located in physically different places broadly ==>> dependent on where you see it from. ==>> ==>> I presume this is done by advertising the same ==>> prefix from border routers which are in seperate ==>> IGP domains or something (confederations maybe?), ==>> but I wonder what people's views on the concept are, ==>> since it could potentially be quite confusing in ==>> certain circumstances (e.g. debugging routing ==>> problems) ? ==>> ==>> Superficially it seems like a 'cool hack' for ==>> geographic content-distribution (which is what ==>> Digital Island do), but up until now I've always ==>> seen this sort of thing done by exploiting NS ==>> record sorting order properties with the kludge ==>> of different A records in the various zonefiles, ==>> and I wondered if doing it with routing policy in ==>> this way is strictly RFC compliant (or for that ==>> matter if anyone cares if it isn't) ? ==> ==>This certainly isn't a new idea, although it is generally considered poor ==>form to do this with stateful protocols (such as TCP), since the 'closest' ==>instance of the address can change mid-session, and thus cause a reset. ==> ==>Several presentations on using this hack in various situations have been ==>made at NANOG. See http://www.hilander.com/nanog11 for one such ==>presentation. ==> ==>Alec ==> ==>-- ==>Alec H. Peterson - ahp@hilander.com ==>Staff Scientist ==>CenterGate Research Group - http://www.centergate.com ==>"Technology so advanced, even _we_ don't understand it!"