On Thu, 18 Sep 2003, Leo Bicknell wrote: > A truely robust anycast setup has two "addresses" (or networks, or > whatever), but only one per site. From the momentary outage while > BGP reconverges to the very real problem of the service being down > and the route still being announced there are issues with all anycast > addresses going to one site.
Yes, this is the fatal miscalculation in the ultradns setup. However, the other aspect, hiding most servers and only showing two at a time, isn't exactly the best idea ever either. First of all, it limits the number of usable DNS servers available at any specific location unnecessarily, and second, BGP metrics are a very poor substitute for RTT measurements.