William Herrin wrote:
Facebook's _internal_ DNS, while not anycasted, followed a similar logic: if the data center is isolated and their data goes stale, they stop serving potentially wrong answers.
As I already wrote, that is a standard mechanism of DNS with SOA expiration period as is documented in rfc1034 as ("an discard" should be "and discard"): If the secondary finds it impossible to perform a serial check for the EXPIRE interval, it must assume that its copy of the zone is obsolete an discard it. But, that has nothing to do with anycast or route (BGP or IGP) withdrawal.
I didn't work for the DNS team when I worked as a production engineer for Facebook but I worked close enough to understand what happened from the posted description.
I don't think those who post the description properly understand what is wrong with their management. Masataka Ohta