It wasn't DNS in principle that caused the outage. If I recall correctly, it was their DNS servers that did that in a convoluted kind of way but not because of

It wasn't DNS in principle that caused the outage. If I recall correctly, it was their DNS servers that did that in a convoluted kind of way but not because of DNS as such. Due to some connection error or another the servers that also run DNS ordered the routers to withdraw the BGP routes to all Facebook properties which in turn killed access to said DNS servers.