DNS pulling BGP routes?

Wed Oct 6 22:37:54 UTC 2021

On 10/6/21 3:33 PM, Jon Lewis wrote:
> On Wed, 6 Oct 2021, Michael Thomas wrote:
>
>>>  People have been anycasting DNS server IPs for years (decades?). 
>>> So, no.
>>>
>> But it wasn't just their DNS subnets that were pulled, I thought. I'm 
>> obviously really confused. Anycast to a DNS server makes sense that 
>> they'd pull out if they couldn't contact the backend. But I thought 
>> that almost all of their routes to the backend were pulled? That is, 
>> the DFZ was emptied of FB routes.
>
> Well, as someone else said, DNS wasn't the problem...it was just one 
> of the more noticeable casualties.  Whatever they did broke the 
> network rather completely, and that took out all of their DNS, which 
> broke lots of other things that depend on DNS.
>
Maybe the problem here is that two things happened and the article 
conflated the two: the DNS infrastructure pulled its routes from the 
anycast address and something else pulled all of the other routes but 
wasn't mentioned in the article.

Mike