Re: DNS pulling BGP routes?

[Michael Thomas <mike () mtcc com>]

On 10/6/21 2:58 PM, Jon Lewis wrote:
> On Wed, 6 Oct 2021, Michael Thomas wrote:
>
> > On 10/6/21 2:33 PM, William Herrin wrote:
> > >  On Wed, Oct 6, 2021 at 10:43 AM Michael Thomas <mike () mtcc com> wrote:
> > > >  So if I understand their post correctly, their DNS servers have the
> > > >  ability to withdraw routes if they determine are sub-optimal (fsvo).
> > >  The servers' IP addresses are anycasted. When one data center
> > >  determines itself to be malfunctioning, it withdraws the routes so
> > >  that users will reach a different data center that is, in theory,
> > >  still functioning.
> > Ah, I was wondering if the anycast part was the relevant bit. But 
> > doesn't it seem odd that it would be intertwined with the DNS 
> > infrastructure?
>
> 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.

Mike