DNS pulling BGP routes?
Michael Thomas
mike at mtcc.com
Wed Oct 6 22:22:43 UTC 2021
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 at 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
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