DNS pulling BGP routes?

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Fri Oct 8 04:03:00 UTC 2021

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
> Then we agree:

Do we?

> The failure mode was that after the data centers
> disconnected from each other, all their DNS expired, breaking the
> tools they'd normally use to recover.

It means DNS management of facebook is poor.

If they are using standard expire mechanism, they should have
used two zones facebook.com for external users with short
expire and internal.facebook.com for internal users with long

> Facebook withdrawing the BGP
> routes to its anycasted public DNS servers as they expired made no
> difference.

If they are not using standard expire mechanism expecting
internal data still accessible even after external data
has expired, there is difference.

						Masataka Ohta

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