[dns-operations] Too Open (Was: OpenDNS makes your Internet work better

[Nicholas Suan]

On 7/13/06, brett watson <brett at the-watsons.org> wrote:
>
> you seem stuck on the concept that "ultrdns had only TWO
> authoritative name servers listed for .org" when in fact the number
> of authoritative servers listed for a zone in an anycast environment
> has *no* bearing on how many resolvers are actually active and able
> to resolve queries.
>

It's not any of those seperaly, it's both taken together that was the problem:

UltraDNS had two NS records for org.

UltraDNS also had two 'pods' fail simultaneously, in such a way that
they continued to advertise the prefix without being able to respond
to queries.

In some parts of the internet, the area serviced by these two pods
overlapped, causing a complete outage.

Had there been more NS records, and no overlap of address space being
serviced by the pods, the failure of the two pods would not have been
a problem as the number of available nameservers would have been
greater than the number of failed pods.