Internet2 Network Security SIG

[Steven Wallace <>]

In some of my uses cases, it ensure the resolver continues to have access to the authoritative name server.

For example, caching the TLD entry that points to canvas’s name server (which happens to be hosted in AWS), ensures my resolver is able to refresh its cache for canvas’s domain.

steve

On Nov 2, 2017, at 9:44 PM, Bill Owens <> wrote:

It sounds as though this would solve many problems in your isolated campus scenario, but I wonder about the side effects on providers who load balance by returning different DNS results. It’s not uncommon to see 60-second TTLs in records from cloud providers, sometimes even shorter. I think it is unlikely that the server behind whatever A record BIND decided to stick with would simply go away, but it is possible that server would be overwhelmed by the continuous load from your campus. It might be worth a discussion with your critical cloud providers, if they’re willing to discuss that ‘secret sauce’.

Bill.

On Nov 2, 2017, at 11:00 AM, Steven Wallace <> wrote:

It’s going to get better. BIND 9.12 (currently in beta, GA due out end of year?) supports “serve stale” (see: https://tools.ietf.org/html/draft-tale-dnsop-serve-stale-02). Serving Stale Data to Improve DNS Resiliency - does what you’d expect. If the resolver can’t update a cached entry, it responsed with the its current cached entry. BTW, this would have mitigated the October Dyn outage, which left many in the community without access to Box, PayPal, etc., despite the fact that we had working network paths to these service providers.

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