[RRG] DNS down vs Network down

[Randall Atkinson <rja@extremenetworks.com>]

Earlier, William Herrin wrote:
% And, it also presupposes that DNS servers/resolvers
% for root, TLDs (especially arpa), and reachable destinations,
% will be available 100% of the time.

This raises a separate point which maybe is worth repeating.

The overwhelming majority of users/deployments today are unable
to distinguish "DNS service unavailable" from "network down".

I first learned this while working in network engineering for a
multi-continent residential broadband ISP in the latter half of
the 1990s.  It has been reinforced repeatedly since then when
I talk with network engineering/operations folks at various
other ISPs around the globe.

Just to be clear, those ISP folks consistently say that this user
inability to distinguish "network down" from "DNS service
unavailable" applies to all sorts of users: residential,
commercial, enterprise, academic/educational, government,
military, and everyone else.

So, for the overwhelming majority of users today, a DNS fault
is viewed as being identical to a hard network fault (such as
a fibre cut or power failure).

I think this means that being more explicitly reliant on DNS
service availability now, versus 20 years ago, is widely acceptable.

Cheers,

Ran


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