[lug] Troubleshooting Transient DNS failures

[Bear Giles]

Could you insert your own caching DNS server?

You could sell it by pointing out that DNS queries are a common way to
exfiltrate data via the payload. (In fact many of us are suspicious that
that's why there was such heavy DNS traffic between the Trump campaign and
Alfa Bank.) Putting in a caching DNS server can go a long way towards
blocking that if your firewall blocks all traffic on port 53 except traffic
to/from your caching DNS server.

Of course it's also a way to send all attempts to hit the facebook servers
into the great bit bucket in the sky. :-)

On Wed, Jan 16, 2019 at 9:41 AM George Sexton <georges at mhsoftware.com>
wrote:

> On 2019-01-16 09:37, Rob Nagler wrote:
> > Not exactly the answer you are looking for, but...
> >
> > Over the years I've found my colo/ISPs had issues with DNS so I
> > switched to Google and now CloudFlare. I find them to be extremely
> > reliable, and moved to CloudFlare, since they aren't Google. Google
> >
> > Your failure is not likely to be local so spending time debugging it
> > may be a total waste of time. Pop and swap. :)
>
> Unfortunately, this is in a corporate setting and that would go over
> like the proverbial lead zeppelin.
>
>
> > One time we were having issues with TCP DNS. One of their caching
> > servers was misconfigured. Another time, certain sites (e.g.
> > github.com [1]) were just failing randomly, which would mess up builds
>
> Yes. I've got Jenkins jobs that are randomly failing and it makes the
> devs unhappy.
>
> I understand I have no control, but a) they ask me why their job failed
> and b) I'm concerned about the perception that the CI/CD pipeline is
> unreliable, and it's my job to make it reliable...
>
> > randomly. As you say, you don't have control of the DNS servers, so
> > you're going to be debugging your ISP/colo (read: maybe the same one
> > :).
> >
> > Rob
> >
> >
> >
> > Links:
> > ------
> > [1] http://github.com
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> --
> George Sexton
> MH Software, Inc. - Home of connectDaily Web Calendar
> https://www.mhsoftware.com/
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