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<div class="moz-cite-prefix">On 2016-03-18 01:46, Ron wrote:</div>
<blockquote
cite="mid:CAOAL9US3ZcxOL1iDYLa5icucO3GngYjTGoreqEzaS1UchJuTOQ@mail.gmail.com"
type="cite">
<div dir="ltr"><br>
<div class="gmail_extra">
<div class="gmail_quote">On Fri, Mar 18, 2016 at 12:12 AM,
G.W. Haywood <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:bind@jubileegroup.co.uk" target="_blank">bind@jubileegroup.co.uk</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Hi
there,<br>
<br>
On Thu, 17 Mar 2016, Ron wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
... in this case it's a supplier who is unable to keeps
his DNS servers<span class=""><br>
working, and we just want to keep the connectivity.<br>
</span></blockquote>
<br>
I'd just put something in /etc/hosts and send myself an
email every<br>
month or so to remind me I'd done that.</blockquote>
<div><br>
</div>
<div class="gmail_quote"><br>
</div>
This is what we're currently using, but it has the downside
of not picking up ip address changes.<br>
</div>
</div>
</div>
</blockquote>
<br>
If you want to reinvent caching, why not go a step further,
periodically query the records and build a local /etc/hosts<br>
<br>
I've done this in a couple places where I need certain records to
work even if DNS is broken. For example, it's just not worth having
a NFS or Gluster filesystem mount fail because DNS happens to be
down. If DNS is down, I'm probably already mid-panic, I don't need
to worry about whether or remote file systems will come back up if I
need to reboot a thing.<br>
<br>
My current logic is that I do a SOA query and check the serial
number, if it has changed, I query every needed hostname into a temp
file, and if every single query was successful, check the SOA again,
and if it still matches, update the /etc/hosts. If anything goes
wrong (including a mismatch between the SOA), dump the temp file and
try again.<br>
<br>
Slaving the zones would be better, but some machines have a resolver
already, sometimes with unique configuration that I couldn't
bulldoze (and I'm too lazy to manually review the configuration of
every machine) and sometimes the local resolver was Unbound, and
also the master DNS server doesn't have a list of every machine that
needs a NOTIFY, or a way to keep that list up to date. It was just
faster to code up a sloppy /etc/hosts script to update a handful of
critical records. Lame reasons, but it works well enough and hasn't
blown up in my face yet.<br>
<br>
<pre class="moz-signature" cols="72">--
Dave Warren
<a class="moz-txt-link-freetext" href="http://www.hireahit.com/">http://www.hireahit.com/</a>
<a class="moz-txt-link-freetext" href="http://ca.linkedin.com/in/davejwarren">http://ca.linkedin.com/in/davejwarren</a>
</pre>
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