Best way to make a machine boot with or without a Internet connection

[Steve O'Hara-Smith]

On Thu, 6 Aug 2020 17:20:16 -0400
Aryeh Friedman <aryeh.friedman at gmail.com> wrote:

> Due to storm related damage my ISP went out for a few (12) hours earlier
> in the week and while I got it usable without a Internet connection by
> putting everything in my LAN in /etc/hosts (I also run a local_unbound
> --> local bind9 on my file server which I have created a zone file for
> the LAN machines also), but it was very slow in booting due to ntpdate,
> tomcat and sendmail not being to connect to the Internet for either
> forward or reverse DNS.   I don't want to turn these services off, but I
> want to be able to do a normal boot (no long hangs) if the ISP goes down
> again.   What is the best way to do this?

	Your problem is DNS so I'd suggest solving it at that level. Point
everything at a local DNS service and provide that with the handful of
addresses that you need to boot smoothly (or put them in /etc/hosts where
they're needed) so that it doesn't have to forward queries for them. This
does leave you open to problems if they change of course.

-- 
Steve O'Hara-Smith <steve at sohara.org>