To avoid having a single point of failure, a second recursive DNS server
is necessary. This will be useful in cases where the VM hosts must both
be taken offline, but Internet access is still required.
The new server, *dns1.pyrocufflink.blue*, has all the same zones defined
as the original. It forwards the *pyrocufflink.blue* zone and
corresponding reverse zones to the domain controllers, and acts as a
slave for the *pyrocufflink.red* zone.
*smtp1.pyrocufflink.blue* is a VM that will replace
*smtp0.pyrocufflink.blue*, a Raspberry Pi.
I decided that there is little use in having the availability guarantee of
a discreet machine for the SMTP relay. The only system that would NEED
to send mail if the VM host fails is Zabbix, which operates as its own
relay anyway. As such, the main relay can be a VM, and the Raspberry Pi
can be repurposed as a recursive DNS server.
The *ssh-hostkeys* role is used to manage the global SSH host key
database. This file is consulted by the `ssh` command when verifying
remote host keys on first connect. If the host key is found here, it is
copied to the user's host key database file without prompting for
verification.
Dustin