Comment 2 for bug 1776604

FWIW, a couple things worth noting:

1. I did tests both ways, in which ens3 had the largest DB id, as well as the smalls DB id, and in both situations, it would always get the default DNS entry.
2. All interfaces were set to Auto Assign to ensure they get an IP from MAAS and a DNS entry.

On the other hand, I did a couple experiments to highlight what was does, so I did this:

a. ens0 (non-PXE interface) was set to 'Auto-Assign'
b. ens3 (PXE interface) was set to 'DHCP'

The results yield as expected, which were:

1. Even though ens3 is the PXE interface, it was set to DHCP, which meant we don't really know the IP this interface has.
2. On deployment, ens0 would get the default DNS entry, because we know the IP, as it was assigned to MAAS.
3. Once the machine PXE boots of MAAS over ens3, it did so because it got an IP from MAAS' DHCP, as such, the default DNS entry was updated to point at ens3's IP address, and ens0 was rolled back to ens0.<hostname>.<domain>, which is expected behavior.