This seems to be an ongoing issue that is still reproducable in the latest Ubuntu Vbox 6.x.
The default NAT Network range is usually 10.0.2.0/24. If you change this range it does not seem to work properly.
Say we change the range to 10.50.1.0/24
If you get a new lease you will find that you get an IP from the old range but the default gateway is from the new range.
........
Enable "cli" mode equivalent in JunOS
cli
Configure Mode
configure
So rather than going to the console on a Cisco switch and typing "enable" and then "conf t", the equivalent in JunOS is "cli" and "configure".
How Do You Apply Changes You've Made?
You can make all kinds of changes to the switch, but remember they are not........
I've got one of these for testing projects from work at home and got more than I bargained for with the time I've spent on it due to the storage handing/Perc 6/i cards.
My particular model came with the following:
2U Rack Mount Server with Rails
2xOpteron 2373 EE (Quad Core, there is a 6-core version that can be found at times)
16GB RAM
2 x 250GB Seagate SATA
2 x Dell Perc 6/i (horrible and a nightmare to work........