Getting ready for the new Ubuntu LTS release 
It looks good, and it feels fast. Rebooting a VM takes 9 seconds, which is faster than ever. No need to schedule maintenance windows any more (not that I did anyway 
).
Network interface configuration and DNS resolution
Things have changed. Both interface configuration and name resolution configuration are now done in /etc/network/interfaces. There is a new flag for autoconfiguration, so no need to echo things to /proc anymore. For our dual stack staticly configured servers the configuration looks like this:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address 192.87.30.54
netmask 255.255.255.192
gateway 192.87.30.1
# This is a statically configured IPv6 interface
iface eth0 inet6 static
autoconf 0
privext 0
address 2001:610:148:dead::54
gateway 2001:610:148:dead::1
netmask 64
dns-search terena.org
dns-domain terena.org
dns-nameservers 2001:610:1:800a:192:87:106:106 2001:610:188:140:145:100:188:188
Note that despite the comment on the second line (see interfaces(5)), not everything is explained there. You have to look at resolvconf(8) as well.