If you want to be able to turn off the power of your SONOS components without any hiccups when turning them back on later (e.g. prevent multiple use of the same IP in your local network), it seems advisable to reserve their IP addresses on your router. This is important especially in the case of the Bridge.
For my ZyXEL router this setting can be found under Network -> LAN -> Client List and would look like the following:
DHCP Client Table
|#||Status||Host Name||IP Address||MAC Address||Reserve||Modify|
An easy way to get the MAC addresses of all the SONOS devices is to open Windows Explorer -> Network -> Media Devices and then rightclick or doubleclick on each device icon and choose properties. The MAC address is listed under Troubleshooting Information.