I was struggling with having Unix machines obtain reserved IP addresses from our Cisco DHCP server, until I found this link. At the end of the page, mkonarski3 mentions the following:
use “hardware-address” (don’t put the 01 in front just the mac addr xxxx.xxxx.xxxx) for your unix box and “client-identifier” for your windows box…
The Ubuntu desktop picked up the reserved/desired address first shot!
via IOS DHCP Server reservation (Windows and linux) | LAN, Switching and Routing | Cisco Support Community | 6016 | 10015846.