Q: When should we use "hardware-address <mac-address>" , instead of "client-identifier <>" ?
A: By default Cisco router if configured as DHCP server will serve both BOOTP and DHCP requests. Client-identifier is used for DHCP request and hardware-address is used for BOOTP request. You can also disable to reply for BOOTP request via "ip dhcp bootp ignore" in this case "hardware-address" has no use.
A: By default Cisco router if configured as DHCP server will serve both BOOTP and DHCP requests. Client-identifier is used for DHCP request and hardware-address is used for BOOTP request. You can also disable to reply for BOOTP request via "ip dhcp bootp ignore" in this case "hardware-address" has no use.
Cisco routers by default is configured to send DHCP request so they have client identifier field, but if some devices send BOOTP request then DHCP should be configured with hardware-address. Windows send DHCP request by default, Linux machine sends BOOTP request by default (we can change this behavior as well). So its depends on which device is sending which request and accordingly DHCP serves them.
