Hello Chandra
Yes you are correct, that was my mistake. You cannot explicitly state the MAC address of the interface to be used as a client ID. You can either use the long string of characters that identify the client, or use the interface as a keyword to send the MAC address as the client ID.
I tried labbing up the scenario and I find the following. I am running the command:
R1(config-if)#ip address dhcp client-id GigabitEthernet 0/1
My MAC address of this interface is fa16.3e5d.5fe6. However, when I debug DHCP packets and see what client ID is being sent by the host I see: 01fa.163e.5d5f.e6. It seems the DHCP adds two hex digits of 01 at the beginning of the MAC address to use as the client ID. Remember that the client ID can really be anything, including a DNS name if you configure it that way.
So by using the 01fa.163e.5d5f.e6 value in the client-identifier command in the DHCP server, I was able to have the host obtain the IP address I wanted.
I suggest you try enabling the debugging on the DHCP server as shown in the lesson, to see the actual identifier being used, and copy and past that as the identifier in the DHCP pool.
I hope this has been helpful!
Laz