Add Option 150 in Cisco Network Registrar.
Select the DHCP cluster.
Select the Advanced tab and click on Custom Options.
Click Add.
Enter Option number 150 and the Option Data Type of IP address. Click OK.
Click on the Policies tab and select your policy.
Add the custom Option 150.
Enter the TFTP IP address under IP address array.
Click on Always send to DHCP clients.
Enter Yes to commit the changes to the database.