Configuring DHCP Options
Because Cisco IP Phones use TFTP to load phone images, the Security Appliance supports
the dhcpd option command to define the TFTP servers that will be identified to the client by
DHCP. The syntax for this command is as follows:
dhcpd option 66 ascii {server-name | server-ip-str}
dhcpd option 150 ip server-ip1 [server-ip2]
Configuring DHCP Lease Length
The dhcpd lease command specifies the amount of time (in seconds) that the DHCP clients
can use the assigned IP address received from the DHCP server. The syntax for this command
is as follows:
dhcpd lease lease_length
NOTE The difference between these two commands is that the option 150 enables you
to specify a list of TFTP servers to be used by the DHCP client.