a window similar to that in figure 21 is displayed.
figure 21 dhcp server setup window
dynamic host configuration protocol (dhcp), is a means for computers on a network to obtain their ip settings from a centralized server.
dhcp offers complete centralized management of ip client configurations, including ip addresses, gateway address, dns address and more.
1 enable dhcp server
click this check box to enable or disable the dhcp server. this is disabled by default. leave the dhcp server disabled if there already is a dhcp server on the lan or if manual addressing is used on the lan computers.
2 lease time
this is the amount of time that the ip address is leased, or given to the client machine before the dhcp server attempts to renew that address. if the client still requires the use of the ip address, the dhcp server grants the client the use of that ip address for the same amount of time. if the client no longer requires the ip address, the address is freed and returned to the pool of available addresses to be used again. the default value is 60 minutes.
3 default gateway
enter the ip address of the wan router used by lan clients to access the internet. if nat is being used this will be the lan ip address of the internet firewall.
4 subnet mask
use this value to determine what subnet an ip address belongs to.
5 domain name
type the registered domain name for the network in the domain name box, for example: 3com.com. if you do not have a domain name leave this blank.
6 dns servers
a dns server translates human readable host names into the numeric ip addresses used by computers to route information to the correct machine. you can use multiple dns servers to improve performance and reliability. to specify these manually select the specify manually radio box and type the ip address of the dns server(s) in these boxes.
alternatively, if you are using nat with dhcp client you can select the set dns servers by internet firewalls dhcp client to have these fields set automatically.
7 dynamic ranges
when a client makes a request for an ip address, the internet firewall’s dhcp server leases an address from the dynamic ranges.
prior to offering an address from the dynamic range to a requesting client, the internet firewall first verifies that the address is not already in use by another machine on the lan.
to create a range of dynamic ip addresses to be assigned to requesting clients, type the starting number in the range start box, the ending address in the range end box and then click update.
1 allow bootp clients to use range
click this check box to have dynamic bootp clients configured when they boot. dynamic bootp clients are bootp clients that do not have an ip address assigned to their mac address. they are similar to dhcp clients with the exception that leases are not supported.
2 delete range
to remove a range of addresses from the dynamic pool, select it from the scrolling list of dynamic ranges, and click delete range.
3 static entries
static addresses are used by machines that support bootp or those which require a fixed ip address. for example, machines running web or ftp servers require static addresses.
to create a static ip address to be assigned to a requesting client, type an ip address and the ethernet (mac) address of the client machine in the appropriate boxes and click update.
4 delete static
to remove a static address, select it from the scrolling list of static addresses and click delete static.