Fortinet FortiGate 4000 - Manual (Page 164)

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Fortinet Inc.
Configuring DHCP services Network configuration
You can add multiple scopes to an interface so that the DHCP server added to that
interface can supply IP addresses to computers on multiple subnets.
Add multiple scopes if the DHCP server receives DHCP requests from subnets that
are not connected directly to the FortiGate unit. In this case, the DHCP requests are
sent to the FortiGate unit through DHCP relay. DHCP relay packets contain DHCP
relay IP, which is the IP address of the subnet from which the DHCP relay received the
request.
If the DHCP request received by the DHCP server is not forwarded by a DHCP relay,
the DHCP server decides which scope to use based on the IP address of the interface
that received the DHCP request; usually the scope with the same subnet as the
interface.
If the DHCP request received by the server is forwarded by a DHCP relay, the relay IP
is used to select the scope.
To add a scope to a DHCP server
1 Go to System > Network > DHCP.
2 Select Address Scope.
3 Select an interface.
You must configure the interface as a DHCP server before it can be selected.
4 Select New to add an address scope.
5 Configure the address scope.
6 Select Advanced if you want to configure Advanced Options.
7 Select OK.
Scope Name Enter the address scope name.
IP Pool Enter the starting IP and ending IP for the range of IP addresses that this
DHCP server assigns to DHCP clients.
Netmask Enter the netmask that the DHCP server assigns to the DHCP clients.
Lease Duration Enter the interval, in days, hours and minutes, after which a DHCP client
must ask the DHCP server for a new address.
If you select Unlimited, DHCP leases never expire.
Domain Optionally enter in the domain that the DHCP server assigns to the DHCP
clients.
Default Route Enter the default route to be assigned to DHCP clients. The default route
must be on the same subnet as the IP pool.
DNS IP Enter the addresses of up to 3 DNS servers that the DHCP server assigns
to the DHCP clients.
WINS Server IP Add the IP addresses of one or two WINS servers to be assigned to DHCP
clients.
Exclusion Range Optionally enter up to 4 exclusion ranges of IP addresses within the IP pool
that cannot be assigned to DHCP clients.