# DHCP Server Address Allocation

The Dynamic Host Configuration Protocol (DHCP) allocates IP addresses in two modes:

In Dynamic mode, the security device, acting as a DHCP server, assigns (or “leases”) an IP address from an address pool to a host, acting as a DHCP client. The IP address is leased for a determined period of time or until the client relinquishes the address.

In Reserved mode, the security device assigns a designated IP address from an address pool exclusively to a specific client every time that client goes online.

Note: The security device saves every IP address assigned through DHCP in flash memory. Consequently, restarting the security device does not effect address assignments.

### To Create an IP Address Pool for Dynamic IP Address Allocation

1. Select Dynamic.

2. Define the range of IP addresses for the DHCP server to use:

IP Address Start: Enter the starting IP address of the range.
IP Address End: Enter the ending IP address of the range.

3. Click OK to save your changes.

### To Reserve an IP Address for a Host with a Specific Ethernet Address

1. Select Reserved.

2. Assign a specific IP address for a specific client's Ethernet address:

IP Address: Enter the IP address you want to reserve for a given Ethernet (MAC) address.
Ethernet Add ress: Enter the Ethernet (MAC) address of the client for which you want to reserve the IP address.

Note: You can determine the Ethernet (MAC) address of a Windows® NT/2000/XP PC by opening a command window (select Run from the Start menu and then enter cmd in the Open field), then entering ipconfig/all.

3. Click OK to save your changes.