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SonicOS 5.8.1 Administrator Guide
To configure Option Objects, Option Groups, and Trusted Agents, click the Advanced button.
For detailed information on configuring these features, see “Configuring Advanced DHCP
Server Options” on page 389.
Configuring DHCP Server Persistence
DHCP server persistence is the ability of the firewall save DHCP lease information and to
provide the client with a predictable IP address that does not conflict with another use on the
network, even after a client reboot.
DHCP server persistence works by storing DHCP lease information periodically to flash
memory. This ensures that users have predicable IP addresses and minimizes the risk of IP
addressing conflicts after a reboot.
DHCP server persistence provides a seamless experience when a user reboots a workstation.
The DHCP lease information is saved, and the user retains the same workstation IP address.
When a firewall is restarted, usually due to maintenance or an upgrade, DHCP server
persistence provides the following benefits:
• IP address uniqueness: Lease information is stored in flash memory, so the risk of
assigning the same IP address to multiple users is nullified.
• Ease of use: By saving the lease information in the flash memory, the user’s connections
are automatically restored.
To configure DHCP Server Persistance, select the Enable DHCP
Server Persistence
checkbox. Optionally, you can modify how often the DHCP server stores DHCP lease
information by modifying the DHCP Server Persistence Monitoring Interval field. The default
is 5 minutes.
DHCP Server Lease Scopes
The DHCP Server Lease Scopes table displays the currently configured DHCP IP ranges. The
table shows:
• Type: Dynamic or Static.
• Lease Scope: The IP address range, for example 172.16.31.2 - 172.16.31.254.
• Interface: The Interface the range is assigned to.
• Details: Detailed information about the lease, displayed as a tool tip when you hover the
mouse pointer over the Details icon.
• Enable: Check the box in the Enable column to enable the DHCP range. Uncheck it to
disable the range.
• Configure: Click the configure icon to configure the DHCP range.
Current DHCP Leases
The current DHCP lease information is displayed in the Current DHCP Leases table. Each
binding entry displays the IP Address, the Ethernet Address, and the Type of binding
(Dynamic, Dynamic BOOTP, or Static BOOTP).
To delete a binding, which frees the IP address on the DHCP server, click the Delete icon
next to the entry. For example, use the Delete icon to remove a host when it has been
removed from the network, and you need to reuse its IP address.