# DHCPv6 Server

You can enable an interface to send Dynamic Host Configuration Protocol version 6 (DHCPv6) information to DHCPv6 client devices. By default, the security device does not perform DHCPv6 server actions. DHCPv6 servers can send long-lived prefixes to DHCPv6 clients that they can push downstream to individual local hosts.

## Enabling a DHCPv6 Server Instance

To enable a DHCPv6 server, perform the following steps:

1. Click DHCP Server to enable the DHCPv6 feature.

2. Select the DUID setting(s) necessary for your network:
   - Enable
   - Send Rapid Commit: This is an optional setting. If enabled, the client/server interaction requires two instead of four messages.
   Note: For more information about how rapid commit can affect your network, refer to RFCs 3315 and 3633.

3. (Optional) Indicate Server Preference Number. The default value is -1 (no priority). The range is from 0 (lowest priority) to 255 (highest priority). When the server preference is (-1), the DHCPv6 client does not receive the server-preference option in the advertise messages. DHCPv6 clients use this value to select one server over another.

4. Enter the IPv6 addresses for DNS#1 (primary server), DNS#2 (optional secondary server), and DNS#3 (optional tertiary server).

5. (Optional) Enter 1 to 16 DNS Search List entries.

6. To save your preferences, click Apply .

## Disabling a DHCPv6 Server Instance

To disable a DHCPv6 server, click None, then Apply.

## Adding a DNS Search List

You can add up to 16 DNS search list entries. To add a DNS search list, enter an ID number (from 0 to 15) and a name, then click Add in the Action column of the DNS Search List table. Note: The table resizes to accommodate entry names; however, unusually long names (in excess of 40 characters) might require you to scroll while working in the browser and might affect performance.

## Deleting a DNS Search List Entry

You can delete an entry by clicking Remove. Click OK in the dialog to confirm that you want to delete the entry. Once you delete an entry, it cannot be recovered.