Because they rely on broadcast transmissions, DHCPv4 clients can access DHCP servers only on the local network, under normal circumstances. However, it is possible to create a DHCP infrastructure in which one server provides addresses for multiple subnets. To do this, you must install a DHCP relay agent on every subnet that does not have a DHCP server on it.
Many routers are capable of functioning as DHCP relay agents, but in situations where they are not, you can configure a Windows Server 2012 R2 computer to function as a relay agent by using the following procedure.
- In Server Manager, using the Add Roles And Features Wizard, install the Remote Access role, including the Routing role service.
- Click Open The Getting Started Wizard. The Configure Remote Access Getting Started Wizard opens.
- Click Deploy VPN Only. The Routing And Remote Access console appears.
- Right-click the server node and, on the shortcut menu, select Configure And Enable Routing And Remote Access. The Routing And Remote Access Server Setup Wizard appears.
- Click Next to bypass the Welcome page. The Configuration page opens, as shown in Figure 1.
- Select Custom Configuration and click Next. The Custom Configuration page opens.
- Select the LAN Routing check box and click Next. The Completing The Routing And Remote Access Server Setup Wizard page opens.
- Click Finish. A Routing and Remote Access message box appears, prompting you to start the service.
- Click Start Service.
- Expand the IPv4 node. Then, right-click the General node and, in the shortcut menu, select New Routing Protocol. The New Routing Protocol dialog box appears.
- Select DHCP Relay Agent and click OK. A DHCP Relay Agent node appears, subordinate to the IPv4 node.
NOTE: DHCPV6 RELAY AGENTS
You can also create a relay agent for DHCPv6 by adding a routing protocol to the IPv6 node.
- Right-click the DHCP Relay Agent node and, on the shortcut menu, select New Interface. The New Interface For DHCP Relay Agent dialog box appears.
- Select the interface to the subnet on which you want to install the relay agent and click OK. The DHCP Relay Properties sheet for the interface appears.
- Leave the Relay DHCP Packets check box selected, and configure the following settings, if needed.
– Hop-Count Threshold Specifies the maximum number of relay agents through which DHCP messages can pass before being discarded. The default value is 4 and the maximum value is 16. This setting prevents DHCP messages from being relayed endlessly around the network.
– Boot Threshold Specifies the time interval (in seconds) that the relay agent should wait before forwarding each DHCP message it receives. The default value is 4 seconds. This setting enables you to control which DHCP server processes the clients for a particular subnet.
- Click OK.
- Right-click the DHCP Relay Agent node and, on the shortcut menu, select Properties.The DHCP Relay Agent Properties sheet appears, as shown in Figure 2.
- Type the IP address of the DHCP server to which you want the agent to relay messages and click Add. Repeat this step to add additional servers, if necessary.
- Click OK.
- Close the Routing And Remote Access console.
At this point, the server is configured to relay DHCP messages to the server addresses you specified.
This article is a part of 70-410 Installing and Configuring Windows Server 2012 Prep course, more articles in this course are :
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