Easy to be a network management - use the three tricks of the DHCP server

The scale of modern enterprise networks is getting bigger and bigger. Facing so many clients, it is very troublesome to manually configure TCP/IP for each machine on the client side. Therefore, many network administrators use DHCP on Windows systems. (Dynamic Host Configuration Protocol) server to dynamically allocate TCP/IP configuration. It’s not unfamiliar to the DHCP server, but are you really using it? There may be a lot of practical DHCP server configuration tips, you usually have not noticed, let's look at it together!

modify gateway and DNS server

1 Modify the gateway address

Due to the need, often have to modify some of the LAN gateway and DNS server addresses. In fact, the configuration of the gateway and DNS server is integrated in the DHCP server, but everyone usually only notices its dynamic IP address allocation function, ignoring the others. Since the default gateway and DNS server can be configured in the DHCP server, it is very simple to modify the default gateway and DNS server used by the client, which can be done in the DHCP server.

In the DHCP Manager window, expand the scope, select Scope Options, and the router and DNS server entries are displayed in the right frame. Double-click "Router" to bring up the "Scope Options" dialog box (Figure 1). After selecting the original gateway IP address in the Default Gateway list box, click "Delete", and then enter the new gateway IP in the "IP Address" field. Address, click the "Add" button, and finally click the "OK" button to complete the modification of the default gateway. The modification method of the DNS server is the same, so I won't go into details.

Bundling IP Address and MAC Address
In order to prevent illegal use of IP addresses, network administrators use various means to bundle IP addresses and MAC addresses. One of them is to use a DHCP server. It is also integrated. Binding function.

● Finding the client MAC address
To use the DHCP server to bind the IP address and MAC address, you must first know the MAC address of the client. On the client side, you can use the "ipconfig /all" command to query the MAC address.

●Quick Binding

Figure 2 Binding MAC Address

After knowing the MAC address of the client, you can perform IP address and MAC on the DHCP server. The address is bound. Open the DHCP Manager, expand the scope used by the client, right-click the "Reserved" option, select "New Hold", and the configuration dialog box will pop up (Figure 2). Name the item in the "Reserved Name" column, then enter the IP address to be used by the client in the "IP Address" field, enter the MAC address of the client in the "MAC Address" field, and then in the "Support Type" In the box, select the "Both" option, and finally click the "Add" button to complete the client's IP address and MAC address binding.
Using a DHCP server across subnets
In order to improve network security, a slightly larger LAN is usually divided into multiple subnets. However, the DHCP server can only provide services for the machines on the subnet. It is wasteful to configure the DHCP server on each subnet. How can I make a DHCP server provide TCP/IP configuration services for multiple subnets at the same time?

The author takes the two subnets A and B managed as an example. One DHCP server is configured in subnet A, and there is no DHCP server in subnet B. The following configuration operations are performed on subnet B: Br>

1. Configure Routing
Select a Windows 2003 machine in subnet B and configure it as a router to connect to subnets A and B. Go to Control Panel→Administrative Tools, run the Routing and Remote Access tool, right click on the local server, select Configure and Enable Routing and Remote Access, the installation wizard dialog box pops up, select Custom Configuration, click Next. After one step, select "LAN Routing" and finally click "Finish".

2. Configure Relay Agent
In the Routing and Remote Access window, expand Local Server→IP Routing→General, right click on “General”, select “Add Routing Protocol”, and then select “New Routing Protocol Window”. DHCP Relay Agent", click the "OK" button.

Right-click on the DHCP Relay Agent and select "Properties". The "DHCP Relay Agent Properties" dialog box is displayed. Enter the DHCP of Subnet A in the "Server Address" field of the "General" tab. The IP address of the server, then click the "Add" button, and finally click "OK".
Right click again on the DHCP relay agent, select "Add Interface", pop up the new interface dialog box of DHCP relay agent, select the interface that can access subnet A in the "Interface" box, that is, connect For the NIC of subnet A, click the "OK" button. Then in the pop-up "DHCP Relay Properties" dialog box, make sure that "Relay DHCP Packet" is selected, its relay function is enabled, and finally click the "OK" button. After completing the above configuration, the client of subnet B can use the DHCP server of subnet A.

Tip: The relay agent is a small program for relaying DHCP/BOOTP messages between DHCP clients and DHCP servers that are not in the same subnet. Configure this Windows 2003 machine as a DHCP relay proxy server. . Thus, when the client of subnet B makes a request, the relay agent forwards the request to the DHCP server of subnet A, and then forwards the TCP/IP configuration information returned by the DHCP server to the client of subnet B.