Use DNS to achieve Load Balancing

Access the enterprise network server
A sharp increase in users, a server
It is difficult to meet the user's access needs. How can we ensure normal user access? There are many solutions, such as using Windows
2000 or Windows
Server 2003 provides the network load balancing service, but the configuration of this service is very complex. However, implementing network load balancing through DNS is a simple method.

Taking Web servers in the enterprise network as an example, I will introduce how to use DNS servers to achieve network load balancing. To increase the access volume of the website with the domain name www.rtj.net, three web servers with the same content are deployed in the enterprise network to provide the same service, but the IP addresses of each server are different. Next, set up the DNS server in the enterprise network to enable the three web servers to jointly undertake the customer's access to the website.

1. Enable Loop

Take Windows Server 2003 as an example. On the DNS server, choose Start> program> Administrative Tools> DNS to go To the DNS manager window. Right-click the DNS Server icon, in the pop-up shortcut menu, select the "properties" option and switch to the "advanced" tab (figure 1) in the "properties" dialog box ), make sure that the "enable loop" option in the "server options" list box is selected.

 

Figure 1

Ii. Add host records

Create a host record in the "rtj.net" area. In the DNS manager window, right-click the "rtj.net" item and select "New Host" in the pop-up menu to enter the "new host" dialog box, and enter "www" in the "name" column ", enter the IP address of one of the Web servers in the IP address bar, for example, 192.168.0.5. Then, click "add host.

Because there are three web servers in the enterprise network and their IP addresses are different, we also need to create two host records with the Host Name "www" in the same way as above, except that their IP address content is different. In this way, the website domain names can be resolved to different Web servers.

The following table lists the three host records in the rtj.net region of the DNS server:

After the above three host records are created (Figure 2), the web server's network load balancing is realized. In this way, when the client accesses www.rtj.net

A domain name resolution request is sent to the DNS server. When the DNS server receives the first request, it will return the first IP address 192.168.0.5 to the client. When the second client requires domain name resolution, the DNS server will return the second IP address 192.168.1.5 to the client. Through such cyclic allocation, client access can be shared to different Web servers to achieve network load balancing.

 

Figure 2

Iii. Optimization of Server Load balancer Functions

A cen usually consists of many subnets. To reduce the data traffic in the network, it is best for a client to access a web server in the same subnet. Although the network load balancing function is implemented, it is not guaranteed that the customer accesses the subnetwork's Web server. In fact, this problem is well solved, as long as you enable the "enable network mask sorting" function of the DNS server.

In the DNS manager window, right-click the DNS server, select "properties" from the pop-up menu, and switch to the "advanced" tab in the Properties dialog box, select the enable network mask sorting option in the "server options" list box. In this way, the client can access the web server in the subscriber network every time.

After the above settings are completed, the DNS server implements the network load balancing function, shares the customer's access to each Web server, and reduces the network communication traffic across subnets, this greatly reduces the communication burden on enterprise networks.