Summary of DHCP server management experience

We know that DHCP is a powerful IP management protocol. The use of DHCP servers is also very common, so we need to understand the content of DHCP server management. I have encountered some problems in DHCP server governance. Although the author has made some efforts to solve the problem. However, I still feel very nervous when I think of a problem with the DHCP server. Today, I will give a brief summary of my problems in DHCP server governance. You may have encountered these questions. Let's discuss them and see if there are any better solutions.

DHCP server management and maintenance considerations: how to back up DHCP server configurations

Network administrators often want to back up configurations of DHCP servers. When the next Server failure occurs, you can use this backup file for rapid recovery without manual configuration on the DHCP server. If some MAC addresses are managed on the DHCP server, reconfiguration is a heavy workload. The DHCP server is also a complicated management system. If the DHCP server fails due to configuration omissions, if a backup file exists, you can use it to quickly restore the original configuration. Therefore, after the configuration is adjusted, even if the DHCP server configuration is backed up, it is undoubtedly a good work habit.

If the DHCP server is an independent server, it is easy. You only need to back up the configuration of the entire operating system, including the DHCP server. However, few enterprises often use an independent server to run the DHCP service, which is too wasteful. Therefore, most enterprise DHCP services and other application services are applicable to one server. In this case, if the backup is used to manipulate the system, the workload will be huge. In addition, subsequent restoration may also cause problems. When the DHCP server is restored, other application servers are restored. Obviously, this is not what we are willing to see. Therefore, this method is not feasible for non-independent DHCP servers.

In addition, we only export the configuration of the DHCP server, without backing up the information of the operating system or other application services. For example, the enterprise's DHCP server is built on Microsoft's 2003. This function is not available in the DHCP server controller window. However, it provides a command to export server configurations and import them to a TXT file. For example, we can use this command: netsh dhcp server export e: \ dhcp.txt all. Export the configuration file of the server to the root directory of the edisk. The file name is dchp.txt. If the server encounters a fault next time, we can use the command to restore it. Command syntax: netsh dhcp server import e: \ dhcp.txt all.

Finally, two suggestions must be made to the network administrator.

First, if you need to adjust the relevant configuration when managing the DHCP server, export the current configuration in time for backup after the test is complete without errors. Only in this way can we cope with the next failure.

Second, not only local backup, but also remote backup. This is mainly to prevent the next hardware failure of the DHCP server, such as a disk error, and timely remote recovery.

DHCP server management and maintenance experience 2: questions about insufficient IP Address Allocation in the address pool

I encountered a headache when I first came into contact with the DHCP server. At that time, when an employee came back from a business trip for a while, he found that his computer could not obtain the IP address. I found through line tests that network communication is normal, and Nic is also working normally. Finally, there is no way. I suspect that it is the problem of operating the system. After the computer is re-installed, the problem still persists. It should be confirmed that it is not the customer's real question. However, other DHCP clients run normally. Why is it true that this host cannot obtain an IP address? Is the problem on the DHCP server?

I checked the running status of the DHCP server and unexpectedly found that the DHCP IP address has been allocated. However, according to my design at the time, when assigning an IP address pool to DHCP, we also considered the balance of over 30%. How can I use up IP addresses? As the user was in a hurry, I had to temporarily add a few IP addresses to solve the user's online problems, and then carefully find the cause.

After some searching, I found that nearly 40 assigned IP addresses are currently inactive. In addition to deducting some computers that do not have a host, it is useless to have more than 30 IP addresses. Seeing this situation, I also know why this fault has occurred. Previously, the company had been operating the ERP system recently. However, this system has high requirements on system configuration. Therefore, we have recently eliminated more than 30 old computers and bought several hundred yuan for employees as benefits. On the DHCP server, the author sets the lease to 200 days. The old computers have been laid off, but the DHCP server has not withdrawn the IP addresses because the lease has not expired. Therefore, after a new computer is connected to the enterprise network, it can only use the new IP address, which leads to saturation of the IP address in the DHCP server. Therefore, when a client wants to connect to the DHCP server to obtain the IP address, the server does not have an empty IP address. As a result, the client cannot obtain an IP address and cannot successfully access the internet.

After learning this lesson, I will learn it later. But for the stability of the IP address, I still did not change the lease of the DHCP server. Later, the lease was set to an infinite number to implement a fixed IP address. In this case, the DHCP server will not take the IP address back. However, when a computer is decommissioned in the future, I will first release the IP address through commands. In addition, you can view the running status of DHCP from time to time and enable unused IP addresses in a timely manner. In this case, similar questions will not be encountered again in future work.

DHCP server management and maintenance experience 3: Common handling steps when an IP address cannot be obtained from the DHCP server

If we find that the network cannot be connected, and the reason is that we cannot obtain the IP address from the DHCP server, there is a set of processing procedures. I will summarize him here as five steps.

Step 1: Open the command line window. If it is Microsoft's operating system, enter the CMD command at the start and running points to open the command line window. In non-Microsoft operating systems such as Linux, there are also corresponding command line windows. For example, in Linux, you can open the command line window through tools and terminals.

Step 2: view the existing network parameter configuration information. You can run the IPCONFIG/ALL command to view the specific network configuration information. Generally, if the IP address cannot be obtained from the DHCP server, the client will assign itself an IP address. Generally, if a client assigns an IP address to itself, it starts with 169.254. Therefore, if you see this IP address, you can determine the customer's real network card and other issues.

Step 3: release existing network parameters. Next, we will use the IPCONFIG/RELEASE command to RELEASE the existing network configuration parameters. After release, we can use the IPCONFG/ALL command to view network parameters. We can see that the IP address is changed to 0.0.0.0. The original network configuration parameters are removed.