The router cannot assign an IP address to the computer.

The reason why an intranet computer can access the Internet through a vro is that the vro is assigned an IP address that gives the computer an identity. If the vro cannot assign an IP address to the computer, then we cannot access the Internet.

1. The failure to allocate IP addresses is due to the fact that most clients cannot log on. After logon, IP addresses cannot be obtained or the access speed is very slow. Use the network command ipconfig in the command prompt of the operating system, the client machine cannot obtain the IP address. Therefore, it is certain that the network cannot be accessed due to this reason and the failure of restarting the computer persists. This proves that the problem is not found on the client, and the switch indicator shows that the status is normal, there is no deadlock caused by congestion, so the problem can only be caused by a router.

2. To understand the cause of the slow down of the DHCP server, we need to understand the working process of the DHCP service. If a DHCP server is deployed in the LAN and the client is set to automatically obtain the IP address, when the DHCP client logs on to the network for the first time, that is, the client finds that no IP address is set on the local machine, it sends a DHCP discover packet to the network.

Because the client does not know which network it belongs to, the source address of the packet will be 0.0.0.0, And the destination address will be 255.255.255.255, and then the DHCP discover information will be attached to broadcast to the network.

3. By default, the waiting time for DHCP discover is set to 1 second, that is, after the client sends the first DHCP discover packet, if no response is received within one second, the DHCP discover broadcast will be performed for the second time. If no response is received, the client will have four DHCP discover broadcasts in total, except for waiting for 1 second for the first time, the remaining three waiting times are 9, 13, and 16 seconds. If no response is received from the DHCP server, the client displays an error message, an error occurred while declaring DHCP discover. Then, based on the user's choice, the system will repeat the DHCP discover process five minutes later;

4. When the DHCP server receives the DHCP discover information broadcast by the DHCP client, it will send the DHCP offer information to the DHCP client, including a rented IP address.

Once the client receives the DHCP offer information, it will use the IP address provided by the server for analysis from the DHCP work process. If the client cannot obtain the IP address, the DHCP server does not respond, or the DHCP server makes a response but the client does not receive the DHCP offer information from the DHCP server. After testing the network cable, the client will not receive the DHCP server response because of network hardware, the result is that the DHCP server does not respond normally.

5. There is a large amount of data interaction between the client and the server. The data occupies a large amount of system resources and network bandwidth, resulting in a slow DHCP server. This leads to a vicious circle, and the network is filled with a large number of repeated requests. These junk information occupies a large amount of bandwidth and forms a network storm. The server needs to transmit a large amount of data, in this way, the network and bus of the server are too heavy. Not only does the operating system process fail to respond to DHCP requests sent by the client in a timely manner, but the computer cannot work normally.

6. Obviously, the overwhelmed DHCP Service causes a fault. To fundamentally solve the problem, you only need to upgrade the server or increase the number of servers to perform their respective duties, so as to avoid excessive server load. A dedicated DHCP server is deployed for the IP Service of the Department, and a dedicated database server is deployed to serve the online examination system. A dedicated File Server is deployed to provide file servers and network cloning services.

This is mainly because the DHCP function is beyond the limit, it will strike like the above vro. We need to pay special attention to this, but for a small network, you only need to purchase a router with good performance, and there is no need for a dedicated DHCP server.