How to solve DHCP server faults

When we use a DHCP server, we will inevitably encounter one or more failures. What should we do? We all know that each computer needs an address to access the Internet normally. This address is what we often call an IP address. How can we effectively manage these IP addresses as network administrators? You can set the corresponding IP address, subnet mask, gateway address, DNS address, and other network parameters for each computer, but it is very cumbersome and heavy workload, conflicts often occur in practical applications.

How can we effectively allocate these network parameters? The DHCP Service can help us a lot. It is very efficient to configure the DHCP service on a professional server and allocate IP addresses and other information to all common clients in the network. However, DHCP also brings some problems while facilitating network management. For example, if the network bandwidth is affected, the client often cannot obtain the correct address information or even any information. In fact, we can solve these faults according to certain rules. Today, I will introduce the troubleshooting methods for DHCP faults to readers of IT168.

Before introducing the troubleshooting of DHCP faults, I would like to clarify a few conceptual things for you. Only theoretically enriched can we better understand the troubleshooting ideas described below.

1. What data does the DHCP service provide? The DHCP Service is not omnipotent. It can only provide network-layer parameters, such as IP addresses, MASK addresses, Gateway Addresses, WINS and DNS server addresses. For lower-layer addresses, such as MAC addresses, information cannot be provided. The MAC address is installed in the computer Nic.

2: Can Multiple DHCP servers run simultaneously? The DHCP server sends network information to the client through a broadcast packet. Therefore, if Multiple DHCP servers exist in the same broadcast domain in the same network, each server provides its own network information, resulting in a conflict of broadcast packets on the network. The client does not know which DHCP server to accept. Therefore, Microsoft sets up only one DHCP server in the same broadcast domain network by default, and then sets up or enables DHCP to work.

Third: What is a lease? When configuring the DHCP server, the number of days of the lease will be set. What is the lease? After the DHCP server sends the network information packet to the client, it will receive the reply packet sent back by the client, then, the DHCP server establishes a correspondence relationship between the allocated IP address and the MAC address of the computer received from the client, and stores the correspondence in the lease pool of the DHCP server. Why is this lease pool required? On the one hand, it increases the speed for the next allocation of network parameter information. However, if the client computer corresponding to the MAC address is moved elsewhere or the MAC address changes, if the relationship established above is always stored in the lease pool of the DHCP server, the number of available IP addresses will decrease, and many valid IP addresses will be occupied by Invalid MAC addresses, therefore, Microsoft introduced the concept of lease. Through the lease, we can force all entries saved in the lease pool of the DHCP server to be cleared at intervals, thus preventing illegal MAC addresses from occupying legitimate IP addresses.

Fourth, my client can obtain IP information in the form of 169. 254. *. * from the DHCP server. This sentence is incorrect. Why? Microsoft provides this function in windows, that is, if no DHCP server exists in the network and the local network information of the client is set to automatically obtain the IP address, then the Windows 169 and later operating systems will automatically allocate. 254. *.. Therefore, if you find that your client can only obtain IP addresses like 169. 254. *. *, it means that your DHCP server is not working properly.