What Does DHCP (Dynamic Host Configuration Protocol) Do?
DHCP is a network protocol that allows nodes in an IP network to automatically obtain the configuration parameters.
It is a client/server protocol where a server usually has a list of dynamic IP addresses and assigns it to clients who always know who owns and when that IP is available.
With this protocol, a computer on the network receives the required TCP/IP information from a server or router. Using DHCP is recommended because you will need a lot of time if you try to manually configure the TCP/IP information of all computers on the network.
After configuring a DHCP server in your network structure, you can automatically assign TCP/IP settings to all computers. If there are devices with WiFi hardware on your network, these devices automatically receive TCP/IP information from your server.
A DHCP server-enabled server or router cannot assign an IP address to any computer that has a Static IP address configured on the network.
All devices on the same network can access the IP address pool you have configured on your ADSL Router or a local DHCP server. However, you must enable this service to assign an automatic IP address on these devices.
For example, in this article, we will enable DHCP to get an automatic IP address from ADSL Router on a laptop or desktop computer.
It provides configuration parameters to computers connected to the computer network via TCP/IP protocol and also includes a mechanism for assigning IP addresses.
This protocol was published in October 1993, it is currently documented in RFC 2131. It was last published as RFC 3415.
IP Address Assignment
Without DHCP, each IP address must be manually configured on each computer, and if the computer is moved to another location on another part of the network, a different IP address must be configured. DHCP allows the administrator to centrally monitor and deploy the required IP addresses, and automatically assign and send a new IP if the computer is connected to a different location on the network.
This protocol includes three methods of assigning IP addresses:
Manual or Static Assignment: An IP address is assigned to a particular machine. It is usually used to check the IP address assignment to each client and avoid connecting unidentified clients.
Automatic Assignment: Permanently assign an IP address to a client machine when the request is made to the DHCP server for the first time and the client releases it. It is generally used when the number of clients does not change much.
Dynamic Allocation: It is the only method that allows dynamic reuse of IP addresses. The network administrator determines a set of IP addresses and each computer connected to the network is configured to request the IP address from the server when the network interface card is started. The procedure uses a very simple concept in a controllable time frame. This simplifies the installation of new client machines on the network.
Some applications can update DNS associated with servers using the DNS update protocol created in RFC 2136 to reflect new IP addresses.
It is also an alternative to other network IP address management protocols such as BOOTP (Bootstrap Protocol) but it is an advanced protocol, but both are normally used.
In Windows 98 or later, if the server cannot assign an IP address, a process called “Automatic Private Internet Protocol Addressing” is used.
A DHCP server can provide an optional configuration to the client computer. These options are defined in RFC 2132.
Microsoft introduced DHCP to NT Servers in late 1994 with Windows NT version 3.5. Despite calling it a new function, it wasn’t invented by them.
ISC (The Internet Software Consortium) released DHCP deployments for Unix with version 1.0.0 of ISC-DHCP-SERVER on December 6, 1997, and a version (2.0) that was more suitable for RFC on June 22, 1999.
Cisco: A DHCP server enabled in Cisco IOS 12.0 as of February 1999.
Also, some routers include DHCP support for networks up to 255 computers.
How DHCP Works?
Clients send a request to the DHCP server to obtain their IP addresses. The router can be configured to route packets to a DHCP server on a different subnet. The client application creates a UDP (User Datagram Protocol) package with a target of 255.255.255.255 and requires the last known IP address, although it is not required and can be ignored by the server.
Specifies the server configuration based on the media address of the specified client computer. The server specifies the IP address in the registry given in other parameters.
The client selects the configuration of the packets received from the DHCP Offer. The client once again requests a specific IP address specified by the server.
Sends confirmation and closing message showing the last parameters from the server to the client.
The server responds to DHCPREQUEST with a DHCPACK to complete the startup cycle. The source address is the DHCP server IP address, and the destination address is still 255.255.255.255. The Source Address is the IP address of the DHCP server and the destination address is still 255.255.255.255.
The client sends a request to the DHCP server: the server requests more information than it sent with the original DHCPACK, or to repeat data for a specific use – for example, browsers use DHCP Inform to obtain the configuration of proxies via WPAD. Such requests do not cause the DHCP server to renew the IP expiration time in the database.
How to Enable DHCP on the ADSL Modem/Router using Windows 10
If you are a home user and are using an ADSL Modem, you must enable the DHCP server on your device to assign an automatic IP address to clients on your network.
To enable the DHCP server on the TP-Link W8980 ADSL Router, first enter the default gateway IP address in your web browser, press Enter, and then click DHCP Server.
If this option is disabled, click Enable to reactivate it.
After enabling the server, you can specify which IP addresses to use on the 192.168.1.0 network.
The following screenshot is set to assign values between 192.168.1.100 and 192.168.1.199. After entering the DNS addresses, save the settings.
If you look at the IP addresses assigned by the DHCP server, you can see that the Android phone receives the IP address 192.168.1.100.
Automatic IP Address Settings and Configuration on Windows 10
For DHCP settings, you must configure your network adapter from the Network and Sharing Center.
Follow these steps in order for a computer to obtain an automatic IP address from the server.
The first step in enabling DHCP is to open the Network and Sharing Center. As shown in the picture below, you can immediately access the network and the sharing center after clicking the Wireless icon.
Click the WiFi card or Ethernet card you connected. Then, the WiFi status window will open.
After the WiFi Status opens, click the Properties button. The WiFi properties window will open.
In the WiFi Properties window, select IPv4 (Internet Protocol Version 4) and click the Properties button.
The settings in the following image are statically set. You can enter the desired IP address manually. In this screen, we can enable the DHCP service to get an IP address from the modem.
For TCP/IP settings on Windows 10, select the option in the following image. After selecting the Automatically set IP address, the Obtain an IP address automatically option will be enabled.
After setting the IP settings to be automatically retrieved from the server, click OK to save the settings.
After enabling client service, click on your WiFi card and automatically check the TCP/IP information you receive.
What Happens If DHCP Is Turned Off?
As you can see, the system settings for getting the IP address automatically are very easy. However, TCP/IP settings must configure correctly. If this protocol is disabled, computers on the network cannot automatically obtain an IP address. If you have 150-200 computers in a network environment, you must configure the server. Otherwise, you must manually configure the IP address and other information.
If this protocol is turned off, you must manually configure TCP/IP. In the above steps, you can examine the IP address, Subnet Mask, Gateway, and DNS IP addresses assigned to a computer. If this protocol is turned off in a network environment with 200 computers, the computers cannot receive TCP/IP information and communicate.
To enable the DHCP server on the ADSL Router and configure automatic IP addresses, you can watch the video below and subscribe to our YouTube channel to support us!
In this article, we have examined the steps to configure the DHCP server on an ADSL Modem or Router. And finally, we have assigned an IP address and the necessary information to a networked computer through this service. Thanks for following us!
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