DHCP  What is it? + How it works + Advantages ▷ 2020

DHCP or also known as dynamic host configuration protocol is specialized in simplify and improve the precision of IP addressing. In this way you have the ability to network devices quickly and easily, which has made it an essential method of ensuring that devices can join in networks and are correctly configured.

Therefore, this protocol aims to be able to greatly decrease errors that occur when IP addresses are assigned manually. As well as they have the ability to keep IP addresses individually. In this way, this protocol is one of those in charge of allowing everything work properly, quickly and easily.

Taking into account that this tool is not well known to everyone, nor is it a term widely used by people, here we are going to explain a little more about what are these protocols, what are they for and how they work in computing. To do this, follow in detail everything that we will teach you in this post.

What is a DHCP server and what is it for in computer networks?

What is a DHCP server and what is it for in computer networks?

These servers are those that allow a computer that is connected to a network be able to get your settings dynamically. Furthermore, it is a network protocol which is used in IP networks where a DHCP server is in charge of automatically assigning an IP address and other information to every host on the network. All this allows you to communicate efficiently with others end points.

In this way, the main objective of this tool is to be able to simplify network administration. In the same way it works for power distribute the IP addresses of a network, as well as assign subnet mask, the DNS domain name server address, the default gateway address and many others Settings relevant.

This is how this server has a dynamic IP address list and it goes assigning clients according to these they become free, taking into account at all times what Clients have been in possession of those IPs, how long they have used it and who has been assigned afterwards. This allows customers of a IP network are able to get their configuration parameters automatically.

How does the DHCP protocol interact with the other Internet protocols?

DHCP server It is he who is responsible for distribute IP addresses, so it will be the basis for all DHCP requests so you need to have one fixed IP address. Therefore, in a network you can have only one computer with one fixed IP address. The basic communication system is BOOTP with the UDP frame. When the machine starts up it does not have any information about its Network Configuration, so there is nothing special that the user has to do to be able to get IP address.

In this type of case should be performed transmission technique: This allows can find and communicate with a DHCP server. To do this, the team simply must send a special broadcast packet, an example of this would be “Transmission in with additional information such as the type of request, the connection ports and many other elements. All this through a local network. “

Once the DHCP receive the broadcast package, another transmission packet will respond where it contains all the information that is requested by the client. In this way it can be said that a single package is more than enough for the protocol works correctly. But it must be mentioned that there are different DHCP packet types, which can be issued either from the server or servers to the client or from the client to the servers.

These types of packages are as follows:

  • DHCPDISCOVER: Used to locate servers DHCP available.
  • DHCPOFFER: It is the server’s response to a package DHCPDISCOVER, which contains the initial parameters.
  • DHCPREQUEST: For various customer requests.
  • DHCPACK: It is the response from the server that contains the parameters and the client IP address.
  • DHCPNAK: It is the response from the server to indicate to the client that its grant has been executed, or when it is announces to the client that one of the network settings is wrong.
  • DHCPDECLINE: The client is responsible for announcing to the server that the address is already in use.
  • DHCPRELEASE: In this case the client releases his IP address.
  • DHCPINFORM: The client decides to request the local parameters, you already have an IP address.

How does the communication between client and server work in DHCP?

How does the communication between client and server work in DHCP?

In order to understand this much better, it is necessary to be able to know how the communication between the client and the server occurs or works. Considering that this is where it occurs automatic address assignment Through the dynamic host configuration protocol.

This entire process consists of four steps that we teach you below:

  • In the first step DHCP client sends a DHCPDISCOVER packet to address from address with this named wide broadcast or broadcast, this is where the client establishes a contact with all the other members of the network, in order to locate DHCP servers that are available. Yes there is only one serverThen the configuration is very simple.
  • All servers that listen to requests in port 67 respond to the request of client with a DHCPOFFER packet, which contains a free IP address. The client MAC address and subnet mask, as well as the server ID and IP address.
  • The following will be that the DHCP client select a package and contact the corresponding server in this case DHCPREQUEST. All other servers will also receive this message so that they remain informed of the choice. In accordance with this notification, the client also asks the server for confirmation of the data it has offered. So this answer also serves to confirm parameters assigned previously.
  • Finally, the server takes care of confirm TCP / IP parameters and this sends them from new to customer, this time through the DHCPACK packet. This package contains other data such as SMTP, POP3 or DNS servers. The DHCP client decides to save locally all the data it has received and connects to the network. In the event that the server does not have any most available address, the procthat of the IP would be assigned to another client, to respond with DHCPNAK.

Once all this is done, the assigned address is stored in the server database along with the client’s MAC address. In this way the configuration becomes permanent. Thus allowing the device connects to the network always with that address that has been assigned automatically and that is no longer available to any other customer.

This means that new customers will not be able to receive any addresses if all have already been assigned, even though some IPs are no longer being used. All of this has caused a significant expansion in dynamic directions, and in some cases to Manuela assignment via DHCP server.

Advantages and disadvantages How convenient is it to use these servers?

Considering everything mentioned above in the post, it is very important to know what are the benefits of this protocol and what are its respective disadvantages.

That is why below we are going to show you the benefits and drawbacks that can be achieved when using these types of servers:


  • Count on this DHCP protocol can offer certain advantages, one of them is that it allows you save time in setup, while the connection and disconnection of equipment is done automatically. This will allow you save time configuring IP addresses manually.
  • Other advantages that you can get is the simplification of the Network Configuration, in this case the user simply must connect network cable or connect to WiFi network, so you will not need any kind of knowledge to IP address assignment works by itself.


  • Having this protocol activated can also cause you some inconveniences, especially in safety where they are mostly affected WIFI networks. If found DHCP server enabled, an intruder can have an IP address as soon as you connect. While if there is no said protocol will need manual assignment, and if it has been modified from manually IP range, the hacker or cybercriminal is going to have problems.
  • Another drawback that can be achieved when having DHCP enabled is it going to make it difficult to identify devices in network and the configuration of services that require static IP addresses how would it be open or close ports.

Security on DHCP Servers How reliable and secure are these servers?

One of the things that worries most about using this protocol is the security of servers, especially since it is considered that network security Wifi is usually affected with them. Thus DHCP usually has a weak point and it is that it can reach be easily manipulated. The client usually makes an appeal to everyone DHCP servers who can respond to your request, so any attacker with the necessary knowledge can enter the network.

In a very simple way and impersonate one of them if you had access to it. All that is called Rogue or corrupt DHCP server. The hacker clearly going to try get ahead with your response to the legitimate server, trying like this to get success to be able to send the manipulated parameters. If not sent the gateway then a subnet for each client or responds to all requests with the same IP address.

All this will allow the attacker to initiate a denial of service attack. This will allow it to enter the router using fake data about the gateway and DNS, thus allowing it to be in the position to copy and divert all data traffic. All this is done in order to seize sensitive information as passwords, postal addresses or bank and personal details.

Therefore, when using this protocol it is necessary to implement all the necessary security measures that allow you to enjoy all advantages offered by these servers, without worrying about suffering some of these consequences. For this it is necessary to have a absolute protection about any kind of attack both external and internal, as well as the constant supervision of all processes carried out on the network.

If you have any questions, leave them in the comments, we will answer you as soon as possible, and it will also be of great help to more members of the community. Thank you! 😉

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