DHCP explained, simple and easy | Blog

Sep 28

DHCP explained, simple and easy

What is DHCP? It sounds very complicated but not to worry. Here I have tried to explain it in very simple terms. We all know that every computer has an IP address which is used by the computer networks for communication. Without an IP address the requested information would not be available. Well, understanding what an IP address does, make it easy to explain DHCP. IP address can be assigned to a device in two ways. One is manual assignment and the other is automatic assignment using DHCP.

Most of the cases, automatic assignment happens which is done by DHCP. Now, the abbreviation of DHCP is Dynamic Host Configuration Protocol. Most of the networks use the automatic assignment as it is very easy and more reliable to do so. It is very accurate and consistent too. Usually you need a DHCP server for the automatic assignment to happen. All computers, smart phone etc have a DHCP client which contacts the DHCP server for IP address and gets assigned to one.

Basically, DHCP ensures that every device has a unique and valid IP address and reduces the work of the network administrator in manually configuring them. Imagine a simple scenario where there are letters to be posted to different houses. For it to be posted to different houses, you need an address. This can be imagined in similar scenario where DHCP assigns an IP address for each device.

There is another thing that we need to understand; is that the assignment of IP address is dynamic which means that a computer is assigned with an IP address that is available from a set of IP addresses for that particular network. It also has an expiry date. When IP address is assigned by DHCP it is being leased and the default time of expiry is five days. But there is nothing that needs to be done from our side. It all happens in the background. Even after the expiry of the lease, it is automatically renewed without any user intervention.

We can summarize the understanding of DHCP in the below few steps:

  1. We try to connect to internet through computer or smart phone.
  2. The network requests for an IP address.
  3. DHCP server allocates an IP address in response to the computer’s request.
  4. Computer gets assigned with an IP address and it is confirmed by the DHCP server.
  5. DHCP then updates the network with the IP address that is assigned to your computer.
  6. Computer device accepts the IP address for the lease period.

Whenever you want to access an internet site or web page, your computer requests for an IP address from that particular network’s DHCP server and the DHCP sends back an IP address in response to the request sent.

Without DHCP, internet access seems impossible. As a user, we are not aware of the internal process that takes place when a browser is opened and when we access the internet. It all happens behind the scenes. The assignment and renewal of the lease in case of expiration happens automatically without the user knowledge. This is a wonderful technology which would make the job easier for the network administrator very easy.

Imagine a scenario where there are millions of users accessing the internet with different devices at the same time. If there was no DHCP this would be impossible. Even for a network administrator with few computers, it would be a difficult task to assign an IP address manually and manage them.

DHCP makes life easy for millions of users even when people are not aware of it as it runs in the background.


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