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DHCP

Understanding what the DHCP, dynamic host configuration protocol means, and how it works.

dynamic host configuration protocol

DHCP – dynamic host configuration protocol | Image by Gerd Altmann from Pixabay

Have you ever wondered what is DHCP and how it works? Well, this article is for you. The IP address can be set manually or dynamically for the host in any network. On a small home network with 2 or 3 computers, we can assign IP addresses manually. However, imagine a network with hundreds of computers, and you need to assign all the IP addresses. It could be a nightmare for network administrators! No two hosts can have the same IP address, and manually assigning an IP address can cause errors and confusion. To resolve this problem, DHCP is required. DHCP is required to simplify the assignment of IP addresses on the network. Let’s learn more about DHCP in this blog.

Dynamic host configuration protocol:

The dynamic host configuration protocol refers to network protocol management that assigns dynamically an IP address among other information to each host on the network so that it can communicate effectively. DHCP automates and centralizes the allocation of IP addresses, simplifying the work of the network administrator. Also, DHCP assigns the host to subnet masks, Domain Name Server address, standard gateway, and other configurations. This makes it easier for the network administrator.

DHCP components:

The DHCP server: usually a server or router containing network configuration information.

Its client: this is the endpoint that retrieves configuration information from the server as it does with any computer or mobile phone.

DHCP Relays Agent: If you have a single DHCP server that refers to many local networks, the DHCP relays agent for each network forwards DHCP requests to the server. This is because dynamic host configuration protocol packets cannot be sent through the router. Therefore, the relay factor is required for DHCP servers to process the request from all networks.

IP address pool: contains a list of IP addresses that can be assigned to a client.

Subnet mask: informs the host of the network on which it is currently operating.

Rental period: this is the period during which a customer’s IP address is available. After this time, the customer must renew the IP address.

Gateway address: The gateway address tells the host where the gateway should connect to the Internet.

How does DHCP work?

DHCP works at the application level to dynamically assign the client’s IP address. This is done by exchanging a series of messages called DHCP transactions or dynamic host configuration protocol conversation.

DHCP Discovery:

The DHCP client sends messages to discover the DHCP servers. The client computer sends a package with a default broadcast destination of 255.255.255.255 or the specified subnet broadcast address if configured. 255.255.255.255 is a private broadcast address, which means “this network”: you can send a broadcast packet to the network to which you are connected.

DHCP offer:

When the DHCP server acquires a DHCP discovery message, it offers or provides an IP address (pool of IP addresses) to the client by sending the message DHCP offer to a client. The DHCP offer messages containing the IP address proposed for the DHCP client, the IP address for the server, the MAC addresses of the client, the subnet mask, the standard gateway, the DNS address, and the information of rental.

DHCP request:

In most cases, the client can receive many DHCP offers due to the presence of many DHCP servers in the network (this fault tolerance is provided). If a server’s IP address fails, the other servers can provide a backup. However, the client accepts only a DHCP offer. In response to the offer, the client sends a DHCP request in which a DHCP server requests the specified address. All other IP addresses provided by other DHCP servers are brought back to the set of available IP addresses.

DHCP acknowledgment:

The server then sends an acknowledgment to the client to confirm the DHCP lease to the client. The server may send another configuration that the client could have requested. At this stage, the IP configuration is complete, and the client can use the new IP parameters.

How does DHCP facilitate this?

The DHCP server contains an address pool for a device to create a valid network connection. Basically, the range or range of IP addresses to which devices receive their address is primarily determined.

The second reason that DHCP has the advantage is that many devices can connect to a network for a period without requiring a set of available addresses. Suppose 20 addresses specified by a DHCP server. Devices 40, 80, or 100 (or more) can connect to the network if more than 20 simultaneously use one of the available IP addresses.

Commands such as ipconfig return various IP addresses to your computer over time when using DHCP, because these addresses are provided to the computer network for a certain period, also known as the rental period. A device with a manually assigned IP address does not need to be on the same network as devices that dynamically receive its IP address. Manually assigned IP addresses are also known as static IP addresses.

Benefits of DHCP:

It is easy to implement, and automatic assignment of IP addresses means a specific IP address.

The manual configuration of an IP address is not necessary. This saves network administrators time and effort.

There is no duplicate or invalid IP assignment, which means there is no IP address conflict.

This is a great feature for mobile users, as new valid configurations are automatically retrieved when their network is changed.

Limitations of DHCP

Since DHCP servers do not have a secure client authentication mechanism, any new client can join the network. This poses security risks because unauthorized clients receive an IP address from unauthorized clients, and an IP address is exhausted.

A DHCP server can be a point of failure if the network has only one DHCP server.

Conclusion

The host configuration dynamic protocol is a very important and essential network service that you should use. As a system administrator or network administrator, it helps you interact with clients by assigning, tracking, and reassigning IP addresses. When you leave the administration, you just must stay in touch with your server in case of problems and check the parameters instead of working with your clients.


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