DHCP Lease Time

If you’re wondering about DHCP lease time, how to find out what it’s the DHCP lease time on your device, or to learn basics about DHCP overall, explained in simple and understandable terms with easy-to-follow instructions, you’ve come to the right place.

This article will explain what a DHCP protocol is, what a lease time is and where to find it on most common operating systems, how to change the DHCP lease time, and whether you should change it.

In addition, we will explain how to reserve an IP address for a specific device and when is that a good idea. So, let’s take it from the top.

What is DHCP?

DHCP stands for Dynamic Host Configuration Protocol. It’s a fancy, IT way of saying it’s a protocol that leases temporary IP addresses to all devices on the network.

An IP address and MAC address identify every device on the internet. You could say that an IP address defines the location of a specific device on the network, and a MAC address is a personal ID of that device.

While the MAC address is unique to each device (network adapter) and given during the manufacturing process, the IP address is a different story.

Currently, internet communication is based on a set of protocols called IPv4. This set of protocols uses 32 bits to generate IP addresses. Thirty-two bits can generate around 4,3 billion individual IP addresses. While that was plenty back when IPv4 was created, it is not nearly enough to assign an IP address to each device connected to the internet nowadays.

So, there was a need to develop a solution to this problem while the IPv6 was under development to serve as a stop-gap, and one of those solutions is DHCP. 

Before this protocol, every device had to be assigned a public IP address, which used a lot of IP address pool.

DHCP assigns private IP addresses to the computers and other devices within the network so that the entire network can be connected to the internet using only one precious public IP address.

It does it by leasing, i.e., temporarily assigning IP addresses to all connected devices. The DHCP servers handle all things regarding DHCP protocols. They can be a separate device for large network applications or built-in into the router for small offices and homes. 

Another benefit of using DHCP is that it relieves the users from setting up all network parameters such as default gateway, subnet mask, DNS server, etc. When you are using DHCP, it is all done automatically. 

You can find out all you need to know about DHCP, explained in plain language, in the video below.

DHCP Explained – Dynamic Host Configuration Protocol

What is DHCP Lease Time?

DHCP lease time defines how long the assigned private IP address will stay with the device before it is renewed or taken back. It is usually displayed in seconds. After a predetermined period, if the device doesn’t signal that it is online and asks to continue using the assigned IP address, the DHCP server will take back that IP address and assign it to a different device if needed. 

Small office and home routers usually have an IP pool of around 250 IP addresses. For home applications, that is plenty but imagine using the same router in a restaurant or cafe with dozens, if not hundreds of users constantly coming and going. Without DHCP, that address pool would soon be exhausted, and the network would be inaccessible for new users.

How Does the DHCP Lease Work?

Whenever a new device connects to the network, a DHCP server leases an IP address to that device for a predetermined period.

A halfway through that period, the device will request to renew the lease and get an extension. If the device doesn’t ask for renewal and the lease period expires, the IP address goes back to the pool and can be leased to a different device.

How to Change DHCP Lease Time?

While you can find out the current lease time on your computer or other devices, you can’t change that unless you have administrator access to the router. 

If you do, log in to the router’s admin panel using the administrator username and password, and look for DHCP settings. It is usually within LAN settings. Find an option called DHCP lease time and change it to the desired value. Once you’re done, save the changes and restart the router.

Should You Change DHCP Lease Time?

The answer to this question depends on the quantity, type, and the number of users. For example, an average home with four to five occupants will need twenty to thirty IP addresses from the pool of 200-250. If this is your situation, you don’t need to worry about lease time. Any setting will work, and you can even set it up to a very long one since most of the network devices won’t frequently change.

However, suppose you’re running a coffee shop or other small business with high user frequency. In that case, you should consider reducing a lease time, so you don’t run out of available IP addresses before the leases expire. 

DHCP and IP Address Reservations

As we mentioned more than a few times throughout this article, DHCP is awesome. Still, there are some devices and instances where you want the IP address to be permanently assigned to a specific device.

If you have a network shared printer or networking equipment, all of them need to have a permanent IP address to function properly. 

Also, if you are gaming on a gaming console, it would be much easier to change the NAT type if you assign a permanent IP address to that console.  

You can do this by reserving an IP address and assigning it permanently to a specific MAC address.

To do this, log in to the router’s admin panel and check the list of connected devices. They are usually listed in a Status section. There will be a name of the device, MAC address, currently assigned IP, online status, and other info.

Locate the device you wish to assign a permanent IP address to and write down the MAC address and current IP address.

Now go to the DHCP section and look for static IP configuration, IP address reservation, or similar options.

Once there, click on NEW or ADD, depending on the router’s make and model, and enter pieces of information about MAC and the IP address you found on the status list.

Save the settings and exit.

If this is a PC you are assigning a static IP address to, please update the network setting to match the IP address you gave.

From this point on, the device you listed will always have the same IP address and won’t be under the lease.

Summary

DHCP is a great way to preserve IP addresses and make it easy for average users to connect various devices to the network.

DHCP lease time determines for how long the IP address will be assigned to a specific device. If the device doesn’t ask for renewal, the leased IP address will be retrieved and assigned to a different device when needed.

To change the lease time, you need to log in to the router’s admin panel, find DHCP settings (usually in the LAN section), and set the lease time to a period that suits your needs.

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