DHCP Lease Time - What should I set it to?

xOne of the settings you may have noticed when setting up a router at home or work is DHCP lease time. If you aren't an experienced IT professional, it is highly likely that you have overlooked this setting altogether, especially if you aren't sure what it does or what value you should assign to it.

The more devices you connect to your internet service, the more important it is for you to understand what this term means, and what settings are most appropriate for your personal or business needs.

What Exactly Is DHCP Lease Time?

A home lease may already be familiar to you. An agreement that permits a tenant to live in a home for a specified period of time is known as a home lease. After that period expires, a new tenant is most likely to move into the home. In the same way that a house or apartment lease works, a DHCP lease time works as well.

DHCP stands for Dynamic Host Control Protocol. It is responsible for assigning IP addresses. Every device that connects to a network must have an IP address; no matter where it is, from your home laptop to your office desktop computer to your smartphones, smart TVs, tablets, and any other connected devices.

IP addresses are similar to home addresses. Each home needs an address in order to receive mail. Any device connected to the internet must have an IP address that identifies it when sending and receiving data. An IP address has two parts - the first and last of a series. In between numbers are reserved for other devices to use on the network.

The DHCP lease time - also known as client lease time - defines how long some devices have a permanent IP address and how long others have a temporary IP address. A temporary IP address is assigned to other devices that do not require a set IP address, such as a visitor using a company's free Wi-Fi. The IP address for the device expires after a set period of time if it is not connected to the LAN server. It is then assigned to another device. It is known as DHCP lease time.

Sound complicated? It's not as complicated as you might think. Let's take a coffee shop as an example. There is free Wi-Fi available at this coffee shop. Due to the fact that most patrons will not be in the coffee shop all day, every day, their device (laptop, tablet, or smartphone, for example) will not need its own IP address. Instead of an IP, a DHCP lease time will be assigned.

As soon as the lease period expires, the IP will be assigned to another device - such as a new customer's smartphone. This way, multiple people can connect to the network without any problems and all of the IP addresses won't be taken.

When to Adjust Your DHCP Lease Time

If you run a business or work in an office where multiple devices are used, you may want to adjust your DHCP lease time, especially if you have employees, customers, or clients who occasionally use their devices. It is likely that a shortage of IP addresses will result if the lease time is not adjusted. You want to make sure that any IP addresses that are being used just temporarily expire after a certain period of time.

If you have many devices on your home network, you may even have to set the DHCP lease time. When devices like your router are used relatively frequently but not daily, a longer lease time may be sufficient.

Finding the Optimum DHCP Lease Time for Your Needs

You may need to experiment with your DHCP lease time settings based on your own needs (or those of your business) in order to get the timing just right.

Typically, the DHCP lease time default setting on most servers is 24 hours. Depending on your server, this may be shorter or longer. From one minute up to a certain number of days, the settings can be adjusted.

Keeping the lease time too short can cause service interruptions. Often, if a busy doctor's office, coffee shop, or other business offers wireless service to its clients and customers, a person will browse the internet on their phone for much longer than one minute. If you set the lease time for just a few minutes, you will encounter interruptions and frustration. Settings may need to be lower than 24 hours if connected devices have a fairly quick turnaround.

If you use devices on a fairly frequent basis in your household and don't have many additional devices connected, you can extend the lease period to several weeks or months. The higher the setting, the fewer the connected devices. The lower the setting, the more connected devices there are.

For an office where users go online on their computers to work, setting a static IP address is recommended. If you use other devices, you must keep several IP addresses open and find the right lease time. The number can be adjusted based on the turnaround times of the different devices that are connected.

Who Sets the DHCP Lease Time?

System administrators often perform this task. Make sure the administrator is aware of your particular needs so they can set the lease time accordingly. There is, of course, a possibility that you may need to make some adjustments, or that your needs may change down the road. Ensure your settings are adequate for the number of devices you're connecting and that your server isn't overloaded.

Final Thoughts

Your server's performance depends on the DHCP lease time you set. You must ensure that this setting is adjusted to keep the server open for new connections if you want to keep your employees connected or your customers happy by providing wireless access.

When setting the lease time, it’s important to remember the following:

• Devices with a fast turnaround require a shorter lease term. Usually, 24 hours is enough, but if it's just not working for you, it may need to be adjusted.
• DHCP lease times can be longer when fewer devices will be connected.
• Static IP addresses should be assigned to devices that are permanently in use.
• Devices that are used frequently but don't necessarily require a static IP can have a longer lease period - think days, weeks, or even months.
• Servers have different default times. Most servers are set to 24 hours, but not all of them are.
• Setting the lease time too low may cause frustration and interruptions. What is the correct setting? Do you have any questions? If you'd like to learn more about changing your DHCP lease times, leave a comment below.