Home Tech What is DHCP Lease Time? How To View and Change It

What is DHCP Lease Time? How To View and Change It

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The DHCP (Dynamic Host Configuration Server) allocates IP addresses to devices that are connected to the server. These IP addresses that are allocated to the devices are not permanent.

The DHCP server gives devices such as your laptops, smartphones, and printers IP addresses when they connect to a local network. The specific IP address is only available to the device for a specific period of time referred to as the DHCP lease time.

This article will focus on DHCP lease time. What the DHCP lease time is, and how it works will be explained. Suggestions on how long to set the lease time to will be given. The steps to take when you want to view, change, or renew the DHCP lease time will also be given. Now let’s dive into explaining what DHCP lease time is.

What is DHCP Lease Time?

The Dynamic Host Configuration Protocol is a network management protocol. A DHCP server automatically assigns IP addresses to computers, smartphones, and other devices connected to the network. Any device connected to the LAN (Local Area Network) must have an IP address in order to connect with other devices or with the internet. 

The DHCP network management saves you the trouble of manually assigning IP addresses to devices on a network. 

The DHCP lease time is the setting that controls how long devices on a network keep their allocated IP addresses. The IP addresses given to a device are temporary, hence the name “lease” time. 

The lease time is the period between the obtaining and the expiration of an IP address by a device. After its expiry, the device releases it’s IP address and can then request for a new one. The previous IP address is free to be assigned to another device.

It should be noted that DHCP runs on your router and not on Windows or Mac. The lease time cannot be changed unless you have access to the router configuration interface.

Note:- DHCP not running on the windows means windows 10 client os, not the Windows server. Most of the organizations that are in the domain-client architectures are using the Windows server as a DHCP server.

DHCP lease timing for the windows DHCP server is 8 Days by-default that you can change it in the DHCP scope.

dhcp lease time 1 1

How Does DHCP Lease Time Work?

It is known that when you power on your device, it doesn’t have an IP address. It has to connect to the DHCP server to obtain an IP address. Once the connection with the DHCP server is done, the server would find out if the device has a reservation for a specific IP address.

dhcp lease time

If the device doesn’t have a reservation for an IP address a new one would be assigned to it. So if you are a visitor and want to connect to the network, your device will be assigned an IP address.

Places like restaurants usually have IP addresses assigned this way to devices connecting to the WiFi. Restaurants and other businesses with numerous businesses will be configured to have a shorter lease time than many offices with fewer visitors.

If you have previously connected to the DHCP server but your lease time has expired, you will be assigned a new IP address when next you connect.

If the device connecting has an active lease, the DHCP server will confirm the availability of the lease and resume. For instance, if the DHCP lease time in your office is eight days, when you try to connect to the LAN in the morning, the server will confirm your reservation and assign the device to its IP address.

In fact, it can be said that the DHCP lease has a life cycle. The first part is the initial lease. When you connect to the server, you have leased an IP address and then the countdown begins.

Halfway through the lease time, it will try to renew the lease so the IP address can be retained. This is done so that your connections or any task you’re performing are not interrupted at an inconvenient time, for instance, when you’re downloading a file.

If the renewal fails, the device will try to extend the current lease with any active DHCP server. 

If the lease time cannot be renewed before it expires, the device will be assigned a new IP address and a new lease will begin.

How Long Should You Set the Lease Time To?

Care has to be taken about how long the lease time is configured for. It is important to manage the lease time properly. You should ensure that about 20% of IP addresses are always available. Also, ensure that lease time isn’t set too long or too short.

If the lease time is set too short, important tasks such as downloads will be interrupted. Also, there would be more DHCP related traffic as devices constantly attempt to reconnect to the network. If the lease time is too long there would be many unused IP addresses that are reserved.

Generally, you can set a lease time of eight days for wired devices such as desktops and printers. These devices don’t usually leave the network and so can have a longer lease. 

Wireless devices such as smartphones and even laptops leave the network often and may not always return to the network for days should be leased for about 24 hours.

Guest networks should be leased for a shorter time. Office guests can be leased for about eight hours, while hotspots usually are not leased for more than an hour.

It should be noted that many devices are benefited by having a static or fixed IP address. This is particularly useful if you set port forwarding to a particular device. Routers, switches and network printers usually have fixed IP addresses. You should allocate such devices a fixed IP address on your network. 

Doing this will save you time and effort. For instance, if you come back from a long holiday, devices that do not have fixed IP addresses will have to obtain a new IP address. This means that if devices like printers receive new IP addresses, they may have to be reinstalled on individual computers.

How To View DHCP Lease Time

If you’ve just connected to a network, and you’re unsure of what the lease time is, you can check.

On Windows 10, you’ll use PowerShell to view the lease time. To open the PowerShell, right-click on the Windows start menu.

Next, select Windows PowerShell (Admin) to launch PowerShell with admin privileges.

powershell

Once the PowerShell window is open, type ipconfig /all.

Doing this would bring a list of all relevant information about your current network connection. This information includes the DHCP lease issue and expiry times.

dhcp lease time

Look for “lease obtained” and “lease expires”. From this, you can calculate the lease time.

DHCP Lease Time

To view the lease time on macOS, you’ll need to open the built-in Terminal app. Click the launchpad then  “other” then “terminal”.

How To Change DHCP Lease Time

You should note that it is not possible to change DHCP lease time in the network settings of your device. This is because the lease time is controlled by the DHCP server (which is usually your router). To change the lease time, you need administrative access to the router to do so.

Open the web browser on your device and type the address of your router. For most routers, it is either 192.168.0.1 or 192.168.1.1. Enter the admin credentials for your router then sign in. On the router web interface, look for an advanced setting category called LAN, and select it.

dhcp lease time

Select the DHCP server tab on the LAN configuration page. Next, find the lease time option. Type the desired lease time (in seconds). The lease time is usually specified in seconds, not minutes, hours or days.

To save the changes, click “Apply”, ” Save” or “Ok”. After saving, your router may need to reboot.

How To Renew The Lease Time

On Windows:

To renew the lease time on Windows, run the Command Prompt or PowerShell commands:

ipconfig/release” and “ipconfig/renew

release

On macOS:

Use the system preferences menu. To do this, tap the Apple icon on the menu bar, then select system preferences.

pre

Next, select Network and choose your network in the left-hand menu.

net

Next press Advanced.

dhcp lease time

In the Advanced Network Menu, choose the TCP/IP tab. Click the renew DHCP lease button to Release and Renew your IP lease.

ren

if you are a command lover like me then you can also view the DHCP lease time on the terminal.

open the terminal by pressing the Command+Spacebar to open the spotlight and enter the terminal and open it.

dhcp lease time 1

First, enter the below command to first know the device

networksetup -listallhardwareports 

currently, I am connected with WiFi and after entering the above command it’s showing me en0 as a device.

dhcp lease time 2

now enter the below command to get the DHCP lease time.

ipconfig getpacket en0

replace en0 with your device name.

dhcp lease time 3

it will show you lease time in the hexadecimal format that you need to convert, no worry visit the https://www.rapidtables.com/, and enter this value.

as you have seen in the below screenshot, I entered the 0x3f480 value in the hex number that converted into the decimal number.

Screen Shot 2020 10 05 at 7.04.09 PM

the decimal number is value in second, if you want to convert this value in hours then just open the google search and enter this value.

dhcp lease time 4

Conclusion

The DHCP server manages connections on your local network. One of the tasks it performs is to assign IP addresses to devices connected automatically. These IP addresses are not permanent, but temporary allocations.

The DHCP lease time is the period in which the IP address is active for a device. The lease time can be changed, and the lease renewed, and this article explains how.

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