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How to Renew DHCP Lease (Dynamic Host Configuration Protocol) is a common way to set up network devices so they can talk to each other. Typically you’ll have a DHCP server (like a wireless router), and client machines on the local network (like a Mac, iPhone, PC, etc.) that pull a dynamically assigned local IP address from that server.
This is fine and usually works well, but sometimes you need to renew a DHCP lease. This means you’ll get a new IP address and routing information from the DHCP server. This is a common way to troubleshoot network problems.
It can help fix internet connection problems when a stable wireless connection has been found or when a machine on a network can’t reach the outside world after a broadband modem or router has been turned off and on again.
How to Renew DHCP Lease on Mac
Renew DHCP in System Preferences
- Click on the apple icon on the top left corner of the Menu Bar on the desktop.
- Click on System Preferences.
- Click on the Network.
- Select your network service that provides DHCP
- Click on Advanced
- Click TCP/IP and select Renew DHCP Lease then select OK.
Mac Terminal
- Click on Launchpad.
- Click Terminal.
- Type sudo ipconfig set en0 BOOTP
- Type sudo ipconfig set en0 DHCP
- To check your Ethernet IP address type ipconfig getifaddr en0
What is DHCP Lease?
A DHCP lease is a short-term way of giving an IP address to a network device. When a pool of IP addresses is managed by DHCP, each client on the network only “rents” its IP address. So, a DHCP server can only give out IP addresses for a certain amount of time.
The length of time that the assignment is good for is called the lease duration, and when it ends, the client must stop using this IP address right away and stop all communication on the IP network. If you don’t follow this rule, there’s a chance that more than one device on the network will use the same IP address, which could make it hard to send IP frames to the right device (aka duplicate IP address).
The length of a DHCP lease is measured in seconds. It can be set to “infinite” for permanent leases, which are usually for devices that shouldn’t change their IP address without changing their settings (some IOT, printers or application servers).
How does DHCP Lease Work?
Before we talk about what the best DHCP lease time is, let’s take a look at how DHCP Lease works. Your computer doesn’t have an IP Address when it starts up, so it will need to talk to the DHCP server to get one.
If the computer doesn’t already have an address reserved, it will start a new lease on the IP Address. But if it already has a lease out, it will confirm that it is still available and start the lease again.
- At day 0 it will request a new lease
- During normal operation, the client can use the address
- Halfway the lease time it will try to renew the lease so it can keep the same IP address.
- If renewing failed (DHCP server is offline for example), it will try to extend the current lease with any active DHCP Server.
FAQ
What is the purpose of DHCP lease?
The DHCP server can’t give that IP address to any other clients during the lease time. A lease is meant to limit the amount of time a client can use an IP address. When there are more clients than IP addresses, a lease keeps IP addresses from being used by clients that aren’t being used.
Is it OK to renew DHCP lease?
How to Keep a DHCP Lease Active. If you change your DHCP lease time, you can force any connected devices to give up their current IP lease and get a new one. This will make it possible for any changes you make to your DHCP lease information to take effect right away.
What should DHCP lease be set to?
The default lease time for DHCP is 24 hours, but you can change it to fit the needs of your network. For example, if you’re setting up a lease time for your restaurant’s WiFi network, you can limit it to an hour or two, while a guest office network could have about 12 hours.
How do I resolve DHCP problems?
- The DHCP server service is started and running. …
- The DHCP server is authorized. …
- Verify that IP address leases are available in the DHCP server scope for the subnet the DHCP client is on. …
- Check whether any BAD_ADDRESS listings can be found in Address Leases.