Introduction: The Eviction Notice
Imagine living in an apartment where your lease ends every Monday at noon. If you don't sign a new contract by 12:01, the locks are changed and you're out on the street. This is effectively what happens with IP Lease Expiry. If your computer or phone fails to renew its lease before the timer hits zero, it is 'evicted' from the network and loses all internet access immediately.
In this guide, we'll explain the 'T1' and 'T2' timers that keep you online and what happens when the system fails.
The Two-Step Renewal
Your computer is proactive. It doesn't wait for the last second to renew. It uses two 'timers' to ensure a smooth transition:
- The T1 Timer (50% mark): At the halfway point of your lease, your computer sends a polite request to the router asking to extend the lease. This is 99% of all successful renewals.
- The T2 Timer (87.5% mark): If for some reason the router didn't answer (maybe it's rebooting?), the computer gets 'brave'. It sends a Broadcast message to any available DHCP server on the network asking for help.
The Result of Total Expiry
If the timer hits 100% and no server has answered, your computer has to stop using the IP address. It will immediately show as 'Disconnected'. It then starts from zero, sending a fresh 'DHCP Discover' message to find any available address. This is why you might see your internet 'drop' for 10-20 seconds before it suddenly comes back with a new number.
Conclusion
Lease expiry is the network's way of recycling addresses. While usually invisible, understanding the process helps you troubleshoot those annoying 'random' disconnects. Check your lease status here.