DHCP Lease time behaviour

Question

Hi all,

Just want to confirm the behaviour of DHCP server and its lease time.

Scenario: Machine connected and got 10.10.10.1 IP address.

Question: If lease time is up and the machine is still active, will it disconnect and get a new/different IP address or DHCP Server will extend the lease time for it?

Thanks in advance!

Answer 1

Hello,

In the scenario you described, if the DHCP lease time is up, and the machine is still active (meaning it is still connected to the network and requesting to renew its IP address), the DHCP server will typically attempt to extend the lease time for that specific IP address.

Here's a step-by-step explanation of what happens when a DHCP lease time is up:

DHCP Lease Expiration:

When a machine receives an IP address from the DHCP server, it is associated with a lease time. This lease time specifies how long the IP address is valid for that particular machine.

Lease Renewal:

Before the lease time expires, the machine will attempt to renew its IP address by sending a DHCP renewal request to the DHCP server.

DHCP Server Response:

The DHCP server receives the renewal request and checks if the lease time for that IP address has expired. If the lease time has not yet expired, the DHCP server will respond with a DHCP ACK (acknowledgment) packet, effectively extending the lease time for that IP address.

Lease Extension:

The machine receives the DHCP ACK packet and updates its lease time. It continues to use the same IP address as before.

Lease Expired:

If, however, the machine fails to renew its IP address before the lease time expires, the DHCP server will treat the IP address as available and can assign it to another device when requested.

In most cases, the DHCP server will try to maintain the IP address assignment for active machines by extending the lease time as long as the machine remains connected and actively requests lease renewals. This behavior allows devices to retain the same IP address as long as they are consistently present on the network and actively renew their leases.

However, it's worth noting that the exact behavior can depend on the specific DHCP server implementation and its configuration. Some DHCP servers may have different default settings or administrator-configured policies that could impact lease renewal behavior. As such, it's essential to consult the documentation or configuration settings of the DHCP server in use to understand its specific behavior in relation to lease times and renewals.

I used AI provided by ChatGPT to formulate part of this response. I have verified that the information is accurate before sharing it with you.

Hope this resolves your Query !!

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