DHCP and lease mechanism?

[baselzind]

let us say I have a dhcp server on my switch and I set the lease to 1 day , what happens exactly when the lease expire for the user pc? does the switch contact the pc and tell it to release the ip and then the switch remove the binding? or is it originally that the pc is told to keep the ip for 1 day then it will release it?

[balaji.bandi]

If the lease expires, if the devices are still online - the end device auto-renew with the same IP address.

if the device is not connected, the lease expired and IP released for the next device will be allocated that IP.

Note: in the case of static IP reservation is a different case.

[baselzind]

so when the lease expire the switch will try to ping the leased device to check if it is online?

[balaji.bandi · Accepted solution]

check how the process works :

https://www.youtube.com/watch?v=STuh2ToipIg

https://lazyadmin.nl/home-network/dhcp-lease-time/

[Kasun Bandara]

PC will ask from switch to renew IP when lease is expiring. if PC didnot renewed it even after expiration time, switch will release that to another PC.

[baselzind]

so always the pc will ask the switch to renew not the other way around? any idea what port and protocol is used?