Comment by pauljara
2 days ago
I was trying to determine if a lease expired, if my router would immediately try to lease that same IP out to another machine on the network. It felt like it cached an expired lease mapping and would try to keep that old IP un-leased in case the original machine to which it was mapped came back online. I was just trying to better understand the behaviour.
Did you want certain IPs to be fixed to certain devices or do you prefer they be randomly allocated?
Neither really, though my ISP's router would allow me to assign IPs by MAC address so they're effectively reserved to a device. The router's web UI displayed a list of devices. I wanted to see if devices would start dropping off this list as soon as the DHCP lease time expired. When they did drop off this list, I had thought they reappeared with the same IP without me explicitly using the reservation functionality. So how was this happening? I figured the web UI might not be showing the full picture of all the data about devices; that the router held records of formerly connected devices beyond the DHCP lease time for some unknown reason.