MAC randomisation and DHCP pools

Mike Richardson mike.richardson at
Fri Jul 24 09:10:54 UTC 2020


Given Apple's decision to enable randomisation of MACs on IOS devices every
24 hours, I was wondering what effect this would have on DHCP?

For example, if you have a pool of 100 IPs, 50 IOS devices and leases set to
7 days. 

At the moment the same 50 IPs would be assigned each day. Post-randomisation
50 would be assigned on day 1. On day 2, my understanding is that the devices
would REQUEST their previous IPs and be NACKed, then do a DISCOVER and get a
new lot of 50 addresses. What I'm unsure about is what happens on day 3? 'no
free leases', a ping check and reallocation of old addresses or something

Can anyone enlighten me?


Mike Richardson

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