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Comment by ams6110 | Hacker News Reader

Apple devices seem to aggressively cache the last known IP address on each wireless network, rather than issue a new DHCP request.

At home this results in duplicate IP addresses when the kid with the iPhone gets home after being away and meanwhile another device has started using that IP address. This tends to bork up the entire network on my cheap Netgear router and I usually have to reset it at that point.

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This might explain what I've seen, which is that whenever I go home for the weekend and join my parent's wifi it somehow screws up the internet for everyone else in the house.

Naive question...why does that mess with the network? Your router has the correct MAC <-> IP mapping, and iPhone kid is the only one losing out.

Not sure but the correlation of Apple device walking in the door and entire home network hanging is pretty consistent.

I presume the router periodically issues "who has 192.168.1.10" or whatever and upon getting responses from two different MAC address just gives up.

It should be noted that many routers (my Netgear not being an exception) reserve private IP's for saved MAC addresses, which makes this a non-issue. Every device on my LAN has a static private IP (I haven't used my full address space yet, so curious what will happen when I do).

I believe most of them also derive IPs from MAC addresses because I always get the same addresses, even with the routers NVRAM set to read-only and different OSes

Aren't there TTLs on those leases? Without have read up on it now, I would assume that if the lease is given with a 24h day the device is in its right to assume it can re-use that IP address in the 24 hours to come?

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