[jrockway]

Is that true? I've worked at two ISPs and we never made an effort to make the IPs ephemeral. (OK, at the second ISP we didn't even have DHCP servers. We made everyone set up every device on their own!)

My current home broadband setup gives me the same IP address for months at a time, across router reboots. Advertisers love it, I'm sure.

[gnfargbl]

That's a great point and very fairly made. For my own ISP (BT in the UK), I get a new IP on each router reboot. I understand that for some others like Virgin, the IP is very stable over long periods.

[naoqj]

For most ISPs making IPs ephemeral is the only solution to the scarcity of IP addresses. You don't want IPs allocated to people who have turned off their routers.

[jhugo]

That doesn't require you to deliberately assign a new IP every time the router reboots, it just requires you to be able to re-use IPs without an active DHCP lease.

In practice customers don't usually turn their routers off for very long, and many ISPs don't have an acute shortage of IPs (those that do have already moved to CGNAT), so it's pretty typical to keep your IP no matter how many times you reboot your router. If I'd leave it off for a month I'd be less sure I'd get the same IP.