lucy24 - 10:54 pm on Oct 2, 2011 (gmt 0)
The North American (at least within the US and CAN) IP ranges even though dynamic are fairly consistent (unless the user resets their modem daily). With the majority using broad band connections these days their routers are left on 24/7 maintaining the same dynamic IP for months at a time.
That's not what I'm seeing. A quick riffle through the logs shows my IP address changing every one to two weeks on no discernible schedule. (I never touch the modem, and the cat can't reach its power switch.) If you're on a pretty big ISP, the range can be substantial:
69.111.nnn (change after 9 days)
67.117.nnn (change after almost 4 weeks)
67.122.nnn (change after 6 days)
71.141.nnn (about two weeks so far)
That's on DSL. Similarly I've seen a local cable modem change from 74... to 75... (this is someone I know personally).