Yes, Mobiles assign dynamic ip address to users, and some old PC's connected via modem also assign dynamic ip's but proper Broadband, Triband Fast Internet Connections assign static ip address to it's users.
And limiting accounts per user is not an issue in this game. No rule specifies that. Even i have 2 accounts, and i play accounts of 3 other people also. LOL.
But i don't mind leaking that out, because i don't misuse any of those.