Everyone except me probably already knows this, but I verified today that you don't need a static IP to run a Masternode. Been running a testnet MN today from home, where I have access to two different ISP connections. Started on one with externalip=x.x.x.x:9999 (was even that necessary?) in the conf file, saw it from 'masternode list' on my testnet remote VPS, changed ISP/IP at home, stayed listed as the original IP in masternode list on the VPS, got paid twice, changed back to original IP, got paid again, changed back, got paid again. debug.log periodically shows a message like '2015-01-18 19:57:27 receive version message: /Satoshi:0.10.17.16/: version 70051, blocks=94034, us=184.108.40.206:19999, them=220.127.116.11:19999, peer=18.104.22.168:4735' - the 'us' bit is always correct at the time. No problems at all it seems except only the original IP appearing in the masternode list. My laptop is on 24/7 and switches connection automatically if one goes down, so I might run a main net MN from home for a month and see how it goes. Anyway, just thought I'd share in case there's anyone else unaware of this.