[thopok]

kad ja odem sa laptopom u hotel npr. i nekim slučajem ip adresa koja mi je ok kod kućne mreže, biva zauzeta, da li server od hotelskog wlana automatski primjenjuje neku drugu adresu ili ja moram kopati po postavkama laptopa i staviti da mi ip adresa bude "automatic"

Zato je bolje koristit DHCP. A ako ga negdje nema:
How to use the Alternate Configuration feature for multiple network connectivity in Windows XP

This feature specifies that TCP/IP uses an alternative configuration if a DHCP server is not found.

If you use DHCP, then you don't have to change your settings if you move your computer to another location, and DHCP doesn't require you to manually configure settings such as Domain Name System (DNS) and Windows Internet Name Service (WINS).