Dynamic Host Configuration Protocol, which assigns an address each time a new computer joins the local network...it was said in lecture 6 but when i run internet from my phone cellular network then does it also have a unique IP address or all phones accessing internet from the same network have same IP address like the router does?
They do change frequently depending on if you switch connections; say from data to wifi or reverse. If a phone is connected to a certain NAT router it would obviously assume its IP address. The switch from cell tower to cell tower is handled a little more transparently, however, and that really depends on your provider. You could get a whole new IP from a disconnect (complete loss of signal), although some carriers might hold onto that IP for some number of minutes. I would advise you to do a little research of this on Google perhaps because there is more to learn whereas I just skimmed the essentials.