Rite of Passage
Ace Books 
Synopsis: Mia Havero lives on a giant starship [A back of the envelop calculation shows the volume of the ship is on the order of 10,000 cubic kilometers]. Originally built to ferry colonists from an overcrowded Earth to colony worlds, after Earth’s self-destruction, the ship’s crew put it and its seven sister ships to use as living quarters and a base of power over the less advanced colonies, with whom they trade carefully hoarded information for resources. The Ships tolerate no misbehavior from colony worlds: around twenty of the colony worlds have been ‘morally disciplined’, wiped out from space.