Read about Consistent Hashing and write a one page report:

• Karger, D.; Sherman, A.; Berkheimer, A.; Bogstad, B.; Dhanidina, R.; Iwamoto, K.; Kim, B.; Matkins, L.; Yerushalmi, Y. (1999). “Web Caching with Consistent Hashing”. Computer Networks 31 (11): 1203–1213.
• http://people.csail.mit.edu/karger/Talks/Hash/