Cloud computing is an emerging technology that is becoming more and more popular. This is because of its elastic nature i.e. users can acquire or release resources on demand and pay only for the resources they use. Those resources are usually in the form of Virtual Machines (VM's). Elastic provisioning of resources means optimum utilization of resources by avoiding over provisioning and under provisioning of resource. This paper presents a study on Bin packing problem for resource provisioning in cloud. The authors are going to model it as Class Constrained Bin Packing problem (CCBP) where each server is a bin, items are applications.