More than storing a huge volume of data in Datacenters, protecting them from threats is a major concern in our heterogeneous networks. From local host to cloud, finding a space to store data was the issue in the earlier whereas retrieving by the right person is the issue in the later. But in both the scenarios, protecting the data from illegal use and unethical access is dispute. Access to a sensitive data like bank account details, medical records and defense data must be restricted. Mere access privileges cannot serve the purpose. Identify the user before allowing him/her to access the data. Authenticating the user and authorize him to access the data every time could control the illegitimate accesses. This paper analysed the wide-range of authentication mechanisms irrespective of the networks. © 2016, Research India Publications.