Context based searches is always the area which admires by different researchers. Ontology hence, is the way to develop such a semantic web. However, alignment is the way to properly align Ontologies to actually develop the semantic environment. Thus interoperability between different classes can be maintained in order to optimize the context based searches. There exist different methods to map the given Ontologies to make their classes or attributes unique. However, every of them have some drawbacks. We will critically analyze different published methods according to their common attributes.