Parametric CAD modelling systems requires the successful CAD model creation and modification in the product design phase. It demands persistent identification of topological entities, retrieving faces, edges, and vertexes are done with those entities specific unique names called persistent IDs. Those names should contain their unique properties which would be unambiguous among topological entities. In this paper, we are going to present reviews of existing persistent identification mechanisms and discuss their merits and demerits based on topology based approach, geometry based approach, or a combination of both ones. This review paper tries to define persistent identification mechanism not simply by topology and geometry but by their unique properties like feature orientation based persistent identification, faceIDGraph based persistent identification etc. Previous papers classified the persistent identification mechanism by only the topological or geometrical properties of entities which are too simple to understand the inside merits and demerits of that method. This paper also identifies the advantages and limitations of the current persistent identification approaches while suggesting a new approach should be developed consisting of both topology and geometry based approach. This paper also suggests the future direction of persistent identification of parametric CAD models and their entities.