The use of the Internet has increased in recent years remarkably. Companies employ the World Wide Web (WWW) to gather, disseminate and interchange information with actual and potential customers, and then Internet Technology seems to be served and applied as a strategic tool and affects strategies and practices of a firm such as Porter's competitive strategies. Many research findings confirm and support being of positive effects of Internet on an enterprise's competitive advantage. In this paper, we will illustrate that enterprises can acquire relational and informational competency through Internet technology, and based on these competencies they can succeed in competitive cyber markets. According to the Internet competencies, Internet marketing strategies can be divided into five categories: Transactional, Profile, Customer-oriented, Relationship, and Knowledge strategies. Choosing and implementing any category of strategies depends on the degree of internet competencies (informational and relational) that a firm has. When both are high, proper internet marketing strategy seems to be knowledge strategies; and when both are low, transactional internet marketing strategies would be the suitable category.