Wireless Networks is one of the fastest growing technologies. Here the users only need to have a mobile device with a wireless network adapter that negotiates with an Access Point or Base Station. Once authenticated and associated, the user can freely move around within the coverage area of the Access Point without losing data or network connection. On the negative side, these networks tend to have fuzzy boundaries, making it easy for an intruder to capture these transmission signals and also send massive volume of illegitimate traffic and utilize system resources in a way that renders the system inoperable thus denying access to authorized users. This paper is two fold in its description. Firstly, it describes some of the major vulnerabilities associated with wireless networks. Secondly, it demonstrates different methods of achieving denial of service (DoS) attacks as it applies to wireless networks and discusses and proposes different defense mechanisms so as to minimize the attacks.