In recent years we have realized a rapid development regarding the Internet of Things (IoT). Its goal is to interconnect all possible devices to the Internet and to enhance these physical objects by new functionalities. In this way a user's life standard shall be improved. Regarding the application of Internet of Things concepts, there are some commonly known types of an IoT architecture which can provide different technical opportunities. However, comparative studies on Internet of Things architectures are rare. To relieve the difficulties of establishing a single universal IoT architecture, we describe some well-known architectures and compare these proposals with a special regard to important security aspects. A major focus is devoted to methods repulsing Denial-of-Service attacks. We compile a set of criteria that support network administrators in their decision-making processes with regard to a considered specific IoT scenario and its solution. The goal is to fit optimally to the requirements of these solutions. Finally, the proposed approach is illustrated by three already deployed IoT systems and a comparison of their related architectures and functionalities is presented.