Nowadays we see a tremendous growth of the Internet, especially in terms of the amount of data being transmitted and new network protocols being introduced. This poses a challenge for network administrators, who need adequate tools for network management. Recent findings show that DNS can contribute valuable information on IP flows and improve traffic visibility in a computer network. In this paper, we apply these findings on DNS to propose a novel traffic classification algorithm with interesting features. We experimentally show that the information carried in domain names and port numbers is sufficient for immediate classification of a highly significant portion of the traffic. We present DNS-Class: an innovative, fast, and reliable flow-based traffic classification algorithm, which on average yields 99.8% of True Positives and