In this paper, the authors deal with possibilities of the network protection against Distributed Denial of Service attacks (DDoS). The basic types of DDoS attacks and their impact on the protected network are presented here. Furthermore, they present basic detection and defense techniques thanks to which it is possible to increase resistance of the protected network or device against DDoS attacks. Moreover, they tested the ability of current commercial Intrusion Prevention System (IPS), especially Radware DefensePro 6.10.00 product against the most common types of DDoS attacks.