This paper presents a review of current denial of service (DoS) attack and defence concepts, from a theoretical ad practical point of view. Seriousness of DoS attacks is tangible and they present one of the most significant threats to assurance of dependable and secure information systems, which is growing in importance. Rapid development of new and increasingly sophisticated attacks requires resourcefulness in designing and implementing reliable defences. We focus on providing a both fresh and relevant state of art reference with included different perspectives, such as economicDoS (EDoS) or offensive countermeasures in the cyber space. Considering the elaborated DoS mechanisms and state of art review, our considerations of main challenges are discussed. Directions are proposed for future research, considered required in defending against the DoS threat, which is evolving into a potentially major disruptive factor for global security models on all levels.