The problem of identifying DDoS (Distributed Denial of Service)Attack is one of the prevalent threats in the field of Internet security. The difficulty lies in distinguishing the attack traffic from the normal traffic, as their attack origin is often hidden. Several techniques are used to detect and identify the source of DDoS attack. One of the most popular techniques in identifying the attack source is the IP traceback mechanism. Different kinds of traceback approaches are proposed with each having its own advantages and disadvantages. This paper presents and evaluates some of the existing and recently evolving IP traceback techniques with respect to their pros and cons.