Abstract: The Internet has experienced a tremendous growth in its size and complexity since its commercialization. Internet hosts are threatened by large-scale Distributed Denial-of-Service (DDoS) attacks. DDoS attacks typically rely on compromising a large number of hosts to generate traffic to a single destination, the severity of DDoS attacks will likely increase as greater numbers of poorly secured hosts are connected to high-bandwidth Internet connections. In this study we present the routing instability in the Internet due to the IP Spoofing and analyzed a survey of possible attacks and controlling mechanism available.