A SURVEY ON DISTRIBUTED DENIAL OF SERVICE ATTACK AND DEFENCE

In computing, a denial-of-service (DoS) or distributed denial-of-service (DDoS)attack is an attempt to make a machine or network resource unavailable to its intended users.DOS attack reduces the efficiency of the server, inorder to increase the efficiency of the server itis necessary to detect the dos attacks. the reliability and security of the Internet not only advantages on-line businesses, but is also an issue for national security. In today's fast growing of internet usage the security of the data, resources and other confidential files are more important aspects. There are so many types of DDoS attacks occurred by attacker on network.DoS causes serious damages to the services running on the victim. Therefore, effective detection of DoS attacks is essential to the protection of online services. Work on DoS attack detection mainly focuses on the development of network-based detection mechanisms. To meet the increasing threats, more advanced defenses are necessary.