: The phenomenal growth and success of Internet has changed the way traditional essential services such as banking, transportation, medicine, education and defence are operated. Now they are being progressively replaced by cheaper and more efficient Internet-based applications. In present era, the world is highly dependent on the Internet and it is considered as main infrastructure of the global information society. Therefore, the availability of Internet is very critical for the socio-economic growth of the society. However, the inherent vulnerabilities of the Internet architecture provide opportunities for a lot of attacks on its infrastructure and services. Distributed denial-of-service attack is one such kind of attack, which poses an immense threat to the availability of the Internet. One of the biggest challenges before researchers is to find details of these attacks because to avoid defamation most of the commercial sites do not even reveal that they were attacked. In this paper...