International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.3 (May 2014) Available online on http://www.rspublication.com/ijeted/ijeted_index.htm ISSN 2249-6149

BotNets are major threat of the current Internet. It is widespread malware and it arises commonly in today‟s cyber crime, which results in serious threats to our network. The compromised computer is infected by viruses, worms, or it has become a target of network attacks only when operational state of a network component is shifted from normal state to abnormal state. Thus, prevention and detection of network systems from catastrophic failures is very important. This paper gives brief idea about Bot, Botnet, life cycle of Botnet and there communication topologies. Paper also includes need of botnet, different methods to detect botnet, existing botnet detection tools and partial listing of major botnets present till date.