As of late, botnets are the most radical of all digital attacks and turning into the major issue towards cloud computing. Botnets are the system of various traded off PCs and/or cell phones. These gadgets are contaminated with vindictive code by botmaster and controlled as gatherings. The assailants utilize these botnets for criminal exercises, for example, DDoS, click extortion, phishing, spamming, sniffing activity and spreading new malware. The main issue is how to recognize these botnets? It turns out to be all the more fascinating for the analysts identified with digital security? This focuses us to compose an audit on botnets, its architectural structure and detection techniques.