Network and information security is a major concern of researchers. Important information can be easily hacked these days. Although, there are various security algorithms available, but still internet world is not secure. Most of the time intruder attacks on a network by creating malicious node. These malicious nodes destroy the network communication or send information to the other server. Sybil attack is one of the major attacks. This paper presents a technique to detect and prevent mobile ad-hoc network from Sybil attack. The proposed technique is implemented on QualNet5.0. The results and graphs are described to evaluate the efficiency of new technique.