In today's world every user need to transfer data with one-other irrespective to individual's geographic location. Hence a Mobile Ad-hoc NETwork (MANET) has become a vital part of modern communication over wireless network. MANET helps to transfer data without fixed infrastructure and many autonomous nodes vigorously can become part of ongoing communication. Due to this, MANET gets attacked by malicious nodes very easily. Hence secure routing of data packet in MANET is essential task. There are number of attacks the authors have seen in MANET like Denial of Service attack, Jellyfish attack, Warm-Hole attack etc. In this paper, they are concentrating on Black Hole attack in AODV i.e. Ad-hoc On Demand Distance Vector Routing.