The MANET is a collection of mobile nodes such as laptop, palmtop, cell phones, walkie-talkie, etc., form a network. It does not have definite topology. The nodes which comprise MANET will always having moving nature. That is why it could not maintain a permanent topology such as ring, star, bus, and mesh in wired network. In MANET nodes can directly communicate to all other nodes within the radio communication range. If a node could not have direct communication then they can use intermediate nodes to communicate with other nodes. Though each node in MANET will act as host as well as router, the security is a major issue and the chances of having the vulnerabilities are also more.