Mobile Ad-hoc NETworks (MANETs) are dynamic in nature. Because of its dynamic nature of its network infrastructure, MANETS are highly vulnerable to attacks. Among these attacks routing attack has considerable attention, since it could cause most destructive damage to MANET. In existing system, binary isolation and DRC techniques are used to isolate the malicious nodes. However, binary isolation leads to unexpected network portioning and DRC is associative and non-weighted. In this paper, the authors proposed adaptive risk-aware response mechanism with an extended trusted center, where a risk-aware approach which is based on an extended Dempster-Shafer mathematical theory of evidence introducing a notion of importance factors.