Defending against virus attacks in network is a vital part of network security. With the rapid evolution of viruses, its defense mechanism has also been evolved over the years. But given the diversity and complexity of virus propagation and its attack behavior, no defense mechanism is equipped fully to protect the network from such attacks. Several antiviruses are available in the market. But none can give full proof solution to malicious attacks in communication networks. In this paper we present a mechanism to measure and compare the relative ability of antivirus against various kinds of viruses. We construct a hierarchical structure for different virus defense mechanism. Using Analytical Hierarchy Process (AHP) we construct a pair wise comparison matrix and find the value of corresponding Eigen vectors; we then apply the theory of AHP to calculate weight of each defense index. We validated our technique with an example. Our method can provide a strong reference to design an optimal network security solution.