Local Area Network Security 249 Some resources provide controlled access to a network; other resources carry sensitive corporate data. Hence the threats posed to these resources do not carry the same degree of vulnerabilities to the network. Therefore, the network access control has to be articulated and applied to each of the components listed, in varying degrees. For example, threats to DNS server pose a different set of problems from threats to the database servers. In the next section we itemize the threats to these resources and specific network access controls. 5. Threats We need to identify the threats posed to the network from internal users as opposed to those from external users. The reason for such a distinction is that the internal users are easily traceable, compared to the external users. If a threat to the data network is successful, and it could lead to loss or theft of data or denial of access to the services offered by the network, it would lead to monetary loss for the corporation. Once we have identified these threats, we can rank them from most probable to least probable and design network security policy to reflect that ranking. From Table 10.2, we observe that most frequent threats to the network are from viruses, and we have seen a rapid explosion in antivirus, antispamware, and spyware and adware