The network security manager of a large corporation is planning to improve the efficiency of the company's security information and event management (SIEM) system. The SIEM system receives data from various sources, including Windows and Linux hosts, switches, routers, and firewalls. To make the data from different sources more consistent and searchable, which functionality should the manager focus on enhancing in the SIEM system?
a. Data Normalization
b. Intrusion Detection
c. VPN Configuration
d. DNS Resolution