I have written on the topic of cloud-induced transformation of IT in the past. Adapting IT audit and monitoring processes to cloud infrastructure is one of the challenges I come across when it comes to cloud rollouts.
In a 1990s-era data center, everything revolves around hardware and virtual machines. Big, monolithic applications are installed and run on servers. Servers themselves run in the private subnet (secure) or public (DMZ), and they have various security agent software installed to monitor and log everything that goes in and out of these machines.