Final answer:
The true statement about virtual networks is that they are configured through software. Virtual networks are subject to network policies and firewall rules, and they are not inherently accessible from the internet without proper configurations.
Step-by-step explanation:
The question is asking for the truth about how virtual networks operate and the options provided give different scenarios on their configuration, accessibility, and interaction with firewall settings. The correct statement is:
A. You configure virtual networks through software.
Virtual networks are managed via software configurations within the host system or through management tools designed specifically for virtual environments. Unlike physical networks, they do not require hardware for configuration. As for the other options:
B. This is not necessarily true. A virtual network does not inherently accept network traffic on all ports by default; it is subject to the network policies and configurations set by an administrator, including firewall rules that control traffic.
C. This is also false. Virtual networks are not automatically reachable from the internet. Their accessibility is dependent on the network configurations and whether or not the virtual network has been exposed to the internet through intentional configurations such as port-forwarding, NAT, or placing them within a DMZ (demilitarized zone).