Network security helps prevent overall IT resources inside an organization and application being open to external users. Solution design must plan to secure the network, which can help prevent unauthorized system access, host vulnerabilities, and port scanning.
Solution architects should plan for minimal system exposure by keeping everything behind a corporate firewall and avoiding internet access wherever possible. For example, the web server shouldn't be exposed to the internet instead; only the load balancer should be able to talk to the internet. For network security, plan to utilize an Intrusion Detection System (IDS) and an Intrusion Prevention System (IPS) and put them in front of network traffic.