A DMZ is implemented to host public-facing services while reducing direct exposure to the internal trusted network. Web servers, mail gateways, VPN portals, or other externally accessible systems may be placed in a DMZ so internet users can reach required services without being allowed directly into internal resources. The DMZ acts as a controlled buffer zone between untrusted external networks and trusted internal networks. Destination NAT may be used with DMZ services, but provisioning external zones for NAT is not the core reason. SD-WAN departments is not a valid DMZ purpose. Communication with other organizations may occur through public services, but the security purpose is controlled exposure and internal protection. DMZ design supports segmentation, firewall policy, logging, and containment. If a public-facing server is compromised, proper DMZ controls reduce the attacker's ability to pivot into sensitive internal systems. Reference/topics: Network Security 3.1, zone segmentation; Network Security 3.2, firewall policy enforcement.