Which of the following is a networking topology concept used when placing publicly accessible hosts on a network?

A VPN (Virtual Private Network) creates an encrypted tunnel for secure remote access between endpoints and is not a network placement topology for publicly accessible servers.

PAT (Port Address Translation) is a variant of NAT that maps multiple private IPs to a single public IP using port numbers - it is an address translation technique, not a hosting topology.

A VLAN (Virtual LAN) provides logical segmentation of a network for traffic isolation and management but is not the named topology concept used specifically for placing publicly accessible hosts.

A DMZ is a network zone positioned between the public internet and the internal private network, providing a controlled and isolated area where publicly accessible servers such as web servers and mail servers are placed. Firewalls on both sides of the DMZ enforce traffic boundaries, ensuring that external users can reach hosted services without gaining direct access to internal systems. This topology is the standard architectural pattern for hosting public-facing resources securely.