You are a security architect and need to design a secure firewall, VPN and IPS solution. Where would be the best place to install IPS in the topology if the internal network is already protected?

Installing IPS on the firewall allows it to inspect all traffic traversing the gateway at a single choke point, covering all connected segments including DMZ and internal networks. This centralized approach ensures uniform policy enforcement and reduces management overhead compared to distributed deployment. It leverages the firewall's existing traffic inspection capabilities to apply IPS signatures to all flows simultaneously.

Installing IPS on each network segment separately is redundant, expensive, and complex to manage when a centralized firewall already handles all inter-segment traffic.

The DMZ hosts publicly accessible services and is a high-risk zone that absolutely requires IPS protection, making LAN-only coverage insufficient.

Placing IPS only in front of the firewall means internal and DMZ traffic is never inspected after passing the firewall, leaving those segments unprotected from threats that bypass the perimeter.