A software development company uses multiple cloud providers to host applications.

In a multi-cloud architecture, traditional perimeter-based firewalls often create "chokepoints" and fail to provide the granularity needed for east-west traffic between microservices across different providers. Adistributed firewallis the architectural solution designed to meet these modern requirements. Unlike a centralized appliance, a distributed firewall is implemented as a software-defined layer that resides close to the workloads—often within the hypervisor or as part of a service mesh.

According to Cisco Security Infrastructure objectives, a distributed firewall allows forcentralized managementof a unified policy that is pushed out to all enforcement points, regardless of whether the workload is in AWS, Azure, or an on-premises data center. This ensuresconsistent security policiesacross the entire footprint. Because the enforcement is decentralized, the solution scales automatically as new cloud platforms or workloads are added. While aTraditional Firewall(Option A) lacks the multi-cloud agility, aZone-based Firewall(Option B) is typically tied to specific physical or logical interfaces on a router, and aHost-based Firewall(Option D) is managed at the individual OS level, which becomes difficult to coordinate centrally at scale. The distributed firewall model aligns with theCisco SAFEarchitectural goal of pervasive security and simplified operations in highly dynamic, heterogeneous cloud environments.

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