Policy Enforcer is a Junos Space Security Director component that allows updated security policies to be deployed across Juniper SRX Series firewalls, MX Series 5G Universal Routing Platforms, EX Series Ethernet Switches, QFX Series Switches, and third-party network devices1. Policy Enforcer can leverage the DDoS protection feature of Juniper devices to detect and mitigate DDoS attacks on the network. The DDoS protection feature is based on two main components: the classification of host-bound control plane traffic and a hierarchical set of individual- and aggregate-level policers that cap the volume of control plane traffic that each protocol type is able to send to the Routing Engine (RE) for processing2. The DDoS protection feature is supported on MX Series routers and QFX Series switches, among other devices3. Therefore, the correct devices to use for DDoS protection with Policy Enforcer are MX and QFX.

The other options are not correct for the following reasons:

• vQFX is a virtual switch that emulates the QFX Series switches for testing and development purposes. It does not support the DDoS protection feature4.
• vMX is a virtual router that emulates the MX Series routers for testing and development purposes. It does not support the DDoS protection feature.

References: Policy Enforcer DDoS Protection Case Study Protection against distributed denial of service (DDoS) attacks vQFX10000 Overview [vMX Overview]

References:

• [SRX] Behavior of active sessions when modifying a security policy1

= The vSRX is a virtual firewall that offers the same features as the physical SRX Series firewalls, but in a virtualized form factor for delivering security services that scale to match network demand. The vSRX supports Juniper Contrail Networking and third-party software-defined networking (SDN) solutions, which enable dynamic and automated network provisioning and management. The vSRX also integrates with cloud orchestration tools such as OpenStack, which allow for flexible deployment and configuration of virtual machines and networks. The vSRX provides granular security for the workloads that run within the virtual network on the public or private cloud. It supports next-generation firewall capabilities, such as application security, intrusion prevention, user identity, and role-based access control. It also supports advanced threat prevention features, such as malware sandboxing, threat intelligence feeds, and encrypted traffic inspection. The vSRX can protect the network from both internal and external threats, and enforce consistent security policies across the entire network. References:

• vSRX Virtual Firewall | Juniper Networks US
• vSRX Documentation | Juniper Networks
• Understand vSRX Virtual Firewall with Microsoft Azure Cloud