The correct answers are A and B. In SRX chassis clustering, the fab interface is the fabric data-plane link between cluster nodes. Juniper explains that data-plane software synchronizes session state using runtime objects, or RTOs, across the fabric data link, and this fabric link also supports forwarding traffic between nodes when ingress and egress processing occur on different chassis members.

swfab is also a chassis-cluster data-plane-related interface used for Layer 2 switching fabric functionality. Juniper’s Ethernet switching on chassis cluster documentation describes swfab0 and swfab1 as pseudointerfaces created for Layer 2 fabric functionality, enabling switching across the nodes. Option C, fxp1, is wrong because fxp1 is the control link interface used for cluster control-plane communication, heartbeats, and synchronization signaling, not a data-plane fabric interface. Option D, fxp0, is wrong because fxp0 is the out-of-band management interface. The clean separation is: fxp0 = management, fxp1 = control link, fab = routed/data fabric, and swfab = Layer 2 switching fabric. Reference topics: HA Clustering, fab interfaces, swfab interfaces, control link, management interface, data-plane synchronization.