Refer to the exhibit. The ISP is implementing a new hosting-as-a-service solution for its business customers. Service accessibility must be unique and separate for each customer. The network…

fast-hello under IS-IS improves IGP convergence speed but doesn't directly address MPLS black-holing protection, and BGP multipath 2 enables simple multipath, but additional-paths (in E) offers a more robust solution for path diversity from the BGP perspective.

VRF-Lite provides local route separation but does not integrate with an MPLS core network for full L3VPN services, which the scenario of an ISP hosting solution implies. While BGP address-family VPNv4 is correct for MPLS L3VPNs, VRF-Lite is typically a non-MPLS feature.

Creating a VRF (Virtual Routing and Forwarding) on router R4, likely a PE router, ensures that service accessibility is unique and separate for each customer by maintaining separate routing tables. Configuring it with appropriate route targets (both) allows for controlled import and export of routes, crucial for MPLS L3VPNs.

fast-reroute per-prefix for IS-IS provides advanced, rapid local protection for link failures, which is more sophisticated than the 'basic protection' specified, and mpls ldp sync better fits the 'basic' description for preventing black-holing due to IGP/LDP desynchronization.

The mpls ldp sync command ensures that LDP only advertises labels for prefixes after the IGP has fully converged on an interface, preventing traffic black-holing during IGP reconvergence after a link failure. Integrating BGP additional-paths allows BGP to advertise multiple paths for the same prefix, enabling the provision of 'multiple paths toward the hosting-as-a-service solution' for redundancy and load balancing.