The routing table for Router-B shows a static default route (S* 0.0.0.0/0) that forwards all traffic for unknown destinations out of the GigabitEthernet1 interface. While syntactically valid, specifying only an exit interface on a multi-access broadcast medium like Ethernet is incorrect and inefficient. This configuration forces the router to perform an ARP lookup for every destination packet, which can cause high CPU utilization and routing instability.

The correct method is to specify the next-hop IP address. The link between Router-B and Router-C is the 172.16.27.4/30 network. Router-B's GigabitEthernet1 interface has the IP address 172.16.27.5. Therefore, the IP address of the next-hop router (Router-C) must be 172.16.27.6. The solution is to remove the faulty static route and replace it with one that points to this specific next-hop IP address.

Cisco Systems, Inc. (2023). IP Routing: Static Routing Configuration Guide, Cisco IOS XE Cupertino 17.9.x. "Static Route Next-Hop Options" section. The guide specifies: "On a point-to-point interface, you can configure a static route that points to the interface. However, for a broadcast interface, such as Ethernet, it is recommended that you configure a static route with a next-hop address." This directly supports correcting the provided configuration.

Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. In Chapter 5, Section 5.1, "Introduction," the concept of a forwarding table is detailed. The forwarding table's function is to map destination network prefixes to an outgoing interface and, crucially, the next-hop router's address for that link. This fundamental principle underscores why specifying the next-hop IP is the standard and correct practice.

Odom, W. (2019). CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide. Cisco Press. Chapter 6, "IP Routing," discusses static route configuration details, explicitly warning against using only an exit interface on multipoint interfaces and recommending the use of a next-hop IP address to ensure a single, efficient ARP process for the next hop.