Which statement best describes asymmetric routing in a network?

• A. All packets must traverse the same path to reach the destination.
• B. Packets may follow different forward and return paths, potentially causing firewall or stateful inspection issues.
• C. Routing must always use equal-cost multipath for reliability.
• D. The return path is always the same as the forward path in software-defined networks.

Answer: (B)

Asymmetric routing occurs when the path taken by outbound packets to a destination differs from the path the return packets follow back. In data center networks, routing decisions and load-balancing can send traffic on one route for the forward path and a different route for the return path. This matters because many devices that track connection state—like firewalls and other stateful inspection appliances—store information based on the specific path or interface the forward traffic used. If the return traffic arrives via a different path, the device may not find the matching state, causing connections to fail or be dropped.

This is why the best description is that packets may follow different forward and return paths, potentially causing firewall or stateful inspection issues. The other statements describe symmetric routing, a requirement for equal-cost multipath, or an always-same return path in SDN, none of which accurately capture how asymmetric routing works in typical networks.