A traceroute shows the path to a destination looping between two routers. What is this sign of?

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Multiple Choice

A traceroute shows the path to a destination looping between two routers. What is this sign of?

A routing loop is happening. When a traceroute shows the path bouncing between the same two routers, packets are being forwarded in circles because the routers’ view of the best path to the destination is inconsistent or unstable. In practical terms, one router thinks the next hop toward the destination is the other, while that router thinks the next hop is back to the first one, so the traffic shuttles back and forth. This looping shows up in traceroute as repeated appearances of those two hops, rather than progressing toward a final destination. Congestion would mostly manifest as increasing delays or jitter, not a repeated two-hop pattern. Packet loss is about drops along the path, and timeouts mean a hop isn’t replying at all, rather than the path cycling. The exact looping pattern is the telltale sign that a routing loop is present.

A routing loop is happening. When a traceroute shows the path bouncing between the same two routers, packets are being forwarded in circles because the routers’ view of the best path to the destination is inconsistent or unstable. In practical terms, one router thinks the next hop toward the destination is the other, while that router thinks the next hop is back to the first one, so the traffic shuttles back and forth. This looping shows up in traceroute as repeated appearances of those two hops, rather than progressing toward a final destination.

Congestion would mostly manifest as increasing delays or jitter, not a repeated two-hop pattern. Packet loss is about drops along the path, and timeouts mean a hop isn’t replying at all, rather than the path cycling. The exact looping pattern is the telltale sign that a routing loop is present.

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