Exam N10-008 topic 1 question 403 discussion

Asymmetric routing occurs when the forward and reverse paths of the network traffic take different routes. This can lead to varying delays and performance issues. In this case, the measured delay of 18ms is higher than the expected 6ms for the MPLS link but lower than the expected 30ms for the VPN connection. Checking the routing tables on both sides will help identify whether the traffic is taking the expected path in both directions. Checking on the partner network for a missing route pointing to the VPN connection, running iPerf on both sides to confirm the delay that is measured is accurate, & checking for an incorrect VLAN assignment affecting the MPLS traffic do not point to an issue that would cause the middle speed traffic.

Asymmetrical routing is the most likely cause for the WAN instability. When two different routing protocols are used, like OSPF and EIGRP, it can cause asymmetrical routing, which results in traffic being routed differently in each direction. This can lead to instability in the WAN. Being dual link, traffic can be transferred incorrectly between the 6ms & 30ms side which can cause a split that will cause slowdown in & potential packet retransmissions during network activity.

Asymmetrical routing is the most likely cause for the WAN instability. When two different routing protocols are used, like OSPF and EIGRP, it can cause asymmetrical routing, which results in traffic being routed differently in each direction. This can lead to instability in the WAN. A CDP neighbor change, a switching loop, or an incorrect IP address are not likely causes for WAN instability. Being dual link, traffic can be transferred incorrectly between the 6ms & 30ms side which can cause a split that will cause slowdown in & potential packet retransmissions during network activity.

Given the scenario described, the action that will MOST likely point to the root cause of the issue is: A. Checking the routing tables on both sides to ensure there is no asymmetric routing Asymmetric routing occurs when the forward and reverse paths of the network traffic take different routes. This can lead to varying delays and performance issues. In this case, the measured delay of 18ms is higher than the expected 6ms for the MPLS link but lower than the expected 30ms for the VPN connection. Checking the routing tables on both sides will help identify whether the traffic is taking the expected path in both directions. While options B, C, and D are valid troubleshooting steps, checking for asymmetric routing is particularly relevant to the described scenario and can help pinpoint the root cause of the performance issue.

The answer is whatever DJ says it is.

Just evil question that confuses whether they want to test the trouble shooting theory (Identify the problem, Establish a theory, Test the theory, etc) or the fact that the issue indicates the root cause that is assymmetric routing. Should I jump into conclusions or first test with iperf.