Exam N10-008 topic 1 question 190 discussion

- If the user's PC has an incorrect subnet mask, it may not be able to communicate with other devices on the network, including the router. This would explain why the user can't access any files, but other users in the branch can. - The fact that the IT engineer can ping the workstation from the branch router suggests that the workstation is on the same network segment as the router. However, the fact that the workstation cannot ping the router indicates that there may be an issue with the subnet mask.

The most likely cause is a missing gateway configuration. But that is not in the list of possibilities. Other causes are not valid and so I chose Subnet mask. But a subnet mask also could cause this issue (even when the gateway is set correct). The machine will do the XOR on the Gateway-IP and configured subnet mask and find that it is on a different network (because subnet mask is wrong not the gateway) and will not be able to find the MAC address of the router to forward the frame. But the router can access the machine because the machine will respond to the ARP request and give the Mac address and the router can send it frames.

A. The router can ping that device except the device cannot ping back..

Incorrect subnet mask mean the workstation is on another subnetwork that is not the switch been ping. Hence every ping made by the workstation is targeting a wrong subnetwork

CHAT GPT SAYS A.

The most likely cause of the incident is an incorrect subnet mask. A subnet mask is used to divide a large network into smaller subnetworks, and it determines which part of the IP address represents the network portion and which part represents the host portion. If the subnet mask is incorrect, it can cause communication issues, such as being unable to access network resources, as described in this scenario.

Incorrect subnet mask

I am not agree with mask. If the ping from router is back, it means that the IP layer is working well. The question is not mention IPs but names, workstation, router... so if the router can ping WORKSTATION, a name, it means that the router can resolve the WORKSTATION name. But the WORKSTATION cannot pint the ROUTER, so if the workstation can replay a ping but not request a pint to ROUTER, it looks like a DNS problem.