82. A network administrator is troubleshooting a connectivity issue between two devices on two different subnets. The administrator verifies that both devices can successfully ping other devices on the same subnet. Which of the following is the most likely cause of the connectivity issue?
Answer: A
Incorrect default gateway
An incorrect default gateway is the most likely cause of the connectivity issue between the two devices on different subnets, as it prevents packets from being routed correctly between subnets.
A) Incorrect default gateway
This option is correct because if the default gateway is not set correctly on either device, they will be unable to communicate with devices on a different subnet. The default gateway serves as the access point for traffic destined for networks outside the local subnet, so if it is misconfigured, connectivity will be lost.
B) Faulty Ethernet cable
While a faulty Ethernet cable can cause connectivity issues, it would typically prevent devices from communicating even within the same subnet. Since both devices can ping others on their respective subnets, this indicates that the cabling is functional.
C) Wrong duplex settings
Wrong duplex settings might lead to performance degradation or collisions but would not typically cause a complete inability to communicate across subnets. Since the question specifies that both devices can ping others on their subnets, this option is not the cause of the issue.
D) VLAN mismatch
A VLAN mismatch could also cause connectivity issues, but it would generally be indicated by the devices being unable to communicate even within the same VLAN. Given that both devices are able to ping others within their subnets, this suggests that VLAN configurations are likely correct.
Conclusion
The most plausible explanation for the connectivity issue is an incorrect default gateway, as it directly impacts the ability of devices to communicate across different subnets. Options B, C, and D do not adequately account for the successful communication observed within the subnets, making them less likely causes of the issue.