Cisco CCNA (200-301)Network FundamentalsHard
A network engineer is troubleshooting a client workstation that cannot access resources on a different subnet but can communicate with other devices on its local subnet. The `ipconfig` output shows an IP address, subnet mask, and a default gateway address. What is the MOST likely cause of the issue?
- AIncorrect IP address on the workstation.
- BDuplicate IP address detected on the local subnet.
- CThe default gateway is configured incorrectly or is unreachable.
- DDHCP server is down.
Show answer & explanationAnswer & explanation
Correct answer: C. The default gateway is configured incorrectly or is unreachable.
If a host can communicate within its local subnet but not with devices on other subnets, it indicates that local connectivity is working, but the host cannot forward traffic outside its local network. This is the primary function of the default gateway, so an issue with its configuration or reachability is the most likely cause.
Why the other options are wrong
- A. If the IP address was incorrect, the workstation likely wouldn't be able to communicate even on its local subnet.
- B. A duplicate IP address would cause intermittent connectivity problems, potentially even on the local subnet, and an `ipconfig` output would often show an APIPA address or a warning.
- D. The `ipconfig` output shows an IP address, meaning the client successfully obtained an address, so the DHCP server being down is not the immediate cause.
Default Gateway Function
The default gateway is the IP address of the router interface on the local subnet that a host uses to forward traffic destined for hosts on other networks.
- Essential for inter-subnet communication.
- Must be an IP address within the host's local subnet.
- If incorrect or unreachable, the host is isolated from other networks.
Memory trick: If you can't leave your street, your gate or bridge is broken.