Cisco Certified Support Technician (CCST) NetworkingNetwork AccessMedium
A network technician is troubleshooting a network issue where a user's computer can ping other devices on the local subnet but cannot reach resources on a remote network. The switch port connecting the user's computer is configured as an access port in VLAN 10. The router interface connected to the switch is configured with a subinterface for VLAN 10, using the IP address 192.168.10.1/24. The user's computer has an IP address of 192.168.10.50/24. What is the most likely missing configuration element on the user's computer?
- AIncorrect IP address
- BMissing or incorrect subnet mask
- CMissing or incorrect default gateway
- DMissing or incorrect DNS server
Show answer & explanationAnswer & explanation
Correct answer: C. Missing or incorrect default gateway
The ability to ping devices on the local subnet (192.168.10.x) indicates the IP address and subnet mask are likely correct. However, the inability to reach remote networks points to a missing or incorrect default gateway, as the default gateway is essential for routing traffic outside the local subnet.
Why the other options are wrong
- A. If the IP address was incorrect, the user might not be able to ping local devices correctly.
- B. An incorrect subnet mask could prevent communication even within the local subnet, which is not the case here.
- D. A missing DNS server would prevent name resolution (e.g., accessing websites by name) but would not stop communication by IP address to remote networks.
Default Gateway
A router or Layer 3 switch interface on a local network that acts as a forwarding point for all traffic destined for other networks.
- Crucial for inter-subnet communication.
- Must be an IP address within the local subnet.
- Network devices need it to reach destinations outside their local segment.
Memory trick: Gateway is the exit door to the world.