easyMultiple ChoiceObjective-mapped
XK0-006 Practice Question: Troubleshoot a network connectivity issue on a…
A technician needs to troubleshoot a network connectivity issue on a Linux server. The server can ping its own IP address but cannot ping the default gateway. Which of the following is the most likely cause?
⚠ Common exam trap
It's easy for candidates to assume a routing or firewall issue (options A or C) because they focus on Layer 3, but the ability to ping the local IP proves the stack is healthy, pointing instead to a physical or data-link layer problem that prevents any off-subnet communication.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Ethernet cable is disconnected or the switch port is down.
The server can ping its own IP address (loopback or local interface), confirming that the network stack is functioning and the interface is up. However, the inability to ping the default gateway indicates a Layer 1 or Layer 2 issue, such as a disconnected Ethernet cable or a switch port that is administratively down, which prevents any traffic from leaving the local subnet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The default gateway is misconfigured in the routing table.
Why it's wrong here
A misconfigured gateway would cause 'Network is unreachable', not a timeout.
- ✗
The DNS resolver is not configured correctly.
Why it's wrong here
DNS is not needed for pinging an IP address.
- ✗
The iptables firewall is blocking outgoing ICMP traffic.
Why it's wrong here
A firewall would also block local pings if configured to block ICMP.
- ✓
The Ethernet cable is disconnected or the switch port is down.
Why this is correct
Local ping works (loopback or local IP) but external fails, indicating a layer 1/2 issue.
Visual reference
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Related to this question
Learn chapter
Linux Fundamentals and History
Key term
Linux
Linux is an open-source operating system that manages computer hardware and software, widely used in servers, desktops, and embedded systems.
Key term
Subnet
A subnet is a logical subdivision of an IP network, created by partitioning a larger network address space using subnet masks.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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