XK0-006 Troubleshooting Practice Question
An administrator is investigating a network issue where a server cannot connect to an external website. They run `ping 8.8.8.8` successfully, but `ping google.com` fails. Which TWO of the following are the most likely causes? (Choose TWO.)
⚠ Common exam trap
XK0-006 often tests the diagnostic reasoning that successful IP ping plus failed hostname ping isolates the fault to name resolution, tempting candidates to blame routing or firewalls that would have broken both pings.
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 DNS server is unreachable or misconfigured.
Option C is correct because the successful `ping 8.8.8.8` proves IP connectivity and routing to the internet work, while the failure of `ping google.com` indicates name resolution is failing — meaning the configured DNS server is unreachable, misconfigured, or not responding on port 53. Option E is correct because an incorrect entry for google.com in /etc/hosts would cause the resolver to return a wrong IP address for that hostname before ever querying DNS, producing exactly this symptom (numeric IP works, hostname fails). Option A is wrong because a down network interface would prevent even `ping 8.8.8.8` from succeeding. Option B is wrong because a misconfigured default gateway would break routing to external IP addresses, so the numeric ping to 8.8.8.8 would also fail. Option D is wrong because a firewall blocking ICMP would cause both pings to fail, not just the hostname-based one.
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 network interface is down.
Why it's wrong here
A down interface would prevent the successful ping to 8.8.8.8, since that reply proves Layer 3 connectivity is already working. Administrators check interface state first when nothing responds at all, but here only name resolution fails, pointing to DNS or resolver configuration instead.
- ✗
The default gateway is misconfigured.
Why it's wrong here
A misconfigured default gateway would stop the ping to 8.8.8.8 from succeeding, because that address sits outside the local subnet. Gateway faults are the classic cause of total external unreachability, yet here numeric connectivity works, so the failure lies in name resolution.
- ✓
The DNS server is unreachable or misconfigured.
Why this is correct
Successful pinging of 8.8.8.8 proves IP connectivity and routing work, isolating the fault to name resolution. An unreachable or misconfigured DNS server prevents resolving google.com to an IP address, exactly matching the symptom of numeric pings succeeding while hostname pings fail.
- ✗
The firewall is blocking ICMP traffic.
Why it's wrong here
Blocking ICMP would also block the successful ping to 8.8.8.8, so the firewall is clearly permitting that traffic. Firewall ICMP rules are investigated when all pings fail, but this scenario shows numeric pings succeeding while only hostname lookups fail, implicating DNS.
- ✓
The /etc/hosts file has an incorrect entry for google.com.
Why this is correct
Pinging 8.8.8.8 succeeds, confirming routing and connectivity are fine, so the failure lies in name resolution. An incorrect /etc/hosts entry for google.com overrides DNS and maps the hostname to a wrong or unreachable address, producing the observed failure.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This XK0-006 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the XK0-006 exam.