- A
DNS resolution problem
Domain name cannot be resolved to IP.
- B
Web server is down
Why wrong: Would block both.
- C
Firewall blocking port 80
Why wrong: Would block both IP and domain access.
- D
Incorrect default gateway
Why wrong: Would affect all connectivity.
Question 425 of 1,000
XK0-005 Troubleshooting Practice Question
This XK0-005 practice question tests your understanding of troubleshooting. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that they cannot access a website by domain name but can access it by IP address. Which of the following is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
DNS resolution problem
The user can access the website by IP address but not by domain name, which directly indicates that the system is unable to resolve the domain name to its corresponding IP address. This is a classic symptom of a DNS resolution problem, where the DNS client cannot query a DNS server or the DNS server fails to return the correct A or AAAA record. The fact that the web server is reachable by IP confirms that network connectivity and the web service itself are functioning correctly.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DNS resolution problem
Why this is correct
Domain name cannot be resolved to IP.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Web server is down
Why it's wrong here
Would block both.
- ✗
Firewall blocking port 80
Why it's wrong here
Would block both IP and domain access.
- ✗
Incorrect default gateway
Why it's wrong here
Would affect all connectivity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between connectivity issues and name resolution issues, and the trap here is that candidates may confuse a DNS failure with a web server or firewall problem, even though the ability to reach the server by IP clearly rules out those causes.
Detailed technical explanation
How to think about this question
DNS resolution involves querying a recursive resolver (e.g., 8.8.8.8) for an A or AAAA record, which is then cached locally by the stub resolver (e.g., systemd-resolved or nscd). If the /etc/resolv.conf file contains an invalid or unreachable nameserver, or if the DNS server itself is misconfigured (e.g., missing zone delegation), the lookup will fail while direct IP connectivity remains intact. Tools like `dig`, `nslookup`, or `host` can be used to isolate whether the failure is at the resolver or authoritative server level.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Visual reference
Quick reference
Common DNS Record Types
| Record | Purpose | Example |
|---|---|---|
| A | IPv4 address mapping | example.com → 93.184.216.34 |
| AAAA | IPv6 address mapping | example.com → 2606:2800::1 |
| CNAME | Alias to another hostname | www → example.com |
| MX | Mail server for domain | example.com → mail.example.com (priority 10) |
| TXT | Text data (SPF, DKIM, verification) | v=spf1 include:_spf.example.com ~all |
| NS | Authoritative name servers | example.com NS ns1.example.com |
| PTR | Reverse DNS (IP → hostname) | 34.216.184.93.in-addr.arpa → example.com |
| SOA | Zone authority record | Primary NS, admin email, serial, TTL defaults |
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Troubleshooting — study guide chapter
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: DNS resolution problem — The user can access the website by IP address but not by domain name, which directly indicates that the system is unable to resolve the domain name to its corresponding IP address. This is a classic symptom of a DNS resolution problem, where the DNS client cannot query a DNS server or the DNS server fails to return the correct A or AAAA record. The fact that the web server is reachable by IP confirms that network connectivity and the web service itself are functioning correctly.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
This XK0-005 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 XK0-005 exam.
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