N10-009 Network Troubleshooting Practice Question
A user reports that they cannot access a web server by its URL but can access it by IP address. A technician checks the DNS server and finds it is reachable. What is the most likely cause?
⚠ Common exam trap
Watch out — candidates often assume a reachable DNS server means DNS is fully functional, but the question specifically tests the distinction between server reachability and record availability.
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 failure for that specific record
The user can access the web server by IP address but not by URL, which indicates that the name-to-IP resolution is failing. Since the DNS server is reachable, the issue is not with network connectivity to the DNS server but rather with the specific DNS record for that web server. This is a classic DNS resolution failure for that specific record, often due to a missing or incorrect A or AAAA record.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Incorrect default gateway
Why it's wrong here
The default gateway is essential for routing network traffic destined for hosts outside the local subnet. If the user's workstation had an incorrect default gateway configured, it would be unable to send any packets to the web server, assuming the server is not on the same local network segment. The ability to reach the server by its IP address confirms that the workstation's routing, including its default gateway, is correctly configured to allow communication with the remote server.
When this WOULD be correct
A user cannot access any external resources (web, email, etc.) by IP or URL, but internal resources work. The default gateway is misconfigured or unreachable, causing all off-subnet traffic to fail.
- ✓
DNS resolution failure for that specific record
Why this is correct
If a user can successfully access a web server using its IP address but fails when attempting to use its URL (e.g., www.example.com), it strongly indicates a problem with Domain Name System (DNS) resolution. This scenario confirms that network connectivity to the server exists and that the server itself is operational and listening on the correct port. The specific failure to resolve the URL means the DNS server either lacks the necessary A record for that hostname or is unable to provide it to the client, preventing the client from learning the server's IP address from its human-readable name.
- ✗
Firewall blocking port 80
Why it's wrong here
A firewall blocking port 80 (HTTP) would prevent any successful connection attempts to the web server over that port, regardless of whether the client used the server's IP address or its URL. Since the user *can* access the server by its IP address, this demonstrates that port 80 is open and accessible on the server or through any intervening firewalls. Therefore, a firewall blocking port 80 cannot be the cause of the URL-specific access failure, as it would universally block all HTTP traffic.
When this WOULD be correct
A user reports they cannot access a website at all (neither by URL nor IP), and a technician confirms the server is up. In that case, a firewall blocking port 80 could be the cause.
- ✗
IP conflict on the user's workstation
Why it's wrong here
An IP address conflict occurs when two or more devices on the same network are assigned the same IP address, leading to severe and often intermittent network connectivity problems for one or both devices. While an IP conflict would certainly disrupt network access, it would not selectively prevent access by URL while simultaneously allowing access by IP address. Such a conflict would typically manifest as general connectivity loss or highly unreliable communication, affecting all types of network access indiscriminately.
When this WOULD be correct
A user reports they cannot access any network resources, and pinging the default gateway fails. The technician finds another device with the same IP address on the network. In this scenario, IP conflict is the most likely cause.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓DNS resolution failure for that specific recordCorrect answer▾
Why this is correct
If a user can successfully access a web server using its IP address but fails when attempting to use its URL (e.g., www.example.com), it strongly indicates a problem with Domain Name System (DNS) resolution. This scenario confirms that network connectivity to the server exists and that the server itself is operational and listening on the correct port. The specific failure to resolve the URL means the DNS server either lacks the necessary A record for that hostname or is unable to provide it to the client, preventing the client from learning the server's IP address from its human-readable name.
✗Incorrect default gatewayWrong answer — click to see why▾
Why this is wrong here
An incorrect default gateway would prevent access to any external IP address, but the user can access the web server by IP, indicating routing is functional. The issue is specific to URL access, pointing to DNS, not gateway.
★ When this WOULD be the correct answer
A user cannot access any external resources (web, email, etc.) by IP or URL, but internal resources work. The default gateway is misconfigured or unreachable, causing all off-subnet traffic to fail.
Why candidates choose this
Candidates may confuse symptoms of a DNS failure with a gateway issue, as both can cause 'cannot access website' errors, but the ability to reach by IP rules out gateway problems.
✗Firewall blocking port 80Wrong answer — click to see why▾
Why this is wrong here
The user can access the web server by IP address, which indicates that port 80 is not blocked. A firewall blocking port 80 would prevent access by both URL and IP.
★ When this WOULD be the correct answer
A user reports they cannot access a website at all (neither by URL nor IP), and a technician confirms the server is up. In that case, a firewall blocking port 80 could be the cause.
Why candidates choose this
Candidates often associate web access issues with firewall rules, especially when the problem involves a web server, without considering that IP access works fine.
✗IP conflict on the user's workstationWrong answer — click to see why▾
Why this is wrong here
An IP conflict would cause intermittent connectivity or complete loss of network access, not a specific inability to resolve a URL while IP access works. The user can reach the server by IP, ruling out IP conflict.
★ When this WOULD be the correct answer
A user reports they cannot access any network resources, and pinging the default gateway fails. The technician finds another device with the same IP address on the network. In this scenario, IP conflict is the most likely cause.
Why candidates choose this
Candidates may confuse symptoms of IP conflict (e.g., network drops) with DNS issues, or they may think IP conflict can selectively block name resolution.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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 |
Go deeper
Related to this question
Learn chapter
Troubleshoot: Network Connectivity
Key term
URL
A URL is a string of characters that identifies the location and method to access a resource on the internet.
Key term
Name Server
A name server is a specialized server that translates human-readable domain names into machine-readable IP addresses so that computers can find each other on a network.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 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 N10-009 exam.