N10-009 Network Troubleshooting Practice Question
A user reports that they can connect to the internet by IP address but cannot access any websites by domain name. Which command-line tool should a technician use first to isolate the issue?
⚠ Common exam trap
Many candidates choose `ping` first because it is the most familiar troubleshooting tool, but the symptom of working IP connectivity with failed domain resolution specifically points to DNS, making `nslookup` the targeted diagnostic command.
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
✓
nslookup
The user can reach the internet by IP address but not by domain name, which indicates a DNS resolution failure. The `nslookup` command queries DNS servers directly to test name resolution, making it the correct first step to isolate whether the issue is with the DNS server, the client's DNS configuration, or a network path to the DNS server.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ping
Why it's wrong here
While the `ping` utility can accept a hostname as an argument, its primary function is to test basic network connectivity and round-trip time to a target IP address using ICMP Echo Request packets. If a hostname is provided, `ping` relies on the operating system's DNS resolver to translate that name into an IP address *before* sending any packets. Therefore, if DNS resolution is failing, `ping` will report an "unknown host" error, but it does not directly diagnose the DNS server's operational status or the name resolution process itself.
- ✓
nslookup
Why this is correct
The `nslookup` (Name Server Lookup) command-line utility is specifically designed to query Domain Name System (DNS) servers directly. It allows users to test the functionality of DNS by attempting to resolve hostnames to IP addresses, or vice-versa, and can even specify which DNS server to query. This makes `nslookup` the ideal tool for diagnosing issues where a client can successfully reach the internet by IP address but fails to access resources by domain name, pinpointing a problem with name resolution.
- ✗
tracert
Why it's wrong here
The `tracert` (traceroute on Unix-like systems) utility maps the network path a packet takes to reach a destination by sending packets with incrementally increasing Time-To-Live (TTL) values. Its main purpose is to identify the sequence of routers (hops) between a source and a destination, helping to locate where network latency or connectivity issues occur along the path. While `tracert` may resolve hostnames for each intermediate hop, its core function is path discovery, not directly testing or diagnosing DNS server functionality or name resolution failures.
When this WOULD be correct
tracert would be correct if the user reported that they cannot connect to a specific website at all (even by IP) and the technician needs to identify where packets are being dropped along the network path.
- ✗
netstat
Why it's wrong here
The `netstat` (network statistics) command-line tool provides detailed information about active network connections, listening ports, routing tables, and network interface statistics on the local machine. It is used to understand current network activity, identify open services, and troubleshoot local connection issues. However, `netstat` does not interact with DNS servers to perform name resolution queries or diagnose problems related to the translation of domain names into IP addresses; it focuses on the state of network connections and protocols.
When this WOULD be correct
A technician needs to identify which application is listening on a specific port or to check for active TCP connections to troubleshoot a service that is not responding. For example, 'Which command shows all listening ports and their associated processes?'
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.
✓nslookupCorrect answer▾
Why this is correct
The `nslookup` (Name Server Lookup) command-line utility is specifically designed to query Domain Name System (DNS) servers directly. It allows users to test the functionality of DNS by attempting to resolve hostnames to IP addresses, or vice-versa, and can even specify which DNS server to query. This makes `nslookup` the ideal tool for diagnosing issues where a client can successfully reach the internet by IP address but fails to access resources by domain name, pinpointing a problem with name resolution.
✗tracertWrong answer — click to see why▾
Why this is wrong here
The user can connect by IP but not by domain name, indicating a DNS resolution issue. tracert traces the route to a destination but does not test DNS resolution, so it cannot isolate the problem.
★ When this WOULD be the correct answer
tracert would be correct if the user reported that they cannot connect to a specific website at all (even by IP) and the technician needs to identify where packets are being dropped along the network path.
Why candidates choose this
Candidates may think tracert can help identify where connectivity fails, but they overlook that the issue here is DNS, not routing.
✗netstatWrong answer — click to see why▾
Why this is wrong here
netstat displays network connections, routing tables, and interface statistics, but it does not test DNS resolution. Since the user can connect by IP but not by domain name, the issue is likely DNS-related, and netstat cannot diagnose that.
★ When this WOULD be the correct answer
A technician needs to identify which application is listening on a specific port or to check for active TCP connections to troubleshoot a service that is not responding. For example, 'Which command shows all listening ports and their associated processes?'
Why candidates choose this
Candidates may think netstat can show DNS-related issues because it displays network connections, but they overlook that it does not perform or test DNS lookups.
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
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Related to this question
Learn chapter
Troubleshoot: Network Connectivity
Key term
DNS
DNS is the system that translates human-friendly domain names like example.com into machine-readable IP addresses so computers can find each other on a network.
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.
About these practice questions
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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.