DNS Server Problem: Why You Can Browse by IP but Not Domain Name
A user in a small office can access shared files on the local network and can connect to the internet using a web browser when entering IP addresses directly (e.g., http://198.51.100.1) but cannot access any websites by their domain names (e.g., www.example.com). The network uses a DHCP server. Which of the following is the most likely cause of this issue?
Quick Answer
The answer is an incorrect or unreachable DNS server address. This is correct because the ability to access the internet by IP but not domain name points directly to a failure in name resolution; DNS is the service that translates human-readable domain names into IP addresses, so when it is misconfigured or unreachable, the browser can still connect to raw IPs but cannot resolve names like www.example.com. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your understanding of how DHCP distributes network settings, including the DNS server, and a common trap is to suspect the gateway or firewall when the real issue is simply a bad DNS entry. Remember the memory tip: “IP works, names don’t? DNS is what you want.”
⚠ Common exam trap
Candidates often confuse DNS failure with a default gateway issue, but the ability to reach external IP addresses proves that routing is working, isolating the problem to name resolution.
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 address is incorrect or unreachable.
The user can access resources by IP address but not by domain name, which indicates that name resolution is failing. Since the network uses DHCP, the most likely cause is that the DHCP server is providing an incorrect or unreachable DNS server address, preventing the client from resolving domain names to IP addresses.
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 configured incorrectly.
Why it's wrong here
The gateway is demonstrably functional: the browser reaches internet hosts by raw IP, which requires a working default route. A misconfigured gateway would block all off-subnet traffic, not just name resolution. The gateway is tempting because it is the classic DHCP fault, but it would be the answer if no external IP address were reachable.
When this WOULD be correct
In a scenario where a user cannot access any external resources (including by IP address) but can access local resources, an incorrect default gateway would be the likely cause.
- ✓
The DNS server address is incorrect or unreachable.
Why this is correct
Successful access by IP address proves routing and connectivity work, while domain-name failures isolate the fault to name resolution. An incorrect or unreachable DNS server address delivered by DHCP prevents the client from resolving www.example.com, matching the stem's symptoms exactly.
- ✗
The subnet mask is set to a value that prevents Internet access.
Why it's wrong here
Name resolution fails while IP routing to the internet still works, so the mask is not the fault; a wrong mask would break local subnet reachability or the gateway path, not DNS lookups alone. A mask is tempting because it defines which addresses are local, but the DHCP scope here already delivers working local and routed connectivity.
When this WOULD be correct
A user cannot access any network resources, including the internet or local devices, but can ping the loopback address. The subnet mask is incorrectly set to 255.255.255.255, preventing communication with any other device.
- ✗
The DHCP server has exhausted its address pool.
Why it's wrong here
Pool exhaustion prevents clients obtaining any lease, so the user would lack an IP address and reach neither shared files nor IP-addressed websites. It is tempting because DHCP faults commonly cause connectivity loss, but here name resolution alone is failing while IP routing works.
When this WOULD be correct
A user cannot obtain an IP address via DHCP and receives a 169.254.x.x APIPA address, preventing any network access. The DHCP server has no available addresses to assign.
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 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓The DNS server address is incorrect or unreachable.Correct answer▾
Why this is correct
Successful access by IP address proves routing and connectivity work, while domain-name failures isolate the fault to name resolution. An incorrect or unreachable DNS server address delivered by DHCP prevents the client from resolving www.example.com, matching the stem's symptoms exactly.
✗The default gateway is configured incorrectly.Wrong answer — click to see why▾
Why this is wrong here
The user can access the internet via IP address, indicating the default gateway is correctly routing traffic. The issue is with domain name resolution, not gateway configuration.
★ When this WOULD be the correct answer
In a scenario where a user cannot access any external resources (including by IP address) but can access local resources, an incorrect default gateway would be the likely cause.
Why candidates choose this
Candidates often associate internet connectivity issues with the default gateway, overlooking that IP-based access works, which isolates the problem to DNS.
✗The subnet mask is set to a value that prevents Internet access.Wrong answer — click to see why▾
Why this is wrong here
The subnet mask determines which part of an IP address is the network portion and which is the host portion. If it were set incorrectly, the user might not be able to communicate with devices on different subnets, but since the user can access the internet via IP address and local shared files, the subnet mask is likely correct.
★ When this WOULD be the correct answer
A user cannot access any network resources, including the internet or local devices, but can ping the loopback address. The subnet mask is incorrectly set to 255.255.255.255, preventing communication with any other device.
Why candidates choose this
Candidates may confuse subnet mask issues with DNS issues, thinking that an incorrect subnet mask could block domain name resolution, but DNS is a separate service that translates names to IP addresses.
✗The DHCP server has exhausted its address pool.Wrong answer — click to see why▾
Why this is wrong here
The user can access the internet via IP addresses, indicating that the default gateway and DHCP address pool are functional. An exhausted DHCP pool would prevent obtaining an IP address, not cause DNS resolution failure.
★ When this WOULD be the correct answer
A user cannot obtain an IP address via DHCP and receives a 169.254.x.x APIPA address, preventing any network access. The DHCP server has no available addresses to assign.
Why candidates choose this
Candidates may confuse DHCP exhaustion with DNS issues, thinking that running out of IP addresses could cause intermittent connectivity or name resolution failures, but the symptoms here clearly point to DNS.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Same concept, more angles
2 more ways this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user reports that they can access internal network resources by IP address but cannot browse the internet by domain name (e.g., www.google.com). The technician checks the workstation's network adapter settings and sees that the IP address is obtained via DHCP. Which of the following is the MOST likely cause of this issue?
easy- A.Incorrect subnet mask
- B.Wrong default gateway
- ✓ C.DNS server configuration
- D.Duplicate IP address
Why C: The user can access internal resources by IP address but not by domain name, which indicates that name resolution is failing. Since the workstation obtains its IP address via DHCP, the DNS server configuration is likely missing or incorrect, preventing the system from translating domain names like www.google.com into IP addresses.
Variation 2. A technician is troubleshooting a workstation that can access internal network resources and the internet, but users report that they cannot browse websites using domain names (e.g., www.example.com). The technician opens a command prompt and successfully pings a public IP address (8.8.8.8), but pinging www.google.com returns 'Ping request could not find host'. The workstation receives IP settings via DHCP. Which of the following is the MOST likely cause?
medium- A.The default gateway is misconfigured
- ✓ B.The DNS server addresses are not being provided by DHCP
- C.The workstation's firewall is blocking DNS traffic
- D.The router's NAT is misconfigured
Why B: The workstation can ping a public IP address (8.8.8.8) but cannot resolve domain names like www.google.com. This indicates that IP connectivity is working, but DNS resolution is failing. Since the workstation receives IP settings via DHCP, the most likely cause is that the DHCP server is not providing correct DNS server addresses, leaving the workstation without a valid DNS resolver.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 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 220-1101 exam.