Flush DNS Cache: First Step When Only One Workstation Can't Resolve Names
A user reports that they can access internal network resources and the internet by IP address, but cannot browse websites using domain names. Other users on the same network can browse the internet normally. Which of the following should the technician do FIRST?
Quick Answer
The correct first step is to flush the DNS cache on the user’s computer. This is the right move because the user can access resources by IP address but not by domain name, which points directly to a DNS resolution failure. Since other users on the same network can browse the internet normally, the problem is isolated to that single workstation, making a corrupted or stale DNS cache the most likely culprit. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your ability to differentiate between network-wide issues and workstation-specific problems; a common trap is to immediately check the router or DHCP settings when the real issue is local name resolution. Remember that when only one workstation can’t resolve names, flushing the DNS cache with ipconfig /flushdns is the quickest and most logical first step. Memory tip: “One workstation, one flush—if others browse fine, clear the DNS line.”
⚠ Common exam trap
Test-takers frequently assume a DNS server or DHCP issue is at fault because the symptom involves domain names, but the fact that other users are unaffected points to a local client-side cache problem, not a server-side or infrastructure failure.
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
✓
Flush the DNS cache on the user's computer
The user can access resources by IP address but not by domain name, which indicates a DNS resolution failure. Since other users on the same network can browse normally, the issue is isolated to this specific workstation. Flushing the DNS cache (ipconfig /flushdns) clears any corrupted or stale DNS entries that may be preventing successful name resolution, making it the quickest and most logical first step.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Check the DHCP server configuration
Why it's wrong here
Other users on the same subnet resolve names correctly, so the DHCP scope's DNS settings are evidently valid; the fault lies with this client's configuration or cache. It is tempting because DHCP supplies DNS servers, but a server-wide misconfiguration would affect everyone.
When this WOULD be correct
If multiple users on the same network cannot browse websites using domain names but can access resources by IP address, the DHCP server configuration (e.g., incorrect DNS server assignment) would be the likely cause and should be checked first.
- ✓
Flush the DNS cache on the user's computer
Why this is correct
Name resolution failure isolated to one machine, while IP connectivity works, points to a corrupted local DNS cache. Flushing it clears stale or poisoned entries, restoring domain-name browsing without affecting other users who resolve names normally.
- ✗
Restart the DNS service on the domain controller
Why it's wrong here
Restarting the domain controller's DNS service affects every client, yet other users resolve names normally, so the fault is local to this workstation. It is tempting because DNS is implicated, but server-side action is warranted only when resolution fails network-wide.
When this WOULD be correct
This would be correct if multiple users or the entire network cannot resolve domain names, indicating a server-side DNS issue. The technician should then restart or troubleshoot the DNS service on the domain controller.
- ✗
Replace the network cable
Why it's wrong here
The cable already carries IP traffic successfully, so physical connectivity is proven working; replacing it cannot restore name resolution. It is tempting as a quick hardware fix, but cabling faults would also break IP addressing, which the user retains.
When this WOULD be correct
A user reports no network connectivity at all (cannot ping any IP or access resources). The technician checks the cable and finds it damaged, so replacing it restores connectivity.
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.
✓Flush the DNS cache on the user's computerCorrect answer▾
Why this is correct
Name resolution failure isolated to one machine, while IP connectivity works, points to a corrupted local DNS cache. Flushing it clears stale or poisoned entries, restoring domain-name browsing without affecting other users who resolve names normally.
✗Check the DHCP server configurationWrong answer — click to see why▾
Why this is wrong here
The issue is isolated to a single user, not the entire network, so checking the DHCP server configuration is unnecessary. Other users can browse normally, indicating the DHCP server is working correctly.
★ When this WOULD be the correct answer
If multiple users on the same network cannot browse websites using domain names but can access resources by IP address, the DHCP server configuration (e.g., incorrect DNS server assignment) would be the likely cause and should be checked first.
Why candidates choose this
Candidates may think DNS issues are always server-side, overlooking that a local DNS cache corruption can cause the same symptoms for a single user.
✗Restart the DNS service on the domain controllerWrong answer — click to see why▾
Why this is wrong here
The issue is isolated to a single user, not the entire network. Restarting the DNS service on the domain controller would affect all users and is not the first step for a client-specific problem.
★ When this WOULD be the correct answer
This would be correct if multiple users or the entire network cannot resolve domain names, indicating a server-side DNS issue. The technician should then restart or troubleshoot the DNS service on the domain controller.
Why candidates choose this
Candidates may assume DNS problems always originate from the server, overlooking client-side causes like a corrupted local DNS cache.
✗Replace the network cableWrong answer — click to see why▾
Why this is wrong here
The user can access internal resources and the internet by IP address, indicating the network cable is functioning. The issue is DNS resolution, not physical connectivity.
★ When this WOULD be the correct answer
A user reports no network connectivity at all (cannot ping any IP or access resources). The technician checks the cable and finds it damaged, so replacing it restores connectivity.
Why candidates choose this
Candidates may default to physical layer troubleshooting when a user has connectivity issues, overlooking that the symptom (domain name failure) points to a higher-layer problem.
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
1 more way 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 their workstation can access internal network resources by IP address (e.g., \\192.168.1.100\share) and can browse the internet using IP addresses (e.g., http://8.8.8.8), but cannot access any resources by hostname (e.g., \\fileserver\share or www.example.com). Other workstations on the same subnet can resolve hostnames without issue. The workstation obtains its IP address via DHCP. The technician runs ipconfig and sees: IP: 192.168.1.105, Subnet Mask: 255.255.255.0, Default Gateway: 192.168.1.1, DNS Server: 192.168.1.1. Which of the following is the MOST likely cause of this issue?
medium- ✓ A.The DNS resolver cache on the workstation is corrupted or contains invalid entries.
- B.The DHCP scope is exhausted, and the workstation received an incorrect DNS server address.
- C.NetBIOS over TCP/IP is disabled on the workstation, preventing NetBIOS name resolution.
- D.The workstation is in the wrong workgroup or domain, so it cannot resolve remote hostnames.
Why A: The workstation can reach resources by IP address but not by hostname, indicating a name resolution problem. Since other workstations on the same subnet resolve hostnames correctly, the DNS server (192.168.1.1) is functioning properly. The issue is isolated to this workstation, making a corrupted DNS resolver cache the most likely cause. Clearing the cache with `ipconfig /flushdns` would force fresh queries and resolve the issue. Option B is incorrect because the DNS server address shown is correct (192.168.1.1) and DHCP exhaustion would produce an APIPA address, not a valid one. Option C is incorrect because NetBIOS over TCP/IP is used for NetBIOS name resolution, not DNS-based hostname resolution used for accessing websites and UNC paths by hostname. Option D is incorrect because workgroup or domain membership does not affect general hostname resolution via DNS; it affects browsing network resources in Active Directory but not basic name resolution.
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.