220-1101 Question 62
Single answer53 – Domain Name System (DNS)A technician is troubleshooting a Windows laptop that can reach internet sites by IP address, but users cannot browse to sites by name. For example, the user can open http://142.250.190.78, but browsing to www.google.com fails. Other devices on the same network can access websites normally by name. Which of the following is the MOST likely cause of this issue?
- A
The laptop has an incorrect DNS server address configured
- B
The default gateway on the laptop is offline
- C
The ISP is blocking outbound HTTPS traffic
- D
The laptop has a duplicate IP address on the network
Show answer and explanation
Correct answer: A
Explanation
This scenario tests practical DNS troubleshooting. DNS translates human-readable domain names such as www.google.com into IP addresses. When a system can communicate with external resources by IP address but not by name, technicians should suspect DNS first. In a real support situation, common next steps would include checking the DNS server settings with ipconfig /all, testing name resolution with nslookup, and renewing DHCP information if the DNS settings were obtained automatically. This aligns with standard TCP/IP troubleshooting practices documented by Microsoft and other networking best-practice references: confirm connectivity, isolate whether the problem is routing or name resolution, and then verify local adapter configuration.
- A. Correct.
This is correct. If the laptop can reach websites by IP address but not by hostname, basic IP connectivity is working, but name resolution is failing. A common cause is that the device is using an invalid or unreachable DNS server. Since other devices on the same network resolve names successfully, the issue is likely specific to this laptop's DNS configuration rather than a network-wide outage.
- B. Incorrect.
This is incorrect. If the default gateway were offline or misconfigured, the laptop would typically be unable to reach external IP addresses as well as hostnames. The fact that the user can browse directly to a public IP shows that routing to the internet is functioning.
- C. Incorrect.
This is incorrect. If outbound HTTPS traffic were blocked, users would have trouble reaching secure websites regardless of whether they used a hostname or an IP address. The scenario specifically points to a name resolution problem because access by IP works while access by name does not.
- D. Incorrect.
This is incorrect. A duplicate IP address can cause intermittent or total connectivity problems, but it does not specifically explain why only hostname resolution fails while direct access by IP still works consistently. The symptom pattern is much more closely aligned with a DNS issue.