220-1102 Question 173
Single answerClient network configurationA technician is configuring a Windows 11 laptop for a small office. The office router provides DHCP addresses in the 192.168.10.0/24 network and also hosts the internet connection. The user reports that after the technician manually configured the laptop's IP settings, the laptop can reach a local file server at 192.168.10.50 but cannot browse websites by name. The technician runs ipconfig and sees the following: IP address 192.168.10.25, subnet mask 255.255.255.0, default gateway 192.168.10.1, DNS server 127.0.0.1. Which configuration change will most likely resolve the problem?
- A
Change the DNS server setting from 127.0.0.1 to the router's DNS server or another valid DNS server address
- B
Change the subnet mask to 255.255.0.0 so the laptop can reach internet hosts
- C
Remove the default gateway because local network access is already working
- D
Change the IP address to 169.254.10.25 to allow automatic local connectivity
Show answer and explanation
Correct answer: A
Explanation
This scenario tests practical client network configuration troubleshooting. Because the laptop can reach a local server by IP, the IP address, subnet mask, and local Layer 3 communication are functioning. Because websites cannot be reached by name, the most likely issue is DNS misconfiguration. In Windows and standard TCP/IP networking, 127.0.0.1 is the loopback address and refers to the local machine. Unless the client is intentionally configured to run a local DNS resolver, using 127.0.0.1 as the DNS server will prevent normal name resolution. Best practice is to configure clients with a valid DNS server, often provided automatically through DHCP or set manually to an internal DNS server, router DNS forwarder, or approved public DNS service. This aligns with standard Microsoft TCP/IP configuration guidance and common enterprise network troubleshooting methodology: verify IP settings, confirm gateway functionality, and check DNS when name-based access fails but IP-based access succeeds.
- A. Correct.
Correct. The laptop can reach a local host by IP address, which shows basic local connectivity is working. It cannot browse websites by name, which strongly indicates a DNS resolution problem. Setting DNS to 127.0.0.1 points the laptop to itself for DNS queries, but unless the laptop is actually running a DNS service, name resolution will fail. Configuring a valid DNS server, such as the router if it provides DNS forwarding or a known internal/external DNS server, is the appropriate fix.
- B. Incorrect.
Incorrect. A subnet mask of 255.255.255.0 is appropriate for a 192.168.10.0/24 network. Changing it to 255.255.0.0 would expand the local subnet incorrectly and would not fix DNS name resolution. This distractor reflects the misconception that internet access issues are commonly caused by the subnet mask when the real issue is name resolution.
- C. Incorrect.
Incorrect. The default gateway is required for traffic destined outside the local subnet, including internet access. Removing it would make internet connectivity worse, not better. The fact that local access works does not mean the gateway is unnecessary; it only means same-subnet communication is functioning.
- D. Incorrect.
Incorrect. An address in the 169.254.0.0/16 range is an APIPA address used when DHCP fails and no manual address is assigned. Assigning a 169.254.x.x address would place the laptop outside the office's intended 192.168.10.0/24 network and would not provide normal routed connectivity or DNS resolution. This is a common misconception about automatic addressing.