Why a New PC Can't Access the Internet: Step‑by‑Step DNS Troubleshooting

A client bought a new computer, connected it to the corporate network, and found that it could not access the internet while other PCs worked fine. The cable’s link light was on, and the computer obtained an IP address automatically, but the network icon showed no internet connectivity.

Running ping to a public IP succeeded, confirming that the network path was functional and indicating a DNS resolution problem. The computer’s DNS server was set to 47.100.36.1, an Alibaba Cloud IP that was not a public DNS service.

Changing the DNS to Alibaba’s public DNS (223.5.5.5 or 223.6.6.6) restored internet access, confirming the DNS issue. Further inspection revealed that other workstations were using the public DNS address 1.1.1.1, provided by Cloudflare and APNIC.

The DHCP settings on the router were edited to assign 1.1.1.1 as the DNS server. After the change, the network icon switched to the internet‑available symbol, and the computer could ping Baidu successfully.

Performance testing showed that using 1.1.1.1 in China resulted in high DNS latency (500‑600 ms), whereas Google’s DNS 8.8.8.8 responded in 40‑60 ms and domestic public DNS responded in 4‑6 ms. The results demonstrate that foreign DNS servers are not inherently faster; latency depends on the network environment.