A desktop can connect to a file server but cannot access the internet.

CompTIA A+ teaches that the default gateway is required for any device to communicate with external networks such as the internet. Without a configured default gateway, the computer can communicate only with devices on the same local subnet explaining why the file server is reachable.

DNS and IPv6 settings are not the issue; without a gateway, external routing cannot occur. Flushing DNS affects hostname resolution, not routing. NetBIOS settings have no effect on internet connectivity.

Adding or correcting the default gateway (usually the router’s LAN IP, such as 192.168.1.1) will allow the PC to route traffic beyond its local network.

This aligns precisely with CompTIA’s troubleshooting steps for missing or incorrect gateway configuration.