CompTIA A+ Core 1 (220-1201)NetworkingEasy
A home user's laptop can reach devices on the local network but cannot access any websites on the internet. The IP configuration shows a valid IP address, subnet mask, and DNS server, but the 'Default Gateway' field is blank. What is the MOST likely reason the user cannot browse the internet?
- AThe device cannot route traffic outside the local subnet without a gateway
- BThe subnet mask is too large
- CThe wireless adapter is disabled
- DThe DNS server address is incorrect
Show answer & explanationAnswer & explanation
Correct answer: A. The device cannot route traffic outside the local subnet without a gateway
The default gateway is the router address a device uses to send traffic destined for networks outside its own subnet, such as the internet. Without it, local communication works but internet-bound packets have nowhere to go.
Why the other options are wrong
- B. An oversized subnet mask would cause local addressing issues, not this specific symptom.
- C. If the adapter were disabled, local network access would also fail.
- D. DNS failure would cause name resolution errors, not total inability to leave the subnet.
Default Gateway
The router IP address a host uses to send traffic to destinations outside its own subnet.
- Required for any communication beyond the local network
- Usually the router's LAN interface IP
- Missing gateway = local access works, internet access fails
Memory trick: No gateway, no gate out of town.