A computer cannot connect to the Internet even though IP address and subnet mask are correct. What could be the issue?

A computer cannot connect to the Internet even though IP address and subnet mask are correct. What could be the issue?

• A. Incorrect default gateway IP address
• B. DNS issues
• C. Cable unplugged
• D. Firewall blocking all traffic

Answer: (A)

Routing out of the local subnet relies on the default gateway. Even with a correct IP address and subnet mask, you still need a valid default gateway so traffic destined for networks outside your local LAN can be forwarded to the router and then to the Internet. If the gateway address is incorrect or the gateway itself is unreachable, packets won't have a proper next hop, so Internet access fails despite the host’s own addressing looking fine. DNS issues would affect resolving domain names, but you could still reach hosts by their IP address if the path out is working. A cable unplugged typically shows no link at all rather than just Internet access failing, and a firewall blocking all traffic could cause broader symptoms than just Internet access, though it’s possible. The most likely cause given the scenario is an incorrect default gateway.

Routing out of the local subnet relies on the default gateway. Even with a correct IP address and subnet mask, you still need a valid default gateway so traffic destined for networks outside your local LAN can be forwarded to the router and then to the Internet. If the gateway address is incorrect or the gateway itself is unreachable, packets won't have a proper next hop, so Internet access fails despite the host’s own addressing looking fine.

DNS issues would affect resolving domain names, but you could still reach hosts by their IP address if the path out is working. A cable unplugged typically shows no link at all rather than just Internet access failing, and a firewall blocking all traffic could cause broader symptoms than just Internet access, though it’s possible. The most likely cause given the scenario is an incorrect default gateway.