220-1101 Question 125
Single answerRoutersA small office replaces its ISP-provided router with a new wireless router. After the installation, employees can connect to the router's Wi-Fi and reach shared files on the local network, but no one can browse the internet. The ISP modem is working, and its Ethernet cable is connected to one of the new router's numbered LAN ports. Which action should the technician take FIRST to restore internet access for the office?
- A
Move the modem's Ethernet cable from the router's LAN port to the router's WAN/Internet port
- B
Disable DHCP on the new router so client PCs can obtain public IP addresses directly from the ISP
- C
Change the router's SSID to match the office's previous wireless network name
- D
Configure port forwarding for HTTP and HTTPS traffic on the router
Show answer and explanation
Correct answer: A
Explanation
This scenario tests practical knowledge of basic router installation and SOHO network topology. In a standard setup, the ISP modem or handoff device connects to the router's WAN/Internet port, and internal devices connect to the router's LAN ports or Wi-Fi. The router then routes traffic between the private internal network and the ISP connection, typically using NAT and DHCP. Connecting the modem to a LAN port bypasses the intended upstream interface and commonly results in a network where local communication works but internet access does not. This aligns with standard router deployment guidance from common SOHO router documentation and networking best practices: verify physical connections first, especially WAN versus LAN placement, before changing higher-level settings such as DHCP, SSID, or port forwarding.
- A. Correct.
Correct. On a typical SOHO router, the ISP modem must connect to the dedicated WAN/Internet port, not a LAN switch port. The router uses the WAN interface to obtain upstream connectivity from the ISP and then performs routing, NAT, and usually DHCP for internal clients. If the modem is plugged into a LAN port instead, local devices may still communicate with each other on the internal network, but internet traffic will not be routed properly.
- B. Incorrect.
Incorrect. Disabling DHCP would not fix the upstream connectivity issue and would likely create additional addressing problems for client devices. In a standard small-office setup, the router should provide private IP addresses to internal devices, while the router itself communicates with the ISP on the WAN side. Client PCs generally should not receive public IP addresses directly from the ISP through the internal LAN.
- C. Incorrect.
Incorrect. The SSID affects how users identify and join the wireless network, but it does not determine whether the router has a functional internet uplink. Matching the previous SSID might help with client convenience or roaming, but it would not resolve the lack of internet access caused by an incorrect physical connection.
- D. Incorrect.
Incorrect. Port forwarding is used to allow unsolicited inbound traffic from the internet to reach a specific internal device or service. It is not required for normal outbound web browsing by office users. If the router is not correctly connected to the modem on its WAN interface, port forwarding will not restore general internet access.