220-1101 Question 129
Single answerAccess pointsA small office recently replaced its wireless router with a business-class wireless access point connected to the existing network switch. After the change, employees can connect to the SSID, but many of them receive an APIPA address (169.254.x.x) and cannot reach the internet or file server. Wired users on the same switch are working normally. Which of the following is the MOST likely cause?
- A
The access point is using the wrong WPA3 passphrase
- B
The access point is connected to the switch using the wrong Ethernet cable type
- C
The access point is not properly bridged to the wired LAN or is connected to the wrong VLAN
- D
The access point is broadcasting on both 2.4 GHz and 5 GHz bands
Show answer and explanation
Correct answer: C
Explanation
The key troubleshooting clue is the APIPA address range (169.254.0.0/16), which Windows devices self-assign when they cannot contact a DHCP server. Because wired devices on the same switch are operating normally, the most likely fault lies in how the access point is integrated into the wired network rather than in the DHCP server itself. In real deployments, this often means the AP is connected to the wrong VLAN, the SSID is mapped incorrectly, or the AP is not bridging client traffic to the proper LAN segment. CompTIA A+ Core 1 expects technicians to recognize that access points provide wireless connectivity to an existing network and must be correctly connected and configured to pass client traffic to services such as DHCP, DNS, file shares, and internet gateways. This aligns with standard network troubleshooting best practices: verify physical connection, confirm switch port/VLAN configuration, validate DHCP reachability, and test client IP assignment.
- A. Incorrect.
Incorrect. If the WPA3 passphrase were wrong, clients generally would fail authentication and would not successfully join the wireless network. In this scenario, users are able to connect to the SSID, which indicates association is occurring. The issue appears after connection, when clients fail to obtain valid IP configuration.
- B. Incorrect.
Incorrect. Modern switches and access points typically support auto-MDI/MDIX, so straight-through versus crossover cable problems are uncommon in current environments. Also, if the Ethernet uplink were fundamentally wrong, the AP would often lose connectivity entirely, not selectively allow wireless association while preventing DHCP access.
- C. Correct.
Correct. APIPA addresses indicate clients are not receiving a lease from a DHCP server. Since wired users on the same switch are functioning normally, the DHCP service is likely available on the wired network. A common cause is that the access point is not properly bridging wireless traffic onto the correct LAN segment, or its uplink switch port is assigned to the wrong VLAN, preventing wireless clients from reaching DHCP and other network resources.
- D. Incorrect.
Incorrect. Broadcasting both 2.4 GHz and 5 GHz is a normal and common access point configuration. While band selection can affect speed, compatibility, and interference, it does not by itself cause clients to receive APIPA addresses if the network is otherwise configured correctly.