220-1101 Networking Practice Question
A technician connects a new workstation to a managed switch port. The workstation receives an IP address from the DHCP server and can ping its own IP address, but it cannot ping any other devices on the local network, including the default gateway. The technician verifies that the Ethernet cable is functional and that the link lights are solid on both the NIC and the switch port. Which of the following is the MOST likely cause of this issue?
⚠ Common exam trap
The trap here is that candidates often blame the DHCP server or IP configuration because the workstation gets an IP, but they overlook that Layer 2 VLAN misconfiguration can allow DHCP to work while blocking all other local traffic.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The switch port is configured with an incorrect VLAN assignment.
The workstation receives an IP address and can ping itself, confirming Layer 3 configuration is functional. However, it cannot ping other devices on the local network, including the default gateway. Since the cable and link lights are good, the issue is at Layer 2. An incorrect VLAN assignment on the switch port isolates the workstation into a different broadcast domain, preventing it from communicating with devices in the correct VLAN, including the gateway.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The switch port is configured with an incorrect VLAN assignment.
Why this is correct
A mismatched VLAN isolates the workstation into a separate broadcast domain. DHCP may still work via a helper address, but the workstation cannot communicate with devices in other VLANs, including the default gateway, unless inter-VLAN routing is explicitly configured.
- ✗
The workstation's network adapter is set to half-duplex.
Why it's wrong here
Duplex mismatch can cause severe performance degradation and packet loss, but it typically still allows some communication, such as obtaining an IP address. It would not completely prevent pinging the default gateway if the link is established.
- ✗
The DHCP server has excluded the workstation's MAC address.
Why it's wrong here
A DHCP server MAC exclusion prevents the server from leasing an IP to that specific MAC address. Consequently, the workstation would either receive no IP configuration or fall back to an Automatic Private IP Addressing (APIPA) address in the 169.254.0.0/16 range, which is not routable and cannot reach the default gateway. Since the scenario implies the workstation has an IP address and can attempt communication, a DHCP exclusion is not the cause; and if the workstation had a static IP, DHCP exclusion would have no effect whatsoever.
- ✗
The default gateway is not configured on the switch.
Why it's wrong here
The default gateway is typically configured on a router or a Layer 3 switch acting as a router, not on a basic managed switch. Even if a default gateway is missing on a Layer 3 switch, it would not prevent pinging the gateway IP because the gateway is a separate device; the workstation needs to reach that IP, which requires proper VLAN membership.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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