CompTIA Network+ (N10-008) — Question 391

Which of the following situations would require an engineer to configure subinterfaces?

Answer options

• A. In a router-on-a-stick deployment with multiple VLANs
• B. In order to enable inter-VLAN routing on a multilayer switch
• C. When configuring VLAN trunk links between switches
• D. After connecting a router that does not support 802.1Q VLAN tags

Correct answer: A

Explanation

The correct answer is A because a router-on-a-stick configuration requires subinterfaces to handle traffic from multiple VLANs over a single physical interface. Option B is incorrect as inter-VLAN routing on a multilayer switch does not require subinterfaces; it uses VLAN interfaces instead. Option C is also incorrect since VLAN trunk links between switches do not necessitate subinterfaces but rather require trunking configurations. Option D is wrong because connecting a router that does not support 802.1Q would not involve subinterfaces.