You are configuring VLANs on three interconnected switches (SW1, SW2, and SW3). VLAN 10 (Data) and VLAN 20 (Voice) need to span across all three switches. SW1 has a trunk link to SW2, and SW2 has a trunk link to SW3. Which of the following configurations are necessary to ensure proper communication between devices on VLAN 10 and VLAN 20 across all switches? (Select all that apply.)
Correct Answer: A,C,E,F
Detailed Explanation: To allow VLANs to span multiple switches, several key configurations are necessary. Let's break down why each correct answer is essential and why the incorrect options are not: a) Configure VLAN 10 and VLAN 20 on SW1, SW2, and SW3: VLANs are locally significant to a switch. Even though you want VLAN 10 and 20 to exist across all three switches, each switch must be explicitly configured with these VLANs. Without this, the switches won't recognize the VLAN tags in the frames. c) Configure the links between SW1 and SW2, and SW2 and SW3 as trunk ports: Trunk ports are the backbone of VLAN communication across switches. They carry traffic for multiple VLANs simultaneously. Frames traversing a trunk link are tagged with a VLAN identifier (a number), allowing the receiving switch to identify which VLAN the frame belongs to. Access ports, in contrast, are designed for a single VLAN only. e) Assign access ports on SW1, SW2, and SW3 to either VLAN 10 or VLAN 20 as needed: This is how you connect end devices to the correct VLAN. An access port is configured to belong to a specific VLAN. Any device connected to that port will be part of that VLAN, and its traffic will be tagged accordingly when it enters the switch. f) Ensure that the native VLAN on the trunk links is consistent across all switches: The native VLAN is a special VLAN that is not tagged on a trunk link. It's used for control traffic (like STP) and some older protocols. If the native VLAN is different on two switches connected by a trunk, it can lead to problems. Frames from the native VLAN on one switch might be misinterpreted by the other switch, potentially causing spanning-tree issues or other network disruptions. It's best practice to change the native VLAN to something other than VLAN 1 for security reasons. b) Configure the links between SW1 and SW2, and SW2 and SW3 as access ports in VLAN 10: This is incorrect. Access ports are for connecting end devices, not for connecting switches that need to carry multiple VLANs. Using access ports would limit communication to only VLAN 10, preventing devices in VLAN 20 from communicating across switches. d) Configure a VTP domain on all three switches with the same password: While VTP (VLAN Trunking Protocol) can help manage VLANs, it's not strictly required for VLANs to span multiple switches. VTP propagates VLAN information between switches, but you can also configure VLANs manually on each switch. Furthermore, VTP can sometimes be a source of problems if not configured carefully. Therefore, while helpful, it's not a necessary condition for this specific scenario. Trunking and configuring the VLANs on each switch are the fundamental requirements.
This CCNA practice question helps students prepare for Cisco networking certification exams by testing knowledge of network fundamentals, routing, switching, and network security concepts.