Routing & Switching test (Intermediate)

Sample questions

5 sample questions from the Routing & Switching test, with the answers. Samples are taken out of the live test, so you will not meet these when you sit it.

1. In a network configuration where a trunk port is set with a native VLAN, what is the correct behavior and potential risk associated with the native VLAN traffic?

   1. The native VLAN is the same as the default VLAN and cannot be changed.
   2. The native VLAN traffic will be untagged and may cause a security risk if not properly configured.
   3. The native VLAN is used for management traffic only and is automatically tagged.
   4. The native VLAN is used to carry tagged traffic only and is not associated with any VLAN ID.

   Answer: B. The native VLAN traffic will be untagged and may cause a security risk if not properly configured.

   The native VLAN is used to carry untagged traffic across a trunk link. If not configured properly, it can lead to security risks because traffic on the native VLAN is not tagged, which could allow unintended traffic to pass through the trunk. The other options are incorrect because they do not accurately describe the function or risks associated with the native VLAN.

2. In a scenario where a company is deploying PPPoE tunneling for broadband internet access, which of the following accurately describes the initiation of a PPPoE session?

   1. The PPPoE session is initiated by the client sending a PADI (PPPoE Active Discovery Initiation) packet to the broadcast MAC address.
   2. The PPPoE session is initiated by the client sending a PADO (PPPoE Active Discovery Offer) packet to the server's MAC address.
   3. The PPPoE session is initiated by the server sending a PADO packet to the broadcast MAC address.
   4. The PPPoE session is initiated by the server sending a PADI packet to the client's MAC address.

   Answer: A. The PPPoE session is initiated by the client sending a PADI (PPPoE Active Discovery Initiation) packet to the broadcast MAC address.

   In PPPoE tunneling, the client initiates the session by sending a PADI packet to the broadcast MAC address (00-00-5E-00-00-16) to discover the PPPoE server. This is the correct process for establishing a PPPoE session. The other options either describe incorrect roles or steps not part of the PPPoE discovery phase.

3. What configuration is required for a router-on-a-stick setup to successfully route traffic between VLANs?

   1. The VLANs must be configured on the switch's access port, and the router can be configured with a single interface.
   2. The VLANs must be configured on the router's physical interface without subinterfaces.
   3. The router must be configured with subinterfaces for each VLAN, and the VLANs must be allowed on the trunk port.
   4. The VLANs can be allowed on the access port, and the router can be configured with a single interface.

   Answer: C. The router must be configured with subinterfaces for each VLAN, and the VLANs must be allowed on the trunk port.

   For inter-VLAN routing to work, the router must be configured with subinterfaces for each VLAN, and the VLANs must be allowed on the trunk port. If the VLANs are not allowed on the trunk port, the traffic will not be forwarded. Additionally, the router-on-a-stick configuration requires subinterfaces to route traffic between VLANs.

4. Which of the following is a valid WAN optimization technique that can be implemented to improve performance over a slow WAN link?

   1. Enabling jumbo frames on the LAN side
   2. Enabling compression on the WAN link
   3. Using a higher MTU on the WAN link
   4. Configuring Quality of Service (QoS) policies

   Answer: B. Enabling compression on the WAN link

   Enabling compression on the WAN link is a valid WAN optimization technique that reduces the amount of data transmitted over the link, thereby improving performance. Using a higher MTU on the WAN link is not a valid optimization technique because it may lead to fragmentation and increased overhead. Configuring Quality of Service (QoS) policies is a valid technique for traffic prioritization, not optimization. Enabling jumbo frames on the LAN side is not a WAN optimization technique and may cause issues if not properly supported by the network infrastructure.

5. What is the best practice for configuring trunk ports on Cisco switches to ensure intentional trunking and avoid security risks?

   1. Configure the native VLAN to allow automatic negotiation.
   2. Disable DTP and set trunk mode explicitly.
   3. Leave trunk mode unconfigured and rely on default settings.
   4. Use DTP to negotiate trunking automatically.

   Answer: B. Disable DTP and set trunk mode explicitly.

   Dynamic Trunking Protocol (DTP) is used to negotiate trunking between switches. However, it is recommended to disable DTP (`switchport nonegotiate`) and set the trunk mode explicitly to avoid unintended trunking and security risks. This ensures that the trunking configuration is intentional and not dependent on negotiation.