easyMultiple Choice
350-401 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show vrf brief
Name Default RD Protocols Interfaces CUSTOMER_A 65000:100 ipv4 Gi0/0.100 CUSTOMER_B 65000:200 ipv4 Gi0/0.200 MANAGEMENT 65000:999 ipv4 Gi0/1
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the distinction between VRF-lite and MPLS L3VPN; the trap here is that candidates assume any VRF configuration implies MPLS is running, but the show vrf brief output alone does not confirm MPLS—it only shows VRF definitions and interface bindings.
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
✓
CUSTOMER_A and CUSTOMER_B are on the same physical interface but different subinterfaces.
The output shows that both CUSTOMER_A and CUSTOMER_B are associated with subinterfaces Gi0/0.100 and Gi0/0.200, which are subinterfaces of the same physical interface Gi0/0. This is a common design for MPLS L3VPN or VRF-lite deployments where multiple VRFs share a single physical link using 802.1Q VLAN tagging.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All VRFs are using the same route distinguisher.
Why it's wrong here
This is incorrect because the configuration excerpt explicitly shows each VRF with a unique route distinguisher: CUSTOMER_A uses 65000:100, CUSTOMER_B uses 65000:200, and MANAGEMENT uses 65000:999. In VRF deployments, the RD is used to maintain uniqueness of IPv4 prefixes even when overlapping addresses exist across VRFs, so seeing distinct RDs directly refutes the claim. The statement would only be true if all VRFs shared a single RD value, which they do not.
- ✗
The MANAGEMENT VRF is used for customer traffic.
Why it's wrong here
The MANAGEMENT VRF is specifically created for out-of-band control-plane access, such as SSH, SNMP, or syslog, and is intentionally isolated from customer data traffic. In the output, the VRF named MANAGEMENT is a dedicated administrative routing table, not a payload-carrying VRF for subscribers or tenants. Customer traffic is instead associated with CUSTOMER_A and CUSTOMER_B, which are bound to subinterfaces on Gi0/0, while the MANAGEMENT VRF would be reachable via a separate management interface or loopback, not via those customer-facing subinterfaces.
- ✓
CUSTOMER_A and CUSTOMER_B are on the same physical interface but different subinterfaces.
Why this is correct
The correct interpretation is that CUSTOMER_A and CUSTOMER_B each use a subinterface on the same physical GigabitEthernet0/0 port: CUSTOMER_A is configured on Gi0/0.100 and CUSTOMER_B on Gi0/0.200. This is a classic VRF-lite design, where 802.1Q VLAN tags on trunk subinterfaces allow one physical link to carry traffic for multiple VRFs, with each subinterface mapped to a separate VRF. Segmenting customer traffic onto different subinterfaces of the same physical interface preserves isolation while reducing hardware port consumption.
- ✗
The router is running MPLS L3VPN.
Why it's wrong here
The presence of VRFs alone does not prove MPLS L3VPN operation, and this output shows no MPLS signaling protocols (e.g., LDP, TDP, RSVP-TE) or BGP VPNv4 address-family configuration. In an MPLS L3VPN, VRFs are combined with MPLS labels and MP-BGP VPNv4 routes to provide Layer 3 connectivity across the service provider backbone. Since the provided output contains only VRF definitions and subinterface assignments, the deployment could equally be VRF-lite, where VRFs are used locally without MPLS or VPNv4 exchange, making this statement unsupported.
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Related to this question
Learn chapter
QoS and Network Performance Management
Key term
VLAN Trunking
VLAN Trunking is a method to carry traffic for multiple VLANs over a single network link between switches or between a switch and a router.
Key term
Virtual Routing and Forwarding
Virtual Routing and Forwarding (VRF) is a technology that allows a single physical router to operate like multiple independent routers by keeping separate routing tables and forwarding decisions for each instance.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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