300-410 Infrastructure Services Practice Question
A network engineer is configuring a Cisco router to support MPLS Layer 3 VPNs. The engineer needs to enable the router to exchange VPNv4 routes with a provider edge (PE) router. Which address family must be configured under the BGP routing process to support this?
⚠ Common exam trap
A common mix-up: candidates confuse the per-VRF IPv4 address family with the VPNv4 address family used for PE-to-PE route exchange.
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
✓
address-family vpnv4 unicast
MPLS Layer 3 VPNs rely on BGP VPNv4 address family to exchange VPN routes between PE routers. The VPNv4 address family carries the route distinguisher and route target attributes that identify the VPN membership. Other address families serve different purposes, such as IPv4 unicast for global routing or IPv4 VRF for per-VRF routing, but not for PE-to-PE VPN route exchange.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
address-family ipv4 unicast
Why it's wrong here
The IPv4 unicast address family is used for standard IPv4 unicast routing and does not carry the VPNv4 specific attributes such as route distinguishers and route targets. While it may be used for the underlying transport, it does not support MPLS Layer 3 VPN route exchange. Therefore, it is not the correct choice for VPNv4 routes.
- ✗
address-family ipv6 unicast
Why it's wrong here
The IPv6 unicast address family is used for IPv6 routing and is not relevant to MPLS Layer 3 VPNs that use VPNv4 routes. While there is a VPNv6 address family for IPv6 VPNs, this scenario specifically requires VPNv4 for IPv4 VPN routes. Therefore, this option is incorrect.
- ✓
address-family vpnv4 unicast
Why this is correct
The VPNv4 unicast address family is specifically designed to carry MPLS Layer 3 VPN routes. It includes the route distinguisher and route target extended communities necessary for VPN segmentation. Configuring this address family under BGP allows the PE routers to exchange VPNv4 prefixes, enabling MPLS L3VPN functionality. This is the correct address family for this scenario.
- ✗
address-family ipv4 vrf
Why it's wrong here
The IPv4 VRF address family is used within a VRF context to exchange IPv4 routes for a specific VPN. However, it is not used for the PE-to-PE exchange of VPNv4 routes. The VPNv4 address family is required for that purpose. The IPv4 VRF address family is configured per VRF and does not carry the VPNv4 attributes needed for MPLS L3VPN.
Go deeper
Related to this question
Learn chapter
MPLS L3VPN Basics
Key term
MP-BGP for VPN
MP-BGP for VPN is an extension of the Border Gateway Protocol that carries multiple types of network layer information to enable scalable, isolated virtual private networks over a shared provider infrastructure.
Key term
MPLS Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.