300-410 Layer 3 Technologies Practice Question
A network engineer is configuring MPLS Layer 3 VPN on a Cisco IOS XE router. The engineer wants to enable the router to distribute VPNv4 prefixes to its PE peers. Which command must be configured under the BGP routing process to enable the address family?
⚠ Common exam trap
Watch out — candidates often confuse the VRF-specific IPv4 address family with the VPNv4 address family that is used between PE routers.
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
To enable the distribution of VPNv4 prefixes in MPLS L3VPN, the engineer must configure the address-family vpnv4 command under the BGP routing process. This enters the VPNv4 address family configuration mode, where neighbors can be activated and other parameters set. The other address families do not handle VPNv4 prefixes: ipv4 vrf is for VRF-specific routing, ipv4 unicast is for global IPv4, and vpnv6 is for IPv6 VPNs.
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 vrf
Why it's wrong here
The address-family ipv4 vrf command is used to enter the VRF-specific IPv4 address family configuration mode. It is used to configure routing within a VRF, not to exchange VPNv4 prefixes between PE routers. While it is part of MPLS L3VPN, it does not enable the VPNv4 address family. Therefore, it is not the correct command for distributing VPNv4 prefixes.
- ✗
address-family ipv4 unicast
Why it's wrong here
The address-family ipv4 unicast command is used for global IPv4 unicast routing. It does not support VPNv4 prefixes, which include a route distinguisher. Enabling this address family would allow the exchange of standard IPv4 routes, but not VPNv4 routes. Thus, it is not the correct choice for MPLS L3VPN VPNv4 prefix distribution.
- ✗
address-family vpnv6
Why it's wrong here
The address-family vpnv6 command is used for IPv6 VPNs over MPLS, not for VPNv4. It would enable the exchange of VPNv6 prefixes, which are not relevant to the scenario. Since the engineer is working with VPNv4 prefixes, this command is incorrect. The correct address family for IPv4 VPNs is vpnv4.
- ✓
address-family vpnv4
Why this is correct
The address-family vpnv4 command enters the VPNv4 address family configuration mode. Within this mode, the engineer can activate neighbors and configure other VPNv4-specific parameters. Without this, the router cannot exchange VPNv4 prefixes with other PE routers. This is the correct command to enable the address family for MPLS L3VPN.
Go deeper
Related to this question
Learn chapter
Infrastructure Services: DHCP, NAT, and IPv6
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.
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.
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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.