300-410 Layer 3 Technologies Practice Question
A network engineer is implementing MPLS Layer 3 VPNs. The engineer wants to ensure that customer routes are propagated across the MPLS core. Which protocol is typically used within the provider core to distribute VPNv4 routes?
⚠ Common exam trap
Watch out — candidates often confuse the underlay routing protocol (which could be OSPF or EIGRP) with the protocol used for VPNv4 route distribution; MP-BGP is specifically designed for this purpose.
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
✓
BGP
In MPLS Layer 3 VPNs, Multiprotocol BGP (MP-BGP) is used to distribute VPNv4 routes between provider edge routers. MP-BGP carries the VPNv4 address family, which includes the route distinguisher and route target extended communities, along with MPLS labels. This allows the provider core to forward customer traffic based on labels.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
BGP
Why this is correct
Multiprotocol BGP (MP-BGP) is used to distribute VPNv4 routes across the MPLS core. It carries the VPNv4 address family and associated MPLS labels (route targets and route distinguishers). Provider edge routers establish iBGP sessions to exchange VPNv4 reachability information, enabling MPLS L3 VPNs.
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OSPF
Why it's wrong here
OSPF is an interior gateway protocol used for routing within a single autonomous system. It does not natively support VPNv4 address families or MPLS labels. While OSPF can be used for underlay routing in the core, it is not used to distribute VPNv4 routes.
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LDP
Why it's wrong here
Label Distribution Protocol (LDP) is used to distribute MPLS labels for IPv4 prefixes, but it does not distribute VPNv4 routes. LDP is used for establishing label-switched paths for the core, but VPNv4 route exchange requires MP-BGP.
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EIGRP
Why it's wrong here
EIGRP is a Cisco advanced distance-vector routing protocol. It does not support VPNv4 address families or MPLS label distribution. It can be used as an underlay routing protocol in the core, but not for VPNv4 route propagation.
Go deeper
Related to this question
Learn chapter
Device Management and Network Monitoring (SNMP, Syslog, NetFlow)
Key term
LDP Protocol
LDP, or Label Distribution Protocol, is a protocol that routers use to automatically exchange labels that enable MPLS (Multiprotocol Label Switching) to create fast, efficient paths for data packets across a network.
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.