350-401 Architecture Practice Question
A network engineer is deploying a new branch office that connects to the headquarters over an MPLS Layer 3 VPN provided by a service provider. The branch has a single CE router running eBGP with the provider PE router. The engineer wants to advertise the branch LAN prefix into the MPLS VPN while keeping the branch routing table simple. Which approach is appropriate?
⚠ Common exam trap
The trap here is thinking the customer must configure the provider PE router or use MPLS label distribution, when the customer only controls the CE side.
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
✓
Configure the CE router to redistribute the LAN prefix into eBGP toward the PE router.
In an MPLS Layer 3 VPN, the customer edge router exchanges routes with the provider edge router using a PE-CE routing protocol such as eBGP. Redistributing the branch LAN prefix into eBGP advertises it to the PE, which imports it into the correct VRF and propagates it to other VPN sites, keeping the branch routing table simple with a default route toward the provider.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure the CE router to redistribute the LAN prefix into eBGP toward the PE router.
Why this is correct
In an MPLS Layer 3 VPN, the CE router exchanges routes with the provider PE router using eBGP. Redistributing the branch LAN prefix into BGP advertises it to the PE, which places it into the correct VRF and propagates it across the provider backbone to other sites in the same VPN. This keeps the branch routing table simple because the CE only needs a default or summarized route toward the PE.
- ✗
Configure the CE router to run OSPF with the PE router and redistribute the LAN prefix into OSPF.
Why it's wrong here
While some providers offer OSPF as the PE-CE routing protocol, the scenario specifies eBGP is already running between the CE and PE. Adding OSPF alongside eBGP would create redundant routing adjacencies and complicate the branch routing table. The question asks for the appropriate approach given eBGP is in place, so introducing OSPF here is unnecessary and could cause suboptimal or conflicting routes.
- ✗
Configure a static route on the PE router pointing to the branch LAN prefix.
Why it's wrong here
Static routes on the provider PE router are the provider's responsibility, not the customer engineer's, and the customer typically has no administrative access to the PE. In an MPLS Layer 3 VPN, the customer controls only the CE side. Attempting to configure the PE would violate the provider-customer boundary and would not be a valid design approach for the customer to implement.
- ✗
Configure the CE router to send the LAN prefix using MPLS label distribution to the PE router.
Why it's wrong here
MPLS label distribution between CE and PE is not how customer prefixes are advertised in a Layer 3 VPN. The provider PE routers distribute labels for VPN routes using MP-BGP with route targets and route distinguishers, not the CE. The CE simply exchanges IP prefixes with the PE via eBGP or another PE-CE protocol; it does not participate in label distribution for the VPN.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
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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 350-401 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 350-401 exam.