350-501 Architecture Practice Question
A service provider is designing an MPLS L3VPN network to provide Layer 3 VPN services to multiple customers. Which two statements correctly describe the roles of the Provider Edge (PE) and Customer Edge (CE) routers in this architecture?
⚠ Common exam trap
Many exam-takers confuse the roles of P and PE routers, mistakenly thinking P routers store customer routes or that CE routers participate in MPLS label switching, when in fact P routers are label-switching only and CE routers are MPLS-unaware.
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
✓
PE routers advertise customer routes via MP-BGP with route distinguishers and route targets.
In an MPLS L3VPN, PE routers use MP-BGP (Multiprotocol BGP) to exchange customer VPN routes. Each VPN route is uniquely identified by a Route Distinguisher (RD) to maintain global uniqueness, and Route Targets (RTs) control the import/export of routes between VRFs. This allows the PE to separate customer routing domains while still using a shared MPLS backbone.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
P routers store all customer VPN routes in their global routing table.
Why it's wrong here
Incorrect. P routers only carry IGP and MPLS labels; VPN routes are stored only on PE routers.
- ✗
CE routers perform MPLS label switching between PE routers.
Why it's wrong here
Incorrect. MPLS label switching is done by P routers; CE routers typically do not participate in MPLS.
- ✓
PE routers advertise customer routes via MP-BGP with route distinguishers and route targets.
Why this is correct
Correct. MP-BGP is used to distribute VPNv4 routes with RD and RT.
- ✗
CE routers participate in the service provider's IGP to exchange loopback addresses.
Why it's wrong here
Incorrect. CE routers are not part of the SP IGP; they exchange routes with PE via eBGP or static.
- ✓
PE routers maintain separate VRF tables for each customer VPN.
Why this is correct
Correct. VRFs isolate customer routing tables on the PE.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
Related to this question
About these practice questions
This 350-501 question is part of Courseiva's 971-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 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 350-501 exam.