What is the most typical use of an overlapping VPN?

A.
Service providers supporting managed CE services.

B.
Service providers supporting carrier-over-carrier MPLS implementations.

C.
Simple intranet VPN implementations.

D.
Companies that use MPLS VPNs to implement both intranet and extranet services.

Explanation:

There are two typical uses for overlapping VPNs:
1) Companies that use MPLS VPNs to implement both intranet and extranet services might use overlapping VPNs. In this scenario, each company participating in the extranet VPN would probably deploy a security mechanism on its customer edge (CE) routers to prevent other companies participating in the VPN from gaining access to other sites in other customer VPN
2) A security-conscious company might decide to limit visibility between different departments in the organization. Overlapping VPNs might be used as a solution in this case
Reference: Cisco Press – Implementing Cisco MPLS study guide p.6-20