In cases where VPN customers use OSPF and have cross domain links to other sites which also connected into the provider network what is true about this situation?
A.
The OSPF tag field can be set to prevent cross domain routing loops.
B.
This configuration is not supported by MPLS VPN’s.
C.
The down bit can be used to prevent cross domain routing loops.
D.
The down bit will be reset as routes pass between OSPF domain and may cause routing loops.