What is the function of the multicast Reverse Path Forwarding check?

Refer to the exhibit. An engineer is designing an OSPF network for a client. Requirements dictate that the routers in Area 1 should receive all routes belonging to the network, including EIGRP, except the ones originated in the RIP domain. Which action should the engineer take?

Refer to the exhibit. Area 10 is a regular OSPF area and networks 10.1.1.0/24 and 172.16.1.0/24 are internal.
Which design provides optimal routing between both networks when the link between routers C and E fails?

A company's security policy requires that all connections between sites be encrypted in a manner that does not require maintenance of permanent tunnels. The sites are connected through a private MPLS-based service that uses a dynamically changing key and spoke-to-spoke communication. Which type of transport encryption must be used in this environment?

A customer's environment includes hosts that support IPv6-only. Several of these hosts must communicate with a public web server that has only IPv4 domain name resolution. Which solution should the customer use in this environment?