Exam JN0-348 topic 1 question 2 discussion

"All intermediary devices must have a route to the tunnel endpoints" I just got this from Juniper JNCIS-ENT material and it says "Endpoints" in plural so the correct answer should be B

Tunnels are unidirectional, the intermediate devices must know a route to the destination tunnel address for A to B direction, the opposite direction tunnel B to A must know a route to the destination tunnel address. C is the correct answer.

"All intermediary devices must have a route to the tunnel endpoints"

Just a remark to Wauzer's commentary: It is a trick question because IP internetworks are based on a per-hop routing paradigm. IP-IP tunnels are only a special case in regard to original source and destination addresses being temporarily replaced and encapsulated. Therefore, intermediate systems must have destination routing visibility only, since packet (and frame) delivery is resolved locally. There are two exceptions (one unrelated to the topic at hand), such as reverse path checkups and if the system in not an intermediate host but either the tunnel initiator or the headend.

The intermediary devices, located in the forwarding path between the tunnel endpoint, must be able to route between the tunnel endpoints This was also taken from the training material

To form a tunnel you need 3 things, Tunnel Source, Tunnel Destination and IP. so the intermediary devices need to have a route to both.

A tunnel is per direction. For having bidirectional communication, two tunnels are required. So you need the destination only -> C

correct

Intermediary devices need to have a route to both tunnel endpoints. Answer B is correct

A-symmetric routing case. route to source IP is not required.

The answere should be B, if answere is C then how retunr traffic is travers without tunnel source ip information?