I have a question that is related to networking. On Receiver, when Layer 3 receives the message from Layer 2, the number of headers, including encapsulated headers in the message is [3], while the outermost header is a Layer [FILL HERE] header. My question is what is the layer header for the outermost header? Is it a Layer[3] header?

Also, another question, when assembling received Layer-3 messages into a Layer-4 message, can Receivers Layer 3 sort the Layer-3 messages in the same order as it has received them from Layer 2, its underneath layer?