Which protocol provides a generic tunnel transport without encryption?

The correct answer is GRE, or Generic Route Encapsulation. GRE is a tunneling protocol developed by Cisco that encapsulates a wide variety of network layer protocols into a point-to-point connection. It provides a method for wrapping packets of any protocol inside IP packets, making it possible to transport them across an IP network without needing encryption.

This feature allows GRE to create virtual point-to-point links that can be used for connecting different networks, or for other purposes such as connecting remote sites or creating VPNs. Since GRE does not incorporate encryption or authentication by itself, it is often used in combination with other protocols, such as IPSEC, to ensure secure communication.

The other options listed each have specific purposes but are inherently different from GRE. IPSEC is focused on securing data by encrypting and authenticating packets at the IP layer, while SSH is used for securely accessing remote devices and providing encrypted communication over an insecure network. HTTPS, on the other hand, is designed to secure communications over the web by using SSL/TLS protocols, ensuring both data integrity and confidentiality during transfer. None of these options serve as a generic tunnel transport without encryption in the same manner that GRE does.