What is a Diffie-Hellman key, and how does it work?
There are many different technologies used to implement, manage, and utilize VPN. As a VPN professional, you are expected to know most of these and define them. If, for some reason, you're unfamiliar with the technology that the interviewer asks you about, immediately admit this and then describe how you would go about locating the information. When discussing these technologies, you may want to compare and contrast them and even provide an example of how they illustrate your answer.
"A Diffie-Hellman Key is a public key use for encryption within a virtual private network or VPN. This key is used in conjunction with a private key to encrypt the transmission over the network. When setting up a transmission, each side exchanges the public Diffie-Hellman Key and creates a shared key using RSA. The keys are then used to send the transmission. Even if the public key is intercepted, the intruder cannot read the transmission without the private key."
