Which of the following is incorrect about IKE V1 and IKE V2?

Note: To establish a pair of IPSec, IKE V1 needs to go through two phases: "main mode + fast mode" or "barbaric mode + fast mode". The former needs to exchange at least 9 messages, and the latter requires at least 6 messages. In IKE V2, an IKE SA and a pair of IPSecs can be completed by using a total of four messages in two exchanges. If the required IPSec SA is greater than 1 pair, the first pair of SAs only needs to add 1 additional exchange, that is, 2 messages can be completed. This is much easier than IKE V1. IKE V2 defines three types of exchanges: initial exchange, creation of SA exchange, and notification exchange.