单选题Which attribute is required for all IKE phase 2 negotiations？（）A proxy-IDB preshared keyC Diffie-Hellman group keyD main or aggressive mode
题目
单选题
Which attribute is required for all IKE phase 2 negotiations？（）
A
proxy-ID
B
preshared key
C
Diffie-Hellman group key
D
main or aggressive mode