Which of the following protocols would MOST likely be used in the establishment of an IPSec VPN tunnel?

AES is a symmetric encryption algorithm used to protect data inside an already-established tunnel, not to establish the tunnel itself.

TKIP is a key management protocol used in WPA wireless security and has no role in IPSec VPN tunnel establishment.

802.1q is an IEEE standard for VLAN tagging on Ethernet networks and is unrelated to VPN tunneling or IPSec.

ISAKMP (Internet Security Association and Key Management Protocol) is the framework used by IKE (Internet Key Exchange) to establish, negotiate, modify, and delete security associations for IPSec tunnels. It defines the procedures for authenticating peers and creating session keys before encrypted traffic can flow through the tunnel.