What happens, by default, when the GlobalProtect app fails to establish an IPSec tunnel to...

The GlobalProtect VPN solution by Palo Alto Networks is designed to provide secure remote access to users. It primarily attempts to establish a VPN tunnel using the IPSec protocol for optimal security and performance. However, in cases where IPSec cannot be used due to network restrictions or other issues, GlobalProtect has a fallback mechanism.

C. It tries to establish a tunnel to the GlobalProtect gateway using SSL/TLS:

If the GlobalProtect app fails to establish an IPSec tunnel with the GlobalProtect gateway, the default behavior is to fallback to SSL/TLS for tunnel establishment. This ensures that the VPN connection can still be established, maintaining secure remote access for the user even in environments where IPSec is not feasible. SSL/TLS provides a secure tunnel, albeit generally with slightly less efficiency than IPSec.

This fallback mechanism is part of the GlobalProtect app's design to ensure reliability and continuous secure access for remote users under various network conditions.