When attempting to start a VPN tunnel, in the logs the error 'no proposal chosen' is seen numerous times. No other VPN-related log entries are present. Which phase of the VPN negotiations has failed?

IKE Phase 1 failures produce errors related to ISAKMP SA negotiation, authentication mismatches, or pre-shared key failures - not 'no proposal chosen'.

'IPSec Phase 2' is not a standard term; the correct designation is IKE Phase 2, which handles IPSec SA negotiation.

'IPSec Phase 1' is not a standard term; the correct designation is IKE Phase 1, which establishes the ISAKMP SA.

IKE Phase 2 (Quick Mode) is where peers negotiate IPSec Security Associations, including encryption algorithm, integrity hash, and lifetime values. The 'no proposal chosen' error means the responder found no matching transform set among those offered by the initiator, causing Phase 2 to fail. The absence of any other log entries implies Phase 1 completed successfully, isolating the failure to Phase 2.