CCSM Advanced VPN Troubleshooting Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Enable Perfect Forward Secrecy (PFS) on the community to force stronger Phase 2 keys.

  Why it's wrong here

  PFS affects key derivation for Phase 2 by performing an additional Diffie-Hellman exchange, but it does not change the encryption or hash algorithms used to protect data. Enabling PFS does not resolve an algorithm mismatch between peers; both peers must still agree on the same Phase 2 encryption and integrity algorithms.

• ✗

  Recreate the VPN community and select 'Traditional mode' instead of 'Simplified mode'.

  Why it's wrong here

  Traditional mode is used for legacy, rule-based VPN configurations and is not the appropriate fix for a community-based VPN algorithm mismatch. Recreating the community does not automatically change the Phase 2 algorithms to AES-256/SHA-256; the administrator would still need to configure the correct encryption and hash values.

• ✗

  Change the Phase 1 IKE proposal to AES-256/SHA-256 and reinstall the policy.

  Why it's wrong here

  Phase 1 (IKE Main Mode) governs the management SA used for key exchange; it is separate from the Phase 2 IPsec SA that protects data. The failure occurs in Quick Mode, which negotiates data encryption and hashing. Altering Phase 1 algorithms will not fix a Phase 2 mismatch and could disrupt the already successful Phase 1 negotiation.

• ✓

  Modify the IPsec VPN community's Phase 2 encryption and hash algorithms to AES-256 and SHA-256, then install policy.

  Why this is correct

  Phase 2 (Quick Mode) proposals are derived from the IPsec VPN community settings. Changing the community's encryption/hash to AES-256/SHA-256 aligns the Check Point gateway with the third-party peer's requirement, allowing the Quick Mode SA to be established. After updating the community, installing the security policy pushes the new Phase 2 properties to the gateway.