Exam 300-730 topic 1 question 131 discussion

If the Phase 1 and Phase 2 tunnels have been successfully established between Site A and Site B, and pings from internal devices at Site B reach the Site B router but are not decrypted, the issue might be related to the firewall in front of the Site B router. In this case, to ensure bidirectional communication between the two sites, you need to allow the encapsulating security payload (ESP) protocol through the firewall. Therefore, the correct action would be to "Allow protocol ESP on the firewall in front of the Site B router." ESP (Encapsulating Security Payload) is a protocol used in IPsec to provide encryption, integrity, and authentication of packets. If ESP traffic is blocked by the firewall, it can prevent the successful decryption of packets arriving at Site B. AH (Authentication Header) is another IPsec protocol, but it does not provide encryption and is less commonly used. In a typical IPsec configuration, ESP is used for encryption and authentication, so allowing ESP is usually the correct step to ensure the bidirectional communication is successful.

C is correct answer

Why the answer is C? It says "successfully established a Phase 1 and Phase 2 tunnel between two sites" Doesn't that mean ESP or AH already allowed?

Not sure. Decrypt packets counter not increasing in one side might be routing issue.