Network Address Translation (NAT) on the firewall is responsible for translating the public IP address to the private IP addresses of internal servers. If traffic is being forwarded to the wrong server, it indicates a misconfiguration in the NAT rules.
NAT Configuration: NAT rules need to be correctly configured to forward traffic to the appropriate internal server based on the destination IP and port.
Misconfiguration: If NAT rules are incorrect, traffic may be directed to the wrong internal IP address, as seen in the exhibit where traffic is sent to server 1 instead of server 2.
Option D is correct as the issue is caused by NAT misconfiguration on the firewall.
Reference:
Cisco DevNet Documentation: Configuring NAT