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200-901 · Question #556

An engineer must investigate the problems on a web application and address them to related teams. The engineer verifies that the network farm serving the application is working properly and is accessi

The correct answer is D. NAT. NAT (Network Address Translation) is the root cause. The servers are reachable internally via private IP, and DNS correctly resolves public hostnames to public IPs - but those public IPs cannot reach the servers. This is a classic NAT misconfiguration: the firewall or router is n

Network Fundamentals

Question

An engineer must investigate the problems on a web application and address them to related teams. The engineer verifies that the network farm serving the application is working properly and is accessible through the internal IP address and port. Each server has a public DNS name and public IP. While name resolutions from the outside network to the public IP address are working properly too, the engineer discovers that some servers are not accessible from the public Internet. Which problem type must be addressed as the cause for the case?

Options

  • Ainternal network connectivity
  • Bblocked transport block
  • Cproxy
  • DNAT

How the community answered

(28 responses)
  • A
    4% (1)
  • B
    11% (3)
  • C
    7% (2)
  • D
    79% (22)

Explanation

NAT (Network Address Translation) is the root cause. The servers are reachable internally via private IP, and DNS correctly resolves public hostnames to public IPs - but those public IPs cannot reach the servers. This is a classic NAT misconfiguration: the firewall or router is not correctly translating inbound traffic from the public IP to the correct internal (private) IP for those specific servers. Internal network connectivity (A) is ruled out since servers are accessible internally. A blocked transport/port issue (B) would typically affect all servers equally. A proxy issue (C) typically affects outbound traffic, not inbound server accessibility.

Topics

#NAT#Network Troubleshooting#Public/Private IP Addressing#External Connectivity

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