200-901 Question 199
Single answerA developer is troubleshooting a connectivity issue between their application hosted in a private network and an external API service. The application uses HTTP on port 80 to communicate with the API, but the connection is failing. Upon investigation, the network team confirms that NAT is configured correctly for outbound traffic. What is the most likely cause of the issue?
- A
The firewall on the private network is blocking outbound traffic on port 80.
- B
The external API service is rejecting traffic from the NAT IP address.
- C
The application is attempting to use HTTPS instead of HTTP.
- D
The external API service is listening on a port other than port 80.
Show answer and explanation
Correct answer: D
Explanation
The most likely cause of the connectivity issue is that the external API service is listening on a different port than the one the application is configured to use (port 80). Even though NAT is configured correctly and there is no mention of firewall restrictions, a mismatch in the port being used for communication would result in a failure to establish a connection.
- A. Incorrect.
If the firewall were blocking outbound traffic on port 80, no traffic would leave the private network at all. However, the question states that NAT is configured correctly, which implies that outbound traffic is being routed.
- B. Incorrect.
The external API service rejecting traffic from the NAT IP address could cause issues, but this is less likely as the question does not indicate any such restrictions or rejections.
- C. Incorrect.
If the application were attempting to use HTTPS instead of HTTP, the connection would fail due to protocol mismatch, but the question explicitly states that HTTP on port 80 is being used.
- D. Correct.
If the external API service is listening on a different port, the connection will fail because the application is configured to communicate on port 80. This is the most likely cause of the issue.