200-901 Question 198
Select 3A developer reports that their application, hosted on a private network, cannot connect to an external third-party API. Upon investigation, you find out that the application uses HTTP on port 80 for communication, and the network uses NAT to translate internal IP addresses to a public IP. Which of the following could be the potential cause(s) of the connectivity issue?
- A
The NAT configuration is not properly translating the private IP address to a public IP address.
- B
The firewall is blocking outbound traffic on port 80 from the application.
- C
The third-party API is not reachable due to an ISP outage.
- D
The application is using an unsupported transport protocol for communication.
- E
The private IP address of the application is outside the NAT translation range.
Show answer and explanation
Correct answers: A, B, E
Explanation
This scenario involves diagnosing connectivity issues for an application behind a NAT. The most likely causes are improper NAT configuration, firewall rules blocking the required traffic, or the private IP being outside the NAT translation range. These issues prevent the application from reaching the third-party API. Other options like an ISP outage or unsupported protocol are less relevant given the details provided in the scenario.
- A. Correct.
If NAT is not configured properly, the private IP address of the application might not be translated to a public IP address, causing connectivity issues.
- B. Correct.
If the firewall is blocking outbound traffic on port 80, the HTTP request from the application cannot reach the third-party API.
- C. Incorrect.
While an ISP outage could theoretically cause connectivity issues, this is external to the application and NAT setup, and there is no evidence in the scenario to suggest such an outage.
- D. Incorrect.
The application uses HTTP, which is a supported transport protocol. This is not a likely cause of the issue mentioned.
- E. Correct.
If the application's private IP address is outside the NAT translation range, NAT will not translate the address, leading to connectivity problems.