@RUCHIKUMARI 

To check if an API is up or down in Pega 8.5.6 in Pega Cloud, you can use any REST client tool like Postman or cURL to send a GET request to the API endpoint URL.

For example, to check the status of the API endpoint URL "https://hostname/prweb/api/ApplicationAPI/Work/CreateNewFlow", you can send a GET request to that URL using a REST client tool. If the API is up and running, you should receive a response with an HTTP status code 200 OK. If the API is down, you may receive an HTTP status code 404 Not Found or 500 Internal Server Error, depending on the reason for the failure.

Additionally, you can also monitor the logs in Pega to check for any error messages related to the API. If there are any issues with the API, the logs may provide more details about the cause of the issue. You can access the logs in the Pega Cloud management console or through Pega's DevOps pipeline.

Finally, you can also set up monitoring and alerting for the API using tools like Pega Predictive Diagnostic Cloud (PDC) or other third-party monitoring tools. These tools can help you proactively monitor the health of your API and alert you in case of any issues.

@RUCHIKUMARI 

You can use Postman to check if an API is down by sending a request to the API and observing the response. Here are the steps:

1. Open Postman and create a new request by clicking the "New" button in the top left corner.
2. Enter the URL of the API you want to check in the "Enter Request URL" field.
3. Choose the appropriate HTTP method (e.g. GET, POST, PUT) from the dropdown menu.
4. Click the "Send" button to send the request.
5. Look at the response in the "Response" section of the screen. If the API is down, you may see an error message or a timeout message indicating that the request could not be completed.

If you receive an error message, check the status code to get more information about the error. A status code in the 4xx or 5xx range typically indicates an error. 

hope if helps!!!