curl is powerful command-line tool which can be used to test download speed, check headers, connection and everything else related to http operations.
You can use it to verify your headers or test the download speed.
With the following command you can get only the response headers and thus verifying if everything is configured properly:
curl -I ucdn.com
You can check download speed with the command below:
curl -o /dev/null ucdn.com
For more details check:
curl -h or curl --help