The application's failure to populate information suggests a connectivity issue with the database server. curl is a command-line tool for transferring data using various network protocols. It can be used to test connectivity to a specific server and port, which is essential for diagnosing if the database service is accessible from the client machine. By attempting a connection to the server's IP address and the database's specific port (e.g., curl -v telnet://serverip:port), a technician can quickly verify if the port is open and listening. This makes curl the most direct and effective troubleshooting tool among the choices for this specific problem.

A. ipconfig: This command displays the local machine's IP configuration. It does not test connectivity to a remote server or a specific service port.

B. nslookup: This tool is used for DNS queries to resolve hostnames to IP addresses. It does not verify if the host is reachable or if a service is running.

C. netstat: This command shows active network connections and listening ports on the local machine. It does not actively test the ability to establish a new connection to a remote server.

1. curl project documentation: The official documentation describes curl's capabilities

including its use with the TELNET protocol to test port connectivity. "curl is a tool to transfer data from or to a server

using one of the supported protocols... TELNET..."

Source: Stenberg

D. (2023). curl - Manual. curl project. Retrieved from https://curl.se/docs/manpage.html (See protocol descriptions).

2. Microsoft Command-line reference: Microsoft's documentation for curl

which is included in modern Windows operating systems

outlines its syntax and use for transferring data from a server

which implicitly includes testing the connection to that server's service.

Source: Microsoft. (2023). curl command-line tool. Microsoft Learn. Retrieved from https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/curl.

3. University Courseware on Network Tools: Computer networking courses frequently teach the use of command-line utilities for diagnostics. curl and telnet are standard tools for verifying application-layer connectivity to a specific port.

Source: Kurose

J.

& Ross

K. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 2

"Application Layer

" discusses client-server interactions and the tools used to debug them

such as Telnet

which curl can emulate.