300-435: Automating and Programming Cisco Enterprise Solutions

An engineer needs to give an AI agent reverse-DNS capability so it can map IP addresses to hostnames when summarizing incidents. The engineer must implement a FastMCP tool that resolves PTR records with socket.gethostbyaddr and expose it through stdio for MCP clients. Construct the artifact by dragging the code snippets into the boxes. Not all options are used.

from mcp.server.fastmcp import 
import socket

mcp = FastMCP("dns-tools")

@mcp.()
def reverse_dns(ip: str) -> str:
    """Return primary hostname for an IP address (PTR)."""
    try:
        name, _, _ = socket.gethostbyaddr(ip)
        return name
    except Exception as e:
        return f"lookup failed: {e}"

if __name__ == "__main__":
    mcp.(="stdio")