以编程方式确定Web域是否可用的最有效方法？

import socket
import time

def dns_check(url):
    try:
        socket.create_connection((url, 443), 2).sendall(b"HTTP/1.1 200 OK\r\n" + b"Content-Type: text/plain\r\n\r\n")
        timeout = time.time() + 5
        while True:
            data = socket.recv(4096, socket.CMSG_CLOEXEC)
            if data:
                if b"Name":
                    return True
            time.sleep(0.2)
            if time.time() > timeout:
                return False
    except Exception:
        return False

# Test:
url = "https://www.google.com"

if dns_check(url):
    print(f"Domain '{url}' is available.")
else:
    print(f"Domain '{url}' is not available.")