Is it precise to use `requests` to check if a domain name is registered?

Question

I noticed that requesting an invalid url requests.get(invalid_url) throws the following exceptions:

Traceback (most recent call last):
  File "/usr/lib/python3.4/socket.py", line 530, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -2] Name or service not known

During handling of the above exception, another exception occurred:
  File "/usr/lib/python3/dist-packages/urllib3/connectionpool.py", line 607, in urlopen
    raise MaxRetryError(self, url, e)
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='sparkandshine.me', port=80): Max retries exceeded with url: / (Caused by <class 'socket.gaierror'>: [Errno -2] Name or service not known)

During handling of the above exception, another exception occurred:
  File "/usr/lib/python3/dist-packages/requests/adapters.py", line 378, in send
    raise ConnectionError(e)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='sparkandshine.me', port=80): Max retries exceeded with url: / (Caused by <class 'socket.gaierror'>: [Errno -2] Name or service not known)

Is it precise to determine whether a domain name is registered or not by catching those exceptions? Here is the source code:

#!/usr/bin/env python3
import http
import urllib3
import requests

url = 'http://example.com'
try :
    r = requests.get(url)
except (http.client.HTTPException, urllib3.exceptions.MaxRetryError, requests.exceptions.ConnectionError):
    print(url) #this domain name is not registered?

Answer 1

No; it is perfectly fine for a domain to be registered and not have an IP address for the root domain name, let alone have a server run on port 80 of that IP address.