quick dnspython usage reference

dnspython.py

# https://github.com/rthalley/dnspython
# pip install dnspython

# NOTE reverse DNS lookups on Docker seem to be failing with Docker versions between ~18.6 and ~19.03.8, as of 2020-05-13
# This generates errors like:
# `The DNS response does not contain an answer to the question: 9.8.7.6.in-addr.arpa. IN PTR`
# Workaround: start containers with external DNS where possible using the --dns flag in 'docker run'

import dns.resolver
import sys

def lookup(domain, lookup_type='a', resolver=None):
    # resolver is an instance of dns.resolver.Resolver. Use if you need to override default config.
    
    if lookup_type.lower() == 'ptr':
        # Convenience functions for reverse lookup handling IP input as ipaddress or string types
        if 'ipaddress' in sys.modules and isinstance(domain, ipaddress.IPv4Address):
                domain = domain.reverse_pointer
        elif isinstance(domain, str) and '.in-addr.arpa' not in domain:
            # assume input is an IP and generate the reverse hostname, e.g., 9.8.7.6.in-addr.arpa.
            ### todo: regex check to make sure input looks like an IP
            domain = dns.reversename.from_address(domain)
        
    try:
        if resolver is not None:
            result = resolver.query(domain, lookup_type)
        else:
            result = dns.resolver.query(domain, lookup_type)
    except dns.exception.DNSException as e:
        if isinstance(e, dns.resolver.NXDOMAIN):
            result = ['NXDOMAIN']
        elif isinstance(e, dns.resolver.NoAnswer):
            result = ['NoAnswer']
        else:
            print("error:", e)
            result = []
        
    return [str(i) for i in result]
  
print(lookup('gmail.com', 'mx'))
# > ['5 gmail-smtp-in.l.google.com.', '30 alt3.gmail-smtp-in.l.google.com.', '20 alt2.gmail-smtp-in.l.google.com.', '40 alt4.gmail-smtp-in.l.google.com.', '10 alt1.gmail-smtp-in.l.google.com.']


# using a custom nameserver other than the default loaded from /etc/resolv.conf:
rslv = dns.resolver.Resolver()
rslv.nameservers = ['1.1.1.1']
# ... lookup('gmail.com', 'mx', resolver=rslv)

# or to point it at an /etc/resolv.conf style file to load config from:
rslv = dns.resolver.Resolver(filename='/path/to/custom/resolv.conf', configure=True)

Hi friends,

I am new to dnspython, I would like to write a script that can delete, add or update old >> to new dns records for my network devices.
anyone has a demo code that I could use eventually?

Thank you,