A simple function that takes a domain, finds NS records, resolves their IP, and attempts a DNS Zone Transfer with dnspython.

dns-zone-transfer.py

#!/bin/python3
# A Simple function that finds NS records, resolves their IP, and attempts a DNS Zone Transfer
import dns.zone
import dns.resolver

ns_servers = []
def dns_zone_xfer(address):
    ns_answer = dns.resolver.query(address, 'NS')
    for server in ns_answer:
        print("[*] Found NS: {}".format(server))
        ip_answer = dns.resolver.query(server.target, 'A')
        for ip in ip_answer:
            print("[*] IP for {} is {}".format(server, ip))
            try:
                zone = dns.zone.from_xfr(dns.query.xfr(str(ip), address))
                for host in zone:
                    print("[*] Found Host: {}".format(host))
            except Exception as e:
                print("[*] NS {} refused zone transfer!".format(server))
                continue

dns_zone_xfer('megacorpone.com')

You're missing a simple instruction for requirements.txt in order to get this script running successsfuly.

pip install dnspython

I've removed the deprecated messages and optimized the code a bit to use an arg instead of hardcoded domain. Maybe you want to update your code?

#!/bin/python3

A Simple function that finds NS records, resolves their IP, and attempts a DNS Zone Transfer

import dns.zone
import dns.resolver
import argparse

parser = argparse.ArgumentParser(description='Enter domain to parse and attempt a DNS Zone Transfer')
parser.add_argument("domain")
args = parser.parse_args()
print('Domain entered: ' + args.domain)

my_resolver = dns.resolver.Resolver()

ns_servers = []
def dns_zone_xfer(address):
ns_answer = my_resolver.resolve(address, 'NS')
for server in ns_answer:
print("[] Found NS: {}".format(server))
ip_answer = my_resolver.resolve(server.target, 'A')
for ip in ip_answer:
print("[] IP for {} is {}".format(server, ip))
try:
zone = dns.zone.from_xfr(dns.query.xfr(str(ip), address))
for host in zone:
print("[] Found Host: {}".format(host))
except Exception as e:
print("[] NS {} REFUSED ZONE TRANSFER!".format(server))
continue

dns_zone_xfer(args.domain)