#!/usr/bin/env python3

# Two ways of querying a specific nameserver.

import dns.message
import dns.rdataclass
import dns.rdatatype
import dns.query

# This way is just like nslookup/dig:

qname = dns.name.from_text('amazon.com')
q = dns.message.make_query(qname, dns.rdatatype.NS)
print('The query is:')
print(q)
print('')
r = dns.query.udp(q, '8.8.8.8')
print('The response is:')
print(r)
print('')
print('The nameservers are:')
ns_rrset = r.find_rrset(r.answer, qname, dns.rdataclass.IN, dns.rdatatype.NS)
for rr in ns_rrset:
    print(rr.target)
print('')
print('')

# A higher-level way

import dns.resolver

resolver = dns.resolver.Resolver(configure=False)
resolver.nameservers = ['8.8.8.8']
answer = resolver.resolve('amazon.com', 'NS')
print('The nameservers are:')
for rr in answer:
    print(rr.target)

# Sending a query with the all flags set to 0.  This is the easiest way
# to make a query with the RD flag off.
#
# This sends a query with RD=0 for the root SOA RRset to the IP address
# for l.root-servers.net.

q = dns.message.make_query('.', dns.rdatatype.SOA, flags=0)
r = dns.query.udp(q, '199.7.83.42')
print('\nThe flags in the response are {}'.format(dns.flags.to_text(r.flags)))
print('The SOA in the response is "{}"'.format((r.answer)[0][0]))