Python script which illustrates a timeout quering a specific nameserver for the NS records of a domain

dnspython-timeout.py

#!/usr/bin/env python
'''
Github issue opened by me: https://github.com/rthalley/dnspython/issues/45

This module is an example which creates an dns.exception.Timeout Exception on
line 43 while tpcdump shows that an answer is returned each loop in 
/usr/lib/python2.7/dist-packages/dns/resolver.py

"tcpdump -nS host 194.0.1.19 -A" from this script:
10:02:43.870020 IP 10.0.3.250.56714 > 194.0.1.19.53: 47557+ NS? server.eu. (27)
E..7..@.@.i.
..........5.#.Q.............server.eu.....
10:02:44.037592 IP 194.0.1.19.53 > 10.0.3.250.56714: 47557- 0/3/4 (179)
E.....@.8.q.....
....5....x?.............server.eu.............Q....ns1..........Q....ns2..........Q....ns.coredns.org..'......Q...M_...'......Q...*..x. .....r.....9......Q...Uw...9......Q...*..`............


"tcpdump -nS host 194.0.1.19 -A" from the dig command:
10:04:33.541576 IP 10.0.3.250.41266 > 194.0.1.19.53: 34813+ NS? server.eu. (27)
E..7.f..@..C
........2.5.#Gr.............server.eu.....
10:04:33.707040 IP 194.0.1.19.53 > 10.0.3.250.41266: 34813- 0/3/4 (179)
E.....@.7.r.....
....5.2..._.............server.eu.............Q....ns1..........Q....ns2..........Q....ns.coredns.org..'......Q...M_...'......Q...*..x. .....r.....9......Q...Uw...9......Q...*..`............


'''
import dns.resolver

if __name__ == '__main__':
    # Get the nameservers for our TLD
    tldnameservers = dns.resolver.query('eu', 'NS')
    
    # Walk trough the nameservers for our TLD
    for tldnameserver in tldnameservers:
        theNameserver = tldnameserver.to_text()
        print "going for %s" % theNameserver

        resolver = dns.resolver.Resolver()
        resolver.nameservers = [theNameserver]

        # Print the dig-like command
        print "dig -4 ns server.eu @%s" % (theNameserver)
        # Fire DNS query
        tldNameserverRecords = resolver.query('server.eu', 'NS')
        
        # Walk trough our results
        for tldNameserverRecord in tldNameserverRecords:
            print "Result: %s" % tldNameserverRecord