Time DNS requests

dnstest.py

#!/usr/bin/env python
from __future__ import print_function
from __future__ import unicode_literals

import socket
import sys
import threading
import time

if len(sys.argv) != 2:
    print('Usage: dnstest.py HOSTNAME', file=sys.stderr)
    sys.exit(1)

hostname = sys.argv[1]
try:
    socket.gethostbyname(hostname)
except Exception as e:
    print('Failed to look up hostname {hostname}: {err}'.format(hostname=hostname, err=unicode(e)), file=sys.stderr)
    sys.exit(1)

def do_test():
    start = time.time()
    addr = socket.gethostbyname(hostname)
    end = time.time()
    delay = end - start
    ts = time.strftime('%H:%M:%S', time.localtime(start)) + '.{0:03d}'.format(int((start-int(start)) * 1000))
    logline = '{ts} {delay:.5f}\n'.format(ts=ts, delay=delay)
    sys.stdout.write(logline)
    sys.stdout.flush()

while True:
    t = threading.Thread(target=do_test)
    t.daemon = True
    t.start()
    time.sleep(0.1)