4.1 KiB
DNS Diagnostics and Performance Measurement Tools
Ever been wondering if your ISP is hijacking your DNS traffic? Ever observed any misbehavior with your DNS responses? Ever been redirected to wrong address and suspected something is wrong with your DNS? Here we have a set of tools to perform basic audits on your DNS requests and responses to make sure your DNS is working as you expect.
You can measure the response time of any given DNS server for arbitrary
requests using dnsping. Just like traditional ping utility, it gives you
similar functionality for DNS requests.
You can also trace the path your DNS request takes to destination to make sure
it is not being redirected or hijacked. This can be done by comparing different
DNS queries being sent to the same DNS server using dnstraceroute and observe
if there is any difference between the path.
dnseval evaluates multiple DNS resolvers and helps you choose the best DNS
server for your network. While it is highly recommended to use your own DNS
resolver and never trust any third-party DNS server, but in case you need to
choose the best DNS forwarder for your network, dnseval lets you compare
different DNS servers from performance (latency) and reliability (loss) point
of view.
prerequisites
This script requires python3 as well as latest
dnspython. Please note that "dnstraceroute"
requires a modified version of dnspython module, which is included. You just
need to run git submodule update --init
dnsping
dnsping pings a DNS resolver by sending an arbitrary DNS query for given number of times:
% ./dnsping.py -c 3 -s 8.8.8.8 -t MX wikipedia.org
DNSPING 8.8.8.8: hostname=wikipedia.org rdatatype=MX
101 bytes from 8.8.8.8: seq=0 time=161.607 ms
101 bytes from 8.8.8.8: seq=1 time=156.355 ms
101 bytes from 8.8.8.8: seq=2 time=145.201 ms
--- 8.8.8.8 dnsping statistics ---
3 requests transmitted, 3 responses received, 0% lost
min=145.201 ms, avg=154.388 ms, max=161.607 ms, stddev=8.378 ms
This script calculates minimum, maximum and average response time as well as jitter (stddev)
dnstraceroute
dnstraceroute is a traceroute utility to figure out the path that your DNS request is passing through to get to its destination. You may want to compare it to your actual network traceroute and make sure your DNS traffic is not routed to any unwanted path.
% ./dnstraceroute.py -s 4.2.2.1 yahoo.com
dnstraceroute.py 4.2.2.1: hostname=yahoo.com rdatatype=A
1 192.168.199.57 (192.168.199.57) 47 ms
2 192.168.198.21 (192.168.198.21) 21 ms
3 192.168.169.169 (192.168.169.169) 27 ms
4 192.168.168.137 (192.168.168.137) 28 ms
5 so-5-0-0.franco71.fra.seabone.net (89.221.34.6) 23 ms
6 xe-5-3-1.fra44.ip4.gtt.net (89.149.129.185) 62 ms
7 * 1126 ms
8 ae-1-60.edge5.Frankfurt1.Level3.net (4.69.154.9) 62 ms
9 ae-1-60.edge5.Frankfurt1.Level3.net (4.69.154.9) 12 ms
10 a.resolvers.level3.net (4.2.2.1) 171 ms
dnseval
dnseval is a bulk ping utility that sends an arbitrary DNS query to a give list of DNS servers. This script is meant for comparing response time of multiple DNS servers at once:
% ./dnseval.py wikipedia.org
server avg(ms) min(ms) max(ms) stddev(ms) lost(%)
--------------------------------------------------------------------------
4.2.2.1 151.067 131.270 221.742 28.643 %10
4.2.2.2 142.175 132.921 178.133 13.348 %0
64.6.64.6 133.047 109.145 162.938 20.609 %0
64.6.65.6 377.270 97.669 661.471 172.717 %0
8.8.4.4 389.048 294.581 511.134 67.953 %0
8.8.8.8 0.000 0.000 0.000 0.000 %100
208.67.222.222 179.068 135.975 258.582 50.681 %0
208.67.220.220 137.817 135.822 140.113 1.504 %0
Credits
- @rthalley for invaluable dnspython library
- @JustinAzoff for python-cymruwhois library
- @bortzmeyer for his feedback and patches