DnsSimpleBench is a shell script that performs a basic DNS benchmark. It is not intended to compete with existing sophisticated tools. It is intended to provide a quick check. If you wish to perform extensive DNS performance checks look at the more sophisticated tools.
The script assumes that you run the script in the directory that holds the script and the configuration files.
You may have to increase the width of your terminal to ensure that the output is displayed clearly.
Here is an example run (NOTE - the output presented below is wide).
$ ./DnsCheck.sh
-----------------+-----------------+-----------------+-----------------+-----------------+
Domain |LOCAL |CloudFlare |Google |Quad 9 |
-----------------+-----------------+-----------------+-----------------+-----------------+
google.com |0 msec |16 msec |16 msec |16 msec |
amazon.com |0 msec |12 msec |20 msec |16 msec |
nominet.uk |0 msec |16 msec |36 msec |12 msec |
reddit.com |0 msec |12 msec |20 msec |16 msec |
www.welt.de |0 msec |20 msec |20 msec |16 msec |
bbc.co.uk |24 msec |72 msec |20 msec |12 msec |
qors49ci.j |36 msec |16 msec |16 msec |12 msec |
-----------------+-----------------+-----------------+-----------------+-----------------+
$
Clone this repository into a directory on your system.
Change to the directory that holds your repo clone. Ensure that the shell script is executable. Run the shell script.
There are three components of the tool:
- the Bash shell script
DnsSimpleBench.sh - the JSON configuration file
dns_servers.jsondefines the DNS servers that are to be tested - the plain text configuration file
domains.txtdefines the DNS domains that are to be queried.
The shell script reads the 2 configuration files, it iterates over the test
domains, querying the domain, extracting the time required to perform the query
using dig against each of the DNS defined in the JSON configuration file.
The script creates an additional domain name from random characters. This is used to test performance of domains are not in the DNS server's cache.
The script does not require elevated privileges.
The requires that the toolsdig and jq are installed.
The script uses a Bash associative array as well as a standard array. The script therefore requires Bash version 4.4 or higher.
This script has been tested on Ubuntu 22.04 and Alma 9.1 with the required tools installed. This script has only been tested with the Bash shell.
The user can change both the DNS servers and test domains. If you have a large number of DNS servers you should ensure that your terminal window is wide enough to display the output clearly.
The testing of this script has been limited to 6 domains and DNS. It should be possible to use greater numbers of both, but when Bash limits are encountered the script will fail ungracefully.
The script was only tested with DNS servers with IPv4 addresses. The ISP I use does not support IPv6.
This script has only been tested with DNS services with "ASCII" names.
If you run this script more than once, all the target domains will have been loaded into the DNS servers' cache.
This script has been "linted" with ShellCheck v0.8.0. No errors or warnings were reported.
The file `dns_servers.json`` is set of key-value pairs in JSON format with the name of the DNS service as the key and primary IPv4 address of the service as the value.
# Example:
{
"Google": "8.8.8.8",
"CloudFlare": "1.1.1.1"
}
If the output has a single column for the local DNS, it is likely there is a syntax error in this file.
An example of a larger DNS server configuration file is also provided
in the repository LARGE_dns_servers.json.
The file domains.txt is plain text file that defines the set of existing
domains that the script will use. This file contains a list of domains,
one per line:
google.com
amazon.com
reddit.com
www.welt.de