This script checks whether a namesserver is active by checking a single domain against it.
dns_online_test.php [DOMAIN] [NAMESERVER]
Parameters
Note: When no parameters are used, the parameters will be imported from the config.ini.
dns_online_test.php
Checks all the domain against the nameserver specified inside the config.ini
check_certificates.php example.de ns.example.com
Checks whether the domain 'example.de' can be sucessfully looked up using the nameserver 'ns.example.com'.
Side note: We usually use the config.ini and trigger this script once a week through a crontab entry.
# DNS Online Check
0 0 * * 1-5 <path to dns_online_test.php>