ActiveXperts Network Monitor ships with a powerful set of pre-defined checks. Each individual check has a static number of configuration items. To monitor other items, or to combine monitoring items, you can make use of custom PowerShell checks.

Most of the built-in checks have a PowerShell equivalent, implemented as a PowerShell (.ps1) script file. Out-of-the-box, each PowerShell script monitors the same items as the built-in check. Feel free to modify the script.

To add a new PowerShell-based DNS monitoring check, do the following:

• On the 'Monitor menu', open 'New Monitoring Check (Script)' and choose 'New PowerShell Check'. The 'PowerShell Check' dialog box appears;
• In the 'Script File' selection box, select 'Dns.ps1';
• In the 'Script Parameters'group box enter the required parameters. You can also load a working sample first by clicking on the 'Click here to load a sample' link.

To customize the above monitoring check, click on the 'Edit button' next to the 'Script File' selection box. Notepad will be launched. You can now make changes to the PowerShell script.

Dns.ps1 script source code

#################################################################################
# ActiveXperts Network Monitor PowerShell script, (c) ActiveXperts Software B.V.
# For more information about ActiveXperts Network Monitor, visit the ActiveXperts 
# Network Monitor web site at https://www.activexperts.com
#################################################################################
# Script
#     DNS.ps1
# Description: 
#     Query a DNS server, and validate the response
#     This function uses the ActiveXperts Network Component, an ActiveXperts product.
#     ActiveXperts Network Component is automatically licensed when ActiveXperts 
#     Network Monitor is purchased
#     For more information about ActiveXperts Network Component, see: 
#       www.activexperts.com/network-component
# Parameters:
#     1) strDnsServer - Host name or IP address of the (remote) DNS server
#     2) strHost - Hostname or domain to query
#     3) strExpectedValue - expected value 
# Usage:
#     .\DNS.ps1 '<Hostname | IP>' 'host' '<expected value>'
# Sample:
#     .\DNS.ps1 'ns1.ascio.net' 'smpp.activexperts-labs.com' '84.53.114.73'
#################################################################################

# Parameters
param
  (
    [string]$strDnsServer,
    [string]$strHost,
    [string]$strExpectedValue
  )

cls

# Check paramters input
if ( ([string]$strDnsServer -eq "") -or 
     ([string]$strHost -eq "") -or 
     ([string]$strExpectedValue -eq "") 
   )
{
  echo "UNCERTAIN: Invalid number of parameters - Usage: .\DNS.ps1 <strDnsServer> <strHost> <strExpectedValue>"
  exit
}

# Create object
$objDnsServer = new-object -comobject ActiveXperts.DnsServer
$objConstants = new-object -comobject ActiveXperts.ASConstants


#################################################################################
# THE SCRIPT ITSELF
#################################################################################
  
$SYSDATA = ""
$bMatched = $false

# Lookup
$objDnsServer.Server = $strDnsServer
$objDnsServer.Lookup( $strHost, $objConstants.asDNS_TYPE_A )

if ( $objDnsServer.LastError -ne 0 )
{
  return "UNCERTAIN: Unable to connect to query [" + $strDnsServer + "]"
  exit
}  

$objDnsRecord = $objDnsServer.GetFirstRecord()

while ( $objDnsServer.LastError -eq 0 )
{
  if( $objDnsRecord.Name -eq $strHost ) 
  {
    if ( $SYSDATA -ne "" )
    {
      $SYSDATA = $SYSDATA + "; " 
    }  
    $SYSDATA = $SYSDATA + $objDnsRecord.Address
    if ( $objDnsRecord.Address -eq $strExpectedValue )
    {
      $bMatched = $true
    }
  }
  $objDnsRecord = $objDnsServer.GetNextRecord()
}
  
if ( $bMatched -eq $true )
{
  $res = "SUCCESS: Response matched; DATA = " + $SYSDATA
  echo $res
  exit
}  
else
{
  $res = "ERROR: Response did not match; DATA = " + $SYSDATA
  echo $res
  exit
}