Please see IsInSubnet()
Code:

$ip='10.10.10.1'              
$networkid='10.10.10.0'              
$subnetmask='255.255.255.0'              
$answer = isinsubnet($ip,$networkid,$subnetmask)              
? 'Error = '+@ERROR+ ' - '+@SERROR              
? 'IsInSubnet = '+$answer              
redim $networkid[2]              
$ip='10.10.10.1'              
$networkid[0]='10.10.10.0/24'              
$networkid[1]='10.10.10.0/27'              
$networkid[2]='10.10.0.0/255.255.0.0'              
$answer = isinsubnet($ip,$networkid)              
$answer = isinsubnet($ip,$networkid,,1)              
$answer = isinsubnet($ip,$networkid,,2)
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There are two types of vessels, submarines and targets.