Functions/Test-NtpDateVsNow.ps1
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Function Test-NtpDateVsNow { <# .SYNOPSIS To test whether local time and NTP time fall within a particular tolerance .DESCRIPTION To test whether local time and NTP time fall within a particular tolerance. The NTP protocol allows for an acceptable drift between local and NTP time. Will return a [Boolean] and accepts the -Verbose parameter .PARAMETER ComputerName The name or IPv4 address of the computer running NTP .PARAMETER Tolerance The acceptable number of seconds difference between local and NTP time. Default = 300. Valid range 1-3600 seconds (1 hour) .NOTES Will return a value of $False if either: a) the time difference is greater than the $Tolerance; or b) the time server does not reply to the NTP time request being sent by this function .EXAMPLE Test-NtpDateVsNow $DC Assuming $DC holds the name of the domain controller then would return the boolean $True .EXAMPLE Test-NtpDateVsNow "DoesNotExist" Assuming "DoesNotExist" doesn't actually exist as a computer name then would return the boolean $False .OUTPUTS A boolean $true or $false indicating if comparing local time to NTP time falls within a tolerance .LINK NTP - Network Time Protocol .LINK w32tm.exe .LINK http://www.pool.ntp.org/en/ #> #region Parameters [CmdletBinding(ConfirmImpact='None')] [OutputType('bool')] Param ( # Specifies the NTP server to communicate with [parameter(Mandatory, ValueFromPipeline, Position=0, HelpMessage='Enter a ComputerName or IpAddress of a system acting as a time server [domain controller] or appliance')] [Alias('NtpServer')] [string] $ComputerName, # Specifies the acceptable number of seconds difference between local and NTP time [parameter(ValueFromPipeLineByPropertyName)] [ValidateRange(1,3600)] [int] $Tolerance = 300 ) #endregion Parameters begin { Write-Verbose -Message "Starting $($MyInvocation.Mycommand)" } process { $Ntp = Get-NtpDate -ComputerName ($ComputerName) write-verbose -message "Getting NTP time from $ComputerName and time is $Ntp" $Now = Get-Date write-verbose -message "Getting local time and time is $Now" $AbsDiff = [math]::Abs(($ntp - $now).TotalSeconds) write-verbose -message "There are $AbsDiff seconds difference between times, and comparing to $Tolerance is" if ($AbsDiff -gt $Tolerance) { write-output -inputobject $false } else { write-output -inputobject $true } } end { Write-Verbose -Message "Ending $($MyInvocation.Mycommand)" } } #EndFunction Test-NtpDateVsNow |