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. If left blank uses the Get-ADDomainController command to find domain controller which runs NTP. Aliased to 'CN', 'Server', 'NtpServer' .PARAMETER Tolerance The acceptable number of seconds difference between local and NTP time. Default = 300. Valid range 1-3600 seconds (1 hour) .PARAMETER IncludeInput Switch indicating whether to include the input parameters in the output .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 .EXAMPLE Test-NtpDateVsNow -ComputerName server01 -IncludeInput Example result LocalDate NTPDate Tolerance Difference Result NTPServer --------- ------- --------- ---------- ------ --------- 2/23/2021 2:18:02 PM 2/23/2021 2:18:02 PM 300 0.4763647 True server01 .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(ValueFromPipeline, Position = 0, HelpMessage = 'Enter a ComputerName or IpAddress of a system acting as a time server [domain controller] or appliance')] [Alias('NtpServer', 'CN', 'Server')] [string] $ComputerName = (Get-ADDomainController).HostName, # Specifies the acceptable number of seconds difference between local and NTP time [parameter(ValueFromPipeLineByPropertyName)] [ValidateRange(1, 3600)] [int] $Tolerance = 300, [switch] $IncludeInput ) #endregion Parameters begin { Write-Verbose -Message "Starting [$($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) { $ReturnVal = $false } else { $ReturnVal = $true } if ($IncludeInput) { New-Object -TypeName psobject -Property ([ordered] @{ LocalDate = $Now NTPDate = $Ntp Tolerance = $Tolerance Difference = $AbsDiff Result = $ReturnVal NTPServer = $ComputerName }) } else { Write-Output -InputObject $ReturnVal } } end { Write-Verbose -Message "Ending [$($MyInvocation.Mycommand)]" } } |