Checks whether the IP address of the given server has changed since the last time this script was called

ResolveServerAddress.psm1

<#
.SYNOPSIS
    Checks whether the IP address of the given server has changed since the last time this script was called
#>
Function Resolve-ServerAddress
{
    Param
    (
        [Parameter(Mandatory=$true, Position=0)]
        [string]
        $Server,

        [Parameter()]
        [string]
        $RegistryKey = 'HKCU:\Software\Scripts\Resolve-ServerAddress'
    )

    Begin
    {
        $regKeyPath = "$RegistryKey\$Server"

        If (-not (Test-Path $regKeyPath))
        {
            $key = New-Item $regKeyPath -Force | Out-Null
        }
    }

    Process
    {
        try
        {
            $ipAddress = [System.Net.Dns]::GetHostAddresses($Server).IPAddressToString
        }
        catch
        {
            throw "Error retrieving IP address for $Server`: $Error"
        }

        $lastIpAddress = (Get-ItemProperty $regKeyPath).IPAddress
        $lastCheckedAt = (Get-ItemProperty $regKeyPath).LastCheckedAt

        New-ItemProperty $regKeyPath -Name 'LastRun' -Value "$((Get-Date).ToString('yyyy-MM-dd HH:mm:ss'))" -Force | Out-Null
        New-ItemProperty $regKeyPath -Name 'IPAddress' -Value $ipAddress -Force | Out-Null

        if ($ipAddress -ne $lastIpAddress)
        {
            New-ItemProperty $regKeyPath -Name 'LastIPAddress' -Value $lastIpAddress -Force | Out-Null
        }

        return [PSCustomObject] @{
            Server = $Server;
            LastRun = $lastCheckedAt;
            LastIpAddress = $lastIpAddress;
            IpAddress = $ipAddress;
            ChangedSinceLastCheck = ($ipAddress -ne $lastIpAddress)
        }
    }
}