Function Parameter Validation With Parameter Attributes

function Test-ValidIp($ipaddress)
{
    try {
        [System.Net.IPAddress]::Parse($ipaddress) | Out-Null
        return $true;
    }
    catch {
        return $false;
    }
}

function Use-IpAddress
{
    Param
    (
        [parameter(Mandatory=$true,
                    HelpMessage="Enter an IP Address")]
        [ValidateScript({Test-ValidIp $_})]
        [String]
        $IpAddress
    )

    # Work with $ipaddress here
}

# Works fine
Use-IpAddress -IpAddress "192.168.1.3"
# Prompts for IPAddress
Use-IPAddress
# Throws Error
Use-IpAddress -IpAddress "garbage"