Get-DhcpLeaseInfo

Get-DhcpLeaseInfo.ps1

function Get-DhcpLeaseInfo {
    [CmdletBinding(DefaultParameterSetName='HostName')]
    param(
        [Parameter(Mandatory=$true, HelpMessage='Name of the the DHCP server being queried.')]
        [string]$ComputerName,
        [Parameter(ParameterSetName='HostName', HelpMessage='The host name property to be queried.', Mandatory=$true)]
        [string]$HostName,
        [Parameter(ParameterSetName='OUI', Mandatory=$true, 
            HelpMessage='First three octets of the mac addresses you being searched for. For example: AA-BB-CC')]
        [string]$OUI,
        [Parameter(ParameterSetName='IP', Mandatory=$true, HelpMessage='IP Address of the client being searched for.')]
        [ValidatePattern('\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}')][string]$IPAddress
    )
    switch ($PSCmdlet.ParameterSetName) {
        'HostName' {
            Get-DhcpServerv4Scope -ComputerName $ComputerName | ForEach-Object {
                Get-DhcpServerv4Lease -ComputerName $ComputerName -AllLeases -ScopeId ($_.ScopeID)
            } | Where-Object 'HostName' -Match $HostName
        }
        'OUI' {
            $regex = "^([0-9A-Fa-f]{2}[:-]){2}[0-9A-Fa-f]{2}$"
            if ($OUI -match ':') {
                $OUI = $OUI.Replace(':','-')
            }
            if ($OUI -match $regex){
                Get-DhcpServerv4Scope -ComputerName $ComputerName | ForEach-Object {
                    Get-DhcpServerv4Lease -ComputerName $ComputerName -AllLeases -ScopeId ($_.ScopeID)
                } | Where-Object 'clientid' -Match $OUI
            }
            else {
                Write-Error 'The OUI input is not an appropriately formatted mac address'
            }
        }
        'IP' {
            if ([ipaddress]$IPAddress) {
                Get-DhcpServerv4Scope -ComputerName $ComputerName | ForEach-Object {
                    Get-DhcpServerv4Lease -ComputerName $ComputerName -AllLeases -ScopeId ($_.ScopeID)
                } | Where-Object 'ipaddress' -Match $IPAddress
            }
        }
    }
}