Periodic DNS resolving test

Test-Dns.ps1

function Test-DnsResolving($DnsServer, $Delay, $Query)
{
    begin { 
        $testsCount = 0
        $latencySum = 0
        $max = [Double]0
        $min = [Double]99999
        [Console]::TreatControlCAsInput = $true
    }

    process {
        while($true) { 
            if([Console]::KeyAvailable) {
                $key = [Console]::ReadKey($true)
                if ($key.Key -eq "C" -and $key.Modifiers -eq "Control") {
                    break
                }
            }

            $resolverResponse = $null
            $time = (Measure-Command { $resolverResponse = Resolve-DnsName $Query -Server $DnsServer -DnsOnly }).Milliseconds
            
            $records = $resolverResponse.Count

            if($time -gt $max)
            {
                $max  = $time
            }
            if($time -lt $min)
            {
                $min = $time
            }
            $latencySum += $time
            $testsCount += 1

            ("{0}: {1} ms ({2} records returned)" -f (Get-Date), $time, $records)
            
            Start-Sleep -Seconds $Delay 
        }

    }

    end {
        [Console]::TreatControlCAsInput = $true

        ""
        "{0} tests executed" -f $testsCount
        "Minimum = {0}ms, Maximum = {1}ms, Average = {2}ms" -f $min, $max, [Math]::Round(([Double]$latencySum / $testsCount))
        ""
    }
}

# Get connected adapter
$adapter = Get-NetAdapter | Where-Object Status -EQ Up | Select -First 1

# Get adapter's DNS servers
$servers = (Get-DnsClientServerAddress -InterfaceIndex $adapter.InterfaceIndex -AddressFamily IPv4) | Select-Object -ExpandProperty ServerAddresses

# Use first DNS server and run test (test can be cancelled by CTRL-C)
Test-DnsResolving -DnsServer $servers[0] -Delay 3 -Query "outlook.com"