PowerShell/Docs/check-dns.md

## The *check-dns.ps1* Script

This PowerShell script measures and prints the DNS resolution speed by using 200 frequently used domain names.

## Parameters
```powershell
check-dns.ps1 [<CommonParameters>]

[<CommonParameters>]
    This script supports the common parameters: Verbose, Debug, ErrorAction, ErrorVariable, WarningAction, 
    WarningVariable, OutBuffer, PipelineVariable, and OutVariable.
```

## Example
```powershell
PS> ./check-dns

```

## Notes
Author: Markus Fleschutz | License: CC0

## Related Links
https://github.com/fleschutz/PowerShell

## Source Code
```powershell
<#
.SYNOPSIS
	Checks the DNS resolution 
.DESCRIPTION
	This PowerShell script measures and prints the DNS resolution speed by using 200 frequently used domain names.
.EXAMPLE
	PS> ./check-dns
.LINK
	https://github.com/fleschutz/PowerShell
.NOTES
	Author: Markus Fleschutz | License: CC0
#>
 
try {
	Write-Progress "⏳ Step 1/2 - Reading from Data/frequent-domains.csv..."
	$Table = Import-CSV "$PSScriptRoot/../Data/frequent-domains.csv"
	$NumRows = $Table.Length

	Write-Progress "⏳ Step 2/2 - Resolving $NumRows domains..."
	$StopWatch = [system.diagnostics.stopwatch]::startNew()
	if ($IsLinux) {
		foreach($Row in $Table){$nop=dig $Row.Domain +short}
	} else {
		foreach($Row in $Table){$nop=Resolve-DNSName $Row.Domain}
	}

	[float]$Elapsed = $StopWatch.Elapsed.TotalSeconds
	$Average = [math]::round($NumRows / $Elapsed, 1)

	if ($Average -gt 10.0) {
		"✅ DNS resolves $Average domains per second"
	} else {  
		"⚠️ DNS resolves only $Average domains per second!"
	}
	exit 0 # success
} catch {
	"⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])"
	exit 1
}
```

*Generated by convert-ps2md.ps1 using the comment-based help of check-dns.ps1*