<# .SYNOPSIS Lists DNS servers .DESCRIPTION This PowerShell script measures the latency of public and free DNS servers and lists it. .EXAMPLE PS> ./list-dns-servers Provider IPv4 Latency -------- ---- ------- AdGuard DNS 94.140.14.14 / 94.140.15.15 222 / 205 ms ... .LINK https://github.com/fleschutz/PowerShell .NOTES Author: Markus Fleschutz | License: CC0 #> function CheckDNSServer { param($Provider, $IPv4Pri, $IPv4Sec) $SW = [system.diagnostics.stopwatch]::startNew() $null = (nslookup fleschutz.de $IPv4Pri 2>$null) [int]$Elapsed1 = $SW.Elapsed.TotalMilliseconds $SW = [system.diagnostics.stopwatch]::startNew() $null = (nslookup fleschutz.de $IPv4Sec 2>$null) [int]$Elapsed2 = $SW.Elapsed.TotalMilliseconds New-Object PSObject -Property @{ Provider=$Provider; IPv4="$IPv4Pri / $IPv4Sec"; Latency="$Elapsed1 / $Elapsed2 ms" } } function List-DNS-Servers { Write-Progress "Loading Data/public-dns-servers.csv..." $Table = Import-CSV "$PSScriptRoot/../Data/public-dns-servers.csv" Write-Progress "Measuring latency..." foreach($Row in $Table) { CheckDNSServer $Row.PROVIDER $Row.IPv4_PRI $Row.IPv4_SEC } Write-Progress -completed " " } try { List-DNS-Servers | Format-Table -property @{e='Provider';width=50},@{e='IPv4';width=32},@{e='Latency';width=15} exit 0 # success } catch { "⚠️ Error in line $($_.InvocationInfo.ScriptLineNumber): $($Error[0])" exit 1 }