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Revert to Default DNS Nameservers

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Demonstrates how to revert back to the default nameservers of the local system where your application is running.

Note: This example requires Chilkat v9.5.0.96 or later.

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; The only reason you would have to revert back to the local system's default nameservers
; is if your application had previously set different nameservers, and you wish to revert back.

; When your application starts, the DNS nameservers to be used are the default nameservers
; configured on the system where your application is running.

; There is one exception: Chilkat defaults to using the public Google nameservers (8.8.8.8 and 8.8.4.4) for
; Android applications. Reverting to the default nameservers would revert to the Google nameservers.

; However, Chilkat does not query the local system for the default nameservers unless Chilkat needs
; to do a DNS lookup and there not yet any DNS nameservers defined.  Thus technically, when your application
; starts, there are no default nameservers. They are auto-assigned when first needed.

; If your application explicitly defines DNS nameservers, such as by calling AddDefaultnamervers, or AddNameserver
; then Chilkat will not automatically auto-assign.

$oDns = ObjCreate("Chilkat.Dns")

; Here we are explicitly adding the system default nameservers, because technically this application
; has not yet done anything that would require a DNS lookup, and thus DNS nameservers are not yet defined.
; Your default nameserver is assumed to not support TLS.
$oDns.AddDefaultNameservers 

; Let's examine our nameservers
Local $iNsCount = $oDns.NumNameservers
Local $i = 0
While $i < $iNsCount
    ConsoleWrite(($i + 1) & ": " & $oDns.GetNameserver($i) & @CRLF)
    $i = $i + 1
Wend

; On my Windows system, the result is a single nameserver at 
; 1: 172.16.16.16

; ---------------------------------------------------------
; We could add additional nameservers, such as Google and Cloudfare
Local $bSupportsTls = True
; Cloudfare
$oDns.AddNameserver "1.1.1.1",$bSupportsTls
; Google
$oDns.AddNameserver "8.8.8.8",$bSupportsTls

; See the nameservers now used by Chilkat
$iNsCount = $oDns.NumNameservers
$i = 0
While $i < $iNsCount
    ConsoleWrite(($i + 1) & ": " & $oDns.GetNameserver($i) & @CRLF)
    $i = $i + 1
Wend

; Result:
; 1: 172.16.16.16
; 2: 1.1.1.1
; 3: 8.8.8.8

; ---------------------------------------------------------
; To revert back to the system default nameservers, clear all
; then re-add the default.
$oDns.RemoveAllNameservers 
$oDns.AddDefaultNameservers 

; See the nameservers now used by Chilkat
$iNsCount = $oDns.NumNameservers
$i = 0
While $i < $iNsCount
    ConsoleWrite(($i + 1) & ": " & $oDns.GetNameserver($i) & @CRLF)
    $i = $i + 1
Wend

; Result:
; 1: 172.16.16.16