(Visual FoxPro) Revert to Default DNS Nameservers

See more DNS Examples

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.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loDns
LOCAL lnNsCount
LOCAL i
LOCAL lnSupportsTls

* 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.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Dns')
loDns = CreateObject('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.
loDns.AddDefaultNameservers()

* Let's examine our nameservers
lnNsCount = loDns.NumNameservers
i = 0
DO WHILE i < lnNsCount
    ? STR(i + 1) + ": " + loDns.GetNameserver(i)
    i = i + 1
ENDDO

* 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
lnSupportsTls = 1
* Cloudfare
loDns.AddNameserver("1.1.1.1",lnSupportsTls)
* Google
loDns.AddNameserver("8.8.8.8",lnSupportsTls)

* See the nameservers now used by Chilkat
lnNsCount = loDns.NumNameservers
i = 0
DO WHILE i < lnNsCount
    ? STR(i + 1) + ": " + loDns.GetNameserver(i)
    i = i + 1
ENDDO

* 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.
loDns.RemoveAllNameservers()
loDns.AddDefaultNameservers()

* See the nameservers now used by Chilkat
lnNsCount = loDns.NumNameservers
i = 0
DO WHILE i < lnNsCount
    ? STR(i + 1) + ": " + loDns.GetNameserver(i)
    i = i + 1
ENDDO

* Result:
* 1: 172.16.16.16

RELEASE loDns