Visual FoxPro

Use Public DNS Servers (Google and Cloudfare)

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Demonstrates how to use Google and Cloudfare nameservers for all DNS lookups within Chilkat.

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

Visual FoxPro

LOCAL loDns
LOCAL lnSupportsTls

* The new Chilkat DNS class is a singleton that allows an applicaton to select 
* the DNS nameservers used throughout Chilkat.

* "singleton" means that all Chilkat DNS object instances work with a single
* copy of internal DNS settings that are application wide.

* Chilkat does DNS lookups internally whenever a domain name is passed to a Chilkat method, or when the domain
* name is part of a URL passed to a Chilkat method.  It could be in HTTP, Ftp2, SSH, IMAP, Socket, etc.

* This exampel will show how to use the Cloudfare and Google DNS servers.
* 
* Google Public DNS:
*   - Primary DNS: 8.8.8.8
*   - Secondary DNS: 8.8.4.4
*   Google Public DNS is known for its speed and reliability. It's operated by Google and is widely used by many internet users.

* Cloudfare Public DNS:
*   - Primary DNS: 1.1.1.1
*   - Secondary DNS: 1.0.0.1
*   Cloudfare Public DNS is also known for its speed and reliability, and is also widely used.

loDns = CreateObject('Chilkat.Dns')

* Indicate our TLS preference:
* 0: No TLS
* 1: Prefer TLS if possible
* 2: Require TLS
loDns.TlsPref = 0

* If you choose "No TLS", then all DNS requests will use UDP, or TCP for those requests with large responses.
* Choosing "No TLS" provides the fastest DNS lookups, and is generally what you're already doing.

* If you choose "Prefer TLS if possible", then Chilkat will use DNS over TLS for those nameservers that
* support TLS.

* If you choose "Require TLS", then Chilkat will ignore nameservers that don't support TLS,
* and all DNS communications will occur over private and secure TLS connections.

* When you specify a nameserver to be used, you'll tell Chilkat whether it supports DNS or not.
* Here' we're setting the nameservers to Google and Cloudfare.
* They both support TLS, but since we set our TLS preference = 0, Chilkat will not use TLS.
* (If we set our TLS preference equal to 1 or 2, then Chilkat will use TLS for Google and Cloudfare DNS.)

* First, make sure we remove all existing nameservers.
loDns.RemoveAllNameservers()

* Add the Google and Cloudfare nameservers.
lnSupportsTls = 1
loDns.AddNameserver("1.1.1.1",lnSupportsTls)
loDns.AddNameserver("8.8.8.8",lnSupportsTls)
loDns.AddNameserver("1.0.0.1",lnSupportsTls)
loDns.AddNameserver("8.8.4.4",lnSupportsTls)

* That's it.  Now all DNS lookups in Chilkat will use the above nameservers.

RELEASE loDns