(C) 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.

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#include <C_CkDns.h>

void ChilkatSample(void)
    {
    HCkDns dns;
    BOOL supportsTls;

    // 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.

    dns = CkDns_Create();

    // Indicate our TLS preference:
    // 0: No TLS
    // 1: Prefer TLS if possible
    // 2: Require TLS
    CkDns_putTlsPref(dns,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.
    CkDns_RemoveAllNameservers(dns);

    // Add the Google and Cloudfare nameservers.
    supportsTls = TRUE;
    CkDns_AddNameserver(dns,"1.1.1.1",supportsTls);
    CkDns_AddNameserver(dns,"8.8.8.8",supportsTls);
    CkDns_AddNameserver(dns,"1.0.0.1",supportsTls);
    CkDns_AddNameserver(dns,"8.8.4.4",supportsTls);

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


    CkDns_Dispose(dns);

    }