clarifying public clients

Tweaking this line to make sure customers understand that PUBLIC clients and PUBLIC DNS needs to be able to resolve the hostname you setup and expose to public clients that would then connect through some public network device, usually a gateway service, to access web app running on private network.

Author: toddfoust

articles/azure-monitor/app/availability-private-test.md

@@ -15,7 +15,7 @@ If you want to use availability tests on internal servers that run behind a fire
 > [!NOTE]
 > If you don't want to allow any ingress to your environment, use the method in the [Disconnected or no ingress scenarios](#disconnected-or-no-ingress-scenarios) section.
 
- Ensure you have a public DNS record for your internal website. The test will fail if the DNS can't be resolved. For more information, see [Create a custom domain name for internal application](../../cloud-services/cloud-services-custom-domain-name-portal.md#add-an-a-record-for-your-custom-domain).
+ Ensure you have a public DNS record for your internal website. The test will fail if the target url hostname cannot be resolved by public clients using public DNS. For more information, see [Create a custom domain name for internal application](../../cloud-services/cloud-services-custom-domain-name-portal.md#add-an-a-record-for-your-custom-domain).
 
 Configure your firewall to permit incoming requests from our service.