Cannot reach apps inside a App Service Environment

Question

I am currently working on an internal application deployment, we don't want to have public internet access and we are managing all inside a Virtual Network. Inside the Virtual network we got a subnet for the ASE.

We deployed an Internal App Service Environment V3. Inside the ASE, I got a i1v2 app service plan which host a single sample application provided by Azure. The issue is that when I try to browse into the site, it returns a 'This site can’t be reached', even when I try from a VM inside the VNET.

Answer 1

Just to highlight, after your app integrates with your virtual network, it uses the same DNS server that your virtual network is configured with. If no custom DNS is specified, it uses Azure default DNS and any private zones linked to the virtual network.

Kindly check, adding the following app settings helps:

WEBSITE_DNS_SERVER with value 168.63.129.16
WEBSITE_VNET_ROUTE_ALL with value 1

These settings will send all of your outbound calls from your app into your Vnet in addition to enabling your app to use Azure DNS private zones.

#azure-dns-private-zones -“The feature can't be used by Isolated plan apps that are in an App Service Environment."

Also, after your app integrates with your virtual network, it uses the same DNS server that your virtual network is configured with.
If no custom DNS is specified, it uses Azure default DNS and any private zones linked to the virtual network.

Kindly see this doc DNS configuration for more info.

Please let us know, I'll follow-up with you further.