I setup win2008R2 Application server on Azure VM and setup Azure VPN for local address 10.0.0.0/24 and  VNET? for 10.0.1.0/24 and default gateway 10.0.1.0/25 though I do not get exact meaning of this  network settings.

By default VM OS IP setting, it get IP address through DHCP.

1

If I make Azure VPN, it is assigned the specified range automatically ? ( in this case, 10.0.1.0/24 ).

2

If I do not use Azure VPN, which range of address is assigned as internal IP to Azure VM through DHCP ?

3

If I set fixed IP address in that VM from OS setting , it will survive and IP address is not assigned by DHCP both using  Azure VPN case and not using Azure VPN case after OS reboot from OS and from Azure Portal ?

10.0.0.0/24 has an available IP address range from 10.0.0.4 to 10.0.0.254. Notice 10.0.1.x are not within this range. Further, you should not manipulate the network settings within an Azure VM. The network setting are defined via vnet setting or an associated cloud service.

When creating an Azure vnet, if you do not specify a DNS, Azure will configure the name resolution for the vnet. If you deploy a VM without specifying a vnet, Azure will manage the network setting and name resolution on your behalf.

You may find the following articles helpful:

http://aka.ms/AzureIaaSMethod

http://aka.ms/AzureVnetIP