There are 2 ways to get the Visual Studio 2015 installation for offline installation:
Option 1 – ISO File: Download the ISO file for Community or Enterprise edition. Then virtual mount them to a drive or extract them using a tool (like 7Zip), and start your installation. When I tried this option, the visual studio seemed to miss few packages which it downloaded through an online feed during the installation. So, a better option is to use…
Option 2 – /layout switch: Download the web installer for Community or Enterprise edition. Using administrative command prompt, navigate to the folder where the installation file were downloaded and run the installation file with /layout command.
Example, for Community edition it would be vs_community.exe /layout and for Enterprise version it would be vs_enterprise.exe /layout. This option allows you to download the full set of files to a local folder, and this folder has all the necessary files for offline installation.
Same way the installation for latest Windows SDK can also be prepared.