What is the purpose of administrative installation initiated using msiexec /a?

Question

Windows Installer technology supports administrative installation. The command line for initiating administrative installation is: \'msiexec /a setup.msi\'.

Answer 1

In the real world, it doesn't have all that much value at all. MSI was designed back in a day when a computer typically had a 2-20gb hard drive. They came up with all these "run from source" advertisement scenarios which seemed really cool back then but never really caught on in the real world.

Today, what /a does for me, a setup developer, is give me an easy way to "extract" an MSI and verify its contents. That's about it.