The reason makes me to ask this question is I have several Macs in my own office. Internet cost is really expensive in Australia. Moreover, it takes a lot of time if upgrading Mac OS X automatically from Apple server on each device. Is there solution to upgrade Mac OS X Yosemite via using DMG files?
Of course we do.
Go here: https://support.apple.com/downloads/ and download the Upgrade pack.DMG. But, be noticed to check your current OS X version and clarify how many particular upgrade packs you need to collect for the combo. For example, you might need to download and install more than one DMG pack when upgrading your Mac from 10.10.1 to 10.10.5
Furthermore, you are able to see the System Requirements at the bottom of each pack page.