The most commonly used network operating system

In this Q&A, Lindi Horton answers the question "What network operating system is more currently and commonly used?"

I have what I thought was a simple question, but I can't find a simple answer anywhere. Presently in the United States, what is the most commonly used network operating system? I read somewhere that Novell NetWare was, but then I read that it's usage/popularity waned in the 90's. What about 2006? Thanks!

As with all answers in engineering, it depends. As far as network equipment and market share, the Cisco IOS would be the most prevalent network device operating system in the United States presently. Cisco's devices currently have approximately 80% of the market share in the continental United States. If you are thinking about network applications such as DNS, DHCP, or network authentication, then you would want to look at Microsoft and their Active Directory platform as the current leader.

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