While some companies elect to standardize on a single operating system across their entire network, larger enterprise companies' IT environments consist of heterogeneous equipment from a variety of manufacturers and running different operating systems. The most common of these are Linux and Windows. As a qualified Network Consulting engineer, you should be familiar with both of these operating systems and be able to manage equipment on the network that runs them. You can state a preference for one or the other if you're confident that the company also has the same preference.
