currently I am study in Linux System Administration but I seek another field related to network and security administration, now I have a question: which of these fields is better to master: Windows Server Administration or work in CISCO-related filed such as configuring routers? please notice that I want to have a coherence and consistent mastery of network and security.
closed as off topic by Iain♦ May 1 '12 at 16:11
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If you want a 'mastery' you'll need to know a good amount about all these subjects, in fact I suggest anyone working in any of these areas to learn at least the basics about the other areas. In fact I'd go as far as to say that anyone in a sysadmin role needs to know a decent amount about power/cooling, server hardware, networking, storage, patching, Linux/Windows/ideally-both, alerting/management etc. Sure you'll naturally move towards being more specialised in one area but I've never met a sysadmin that I admired who didn't know a good chunk about all of those things.
While "networking" is a broad term... you as a system administrator should be competent and proficient in understanding the OSI model and TCP/IP in both IPv4 and IPv6. You should know how ethernet and other transports work and how IP addressing and subnetting works. Mastering these layers and concepts will put you WAY over the top of peers who are too lazy to learn these things. As someone had to GO BACK and learn much of it, let me just say that you should learn it, and learn it right, the first time.
The best way to do this? It varies from person to person, but I think everyone can benefit from having to pass the CCNA certification which does a fairly good job at weeding out those who don't know how to put effort into learning, comprehending, and practicing these skills which are essential foundations to being proficient at OTHER things.