About 16 years ago I built my first DNS server. Actually, it was 2 servers as DNS is one of those things that you really need to be working all the time. Up until that time I'd been using an old-school true-Unix machine that someone else had setup and I merely maintained. So, I took 2 old Intel-based boxes (Pentium I's if I remember correctly), loaded copies of Linux Redhat on them, and then started reading Cricket's book on DNS and Bind.
If you've never had a reason to get up close and personal with DNS I highly reccommend that you do. Buy Cricket Liu's book mentioned above, read it, and then setup a server or two in your lab or at home. A comprehensive understanding of DNS is a highly valuable skill for anyone in the IT infrastructure side of things and especially for anyone on the network engineering or system administration side of the house. As you all know, application performance is sort of the "dead cat" of the IT management industry. The app guys blame the systems guys, the systems guys blame the network guys, and the network guys blame the app guys - and round and round we go. While all of this is happenign and we're looking at bandwidth congestion, system bottlenecks, and application settings - it could just be that DNS is the culprit.
If you've never resolved an application performance problem to be DNS related then you've either been really lucky or you've been solving the symptoms and not the illness. In even small organizations DNS can sometimes get really complicated. There's a great tool in our Engineer's Toolset called the DNS Analyzer that will give you a graphical representation of an organization's DNS layout. Download it and run your domain thru there. Then run a few of the larger ones and compare the results from Google.com with Suzuki.com and you'll see what I mean.
Long story short, this is one of those technologies that to be considered a senior level technologist in this space you need to be intimately familiar with. No, it may not always be top of mind but if you've got the knowledge in your head somewhere you can usually get to it when you need it...
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