Tech Talk by Roland Schorr & Tower

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Let's Talk DNS

By popular request I thought I'd give a quick overview of how DNS works since it's been in the news a bunch lately. In the interests of time/space there will be a few oversimplifications here but if you're a network engineer you should already know this stuff. This little primer is intended to help the novice understand the basics of what, how and why DNS does what it does. So let's get started....

Devices on a network (or a collection of networks, like the Internet) generally use TCP/IP as the protocol they communicate with. Each device gets a unique "IP address", vaguely like the postal address on your home or office. A TCP/IP version 4 address (which is what the vast majority of the Internet is still using, for the moment) would look something like 207.155.63.6.  Four numbers, each between 1 and 254 separated by dots. There are some numbers in there that are reserved and 0 and 255 have special functions, but you get the idea.

In the beginning there were two machines on the precursor to the Internet and addresses weren't really an issue. Then there were three machines and people started to realize that typing in "207.155.63.6" was a minor pain and trying to remember it (especially when there got to be hundreds, never mind millions, of devices connected) would be a major pain.

So they figured out a way to assign friendly names to these numbers that humans could remember and type and the computers would just look up the friendly name to find out what the IP address is. That was done initially with static text files called "HOSTS" files. In fact your computer probably STILL has a HOSTS file though it's not usually used for much these days. The HOSTS files lists the names and addresses much like a phone book lists names and phone numbers.

EServer                172.23.1.4
FileServer            172.23.1.5
PrintServer         172.23.1.6
JoePC                   172.23.2.50

And so forth. This was deployed to the handful of machines on the early "Net" so that people could use English machine names and there was much rejoicing! Until the network grew to hundreds of machines and new machines (and different addresses) were being added daily (Hourly!). Then the guy in charge of updating the HOSTS file and distributing the HOSTS file and keeping track of who had what version of the HOSTS file wasn't so happy.

So a new service was invented called DNS (Domain Name System). Basically it does what the HOSTS file does but it does it in a far more automated and easy-to-maintain fashion with a database maintained, distributed and updated somewhat more automatically. With a little tweaking it scaled nicely and once again there was much rejoicing!  In fact it's what we still use today.

When you type "http://www.google.com" into your web browser your computer, behind the scenes, connects to whatever DNS server(s) it's been configured to refer to and asks what the IP address for that address is.  (173.194.79.106, if you're wondering, though in actuality they have a LOT of addresses for scale)

Every device connecting to the Internet has been set to connect to one or more DNS servers to do address lookups. This is true of a lot more than just web browsing, by the way. It's DNS that tells your e-mail server how to resolve @rolandschorr.com when you try to send an e-mail message to me. There are LOTS of DNS servers out there - in fact many if not most companies even have their own.

Fun trick: You don't NEED the friendly names if you happen to know the IP address of the server you want to go to. Type http://173.194.79.106 into your browser and your browser will very happily open Google for you. (In fact, it may open very slightly faster because it doesn't have to look up that address in the DNS first).

Maybe next week we'll explain this topic in a bit more detail...or do a totally different topic!

Word Trick of the Week

I probably shouldn't call it the "Trick of the Week" because that implies there will be another one next week.  Well, there might be.  Anyhow..

Ever open a long document you were working on and find yourself having to do a lot of paging up and down to find the spot where you left off? No need for that. Open the document and press SHIFT+F5 and Word will take you back to the last spot you were editing. This also works if you're in the document and you've scrolled (intentionally or accidentally) up or down in the document and you want to go back to where you were working. It doesn't, however, work very well in Word 2007. A bug in Word broke the feature in that version, though the clever Word MVPs have a workaround for you here.

Where's YOUR Taskbar?

As monitors get wider users sometimes find that they're more likely to have free space on the left or right than at the top or bottom. For myself I found that the nature of the way items on the Windows Task bar display meant that they were much wider than they were tall. Either way it's a possible reason to move your taskbar from the bottom of the screen to one of the sides.   Didn't know you could do that? You can! Just grab an empty part of the taskbar and drag/drop it to the side of the screen (or top of the screen) where you want it. It will happily snap into place. I dock mine on the left side of my right-hand monitor - which means it's roughly in the middle of my two monitors, easy to see and not a far mouse-throw from whereever I am.

If it doesn't move for you...right-click the taskbar and make sure you don't have it locked. You'll need to unlock it, then move it. Then you can re-lock it if you like.

You can reach Ben M. Schorr at bens@rolandschorr.com or by phone at 928-526-3970. You can follow him on Twitter @Bschorr