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Binary: The KEYS to the KINGDOM! (Part 2)

Posted in Cisco Certification with tags , , , , , , , , , , , , , , , , , , , on March 23, 2011 by jjrinehart

And now back to our regularly scheduled program, already in progress…

Getting back into the groove regarding binary, the key is associating it with our more-familiar decimal system of math.  I will frankly admit that it took me from second through eighth grade to master my times tables completely, but the 10’s were easy…you just added a zero to get the result!  The whole powers of ten (1, 10, 100, 1000) was pretty simple, 10 to the first power was 10, 10 to the second power was 100, and so on.  If you want to represent the decimal number 1,200,20,000, you can map it out to the powers of ten like this:

107 106 105 104 103 102 101 100

10,000,000   1,000,000  100,000   10,000   1,000  100   10   1

0                  1                 2                1           0         0       0     0

Simple, right?  You multiply the 1 by 1,000,000 (106) place, multiply the 2 by 100,000 (giving you 200,000) and the 1 by 10,000 (104 place), and it all adds up.  Binary works the same way, but instead of powers of 10, you use powers of two, 20, 21, etc.  The math is simple, the first place is always 1, then 2 is next, followed by 2×2 (4), 2x2x2 (8), 2x2x2x2 (16), 2x2x2x2x2 (32), 2x2x2x2x2 (64), and finally 2x2x2x2x2x2x2 (128).  Another way to think of is is that the numbers double in every “place.”  Now, let’s map the number 192 in binary, using the same format as before:

27 26 25 24 23 22 21 20

128      64      32       16       8          4          2          1

1           1           0        0        0         0         0         0

By looking at the numbers and doing a little math you can see that 128+64=192, so by placing a one in the 128 column (107) and the 64 column (106) and zeroes everywhere else, you get the binary number 1100000.  You can get decimal from binary by just doing the reverse, and multiplying 1 by 128 and 1 by 64 and adding them together.

This may seem a little strange when you first try to wrap you head around it, but it truly does explain how everything else in networking operates. My own favorite personal example is my “aha moment” regarding Routing Information Protocol.  Ever wonder why RIP has a 15 hop limit?  Simple–it has a FOUR BIT METRIC (binary 0000 through 1111); when you map the 1111 into the power of two diagram you realize that 1111 (8+4+2+1) is 15.  The protocol simply cannot count any higher!  Hopefully that gives you a small sample of why binary really is the secret decoder ring to certification and computing understanding.

– Joe

Binary: The KEYS to the KINGDOM! (Part 1)

Posted in Cisco Certification with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on March 18, 2011 by jjrinehart

Sounds corny, right, the idea of a single magic bullet or secret trick to the CCNA/NP certification?  It would be, except that it actually IS!  One of the many things I did wrong as I studied was not having a solid understanding of binary math.  As human beings, we see through the lenses of decimal—“Base 10”–probably because that’s the number of  digits (thumbs and fingers) that we use to count on.  In the world of computer technology, however, decimal means almost nothing, unless you count the forced translations we see that mask the underlying process.  All computing devices, whether workstations, servers, routers, switches, or firewalls, think in terms of two’s–simply because a circuit can only be on or off.  Once you learn to think in binary terms, just about everything else in computing actually makes perfect sense, including IP addressing, subnetting, routing protocols, and even applications.  The key to mastering something new and unfamiliar is to compare it to something you know well, and in numbering systems that would be decimal.  I have to frankly admit that I do not consider math to be my strongest subject, so if I can make sense of tis, everyone else should easily grasp it.  In my next post, I will walk through the logic, and that should make understanding this topic musch easier.

My Cisco Certification Journey

Posted in Cisco Certification with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on March 15, 2011 by jjrinehart

I started in the world of Cisco networking in 1998 after a ten year career as an ordained minister.  My first job was at a regional Internet Service Provider as a sales rep, and to be honest, I knew almost nothing about the inner workings of the technology.  To get up to speed, I went to the library and checked out Novell’s Internet Plumbing Handbook.  Unfortunately, most of it was way over my head, was a little discouraging at first, so I read it again…and again…until it started sinking in.  Initially, I had no intention of going the engineering route; I just didn’t want to be a “talking head” or “sales drone” that didn’t have a clue as to how the technology worked.  The funny thing is that once you have the “secret decoder ring,” it’s pretty cool knowing how all the pieces of networking technology fit together.  With my appetite for knowledge growing, I decided to start studying for the Cisco Certified Network Associate (CCNA) certification (this was in early 2000), and passed the exam shortly after.  For me, that was the beginning of my certification journey, culminating in achieving the CCIE in December of 2004.  All of my work in that regard began as self-funded (it took me five times to pass), and I learned a ton along the way.  Since becoming the president of the Seattle Cisco Users Group (, I have discovered a passion for teaching, allowing me to assist others in making the same journey as I have.  I look forward to passing some of the experience through my blog, which will hopefully be useful to those that read it.