Monday, March 1, 2021

Studying for the Cisco CCNA Certification - (What is a Network?)

I am super excited to announce that I am studying for the Cisco CCNA 200-301 certification.  It has been at least a year since I passed by Network+ certification.  Now that things seem to be going back to some normalcy because my son's school is open and my daughter is back in daycare I am done taking a break from my studies and excited to learn about Cisco's entry level certification.

There are a few reasons why I want this but before I do I just wanted to provide you with my perspective on this journey.  What I will do is provide you with information I have learned and utilize the Cisco exam topics as a guide.   See below for an overview look of the Cisco CCNA exam topics.  

CCNA Exam Topics

1.0 Network Fundamentals 20%
2.0 Network Access 20%
3.0 Connectivity 25%
4.0 IP Services
5.0 Security Fundamentals 15%
6.0 Automation and Programmability 10%

Why am looking to take the CCNA exam and why am I posting what I learned on this page?  The honest truth is that after taking the CompTIA Network+ certification I knew I wanted to continue my studies in networking.  I had three different certifications I wanted to work on and the Cisco CCNA won. I wanted work on CCNA, Security+ or Linux+ but I wanted to concentrate more on networking.  

Now getting the certification is nice but I also want to get experience.  A goal of mine is to gain an opportunity as a Network Technician or Network Administrator.  Getting a certification is not the solution to this.  I must work hard to build relationships and connections with people in the network support community.

I am always looking at jobs postings to see what qualifications other network support positions "requirements".  And from what I have seen most "require" at least two to four years of hands on experience.  I think that is reasonable because after learning a bit about networking the network support manager and company cannot just trust a new person to support an entire university of switches and routers.  

Another reason why I am posting this is to keep myself accountable and to help others learn more about networking and information technology.  As most know that YouTube provides a great amount of options to watch and learn.  It is easy to watch a video about someone talking about networking but truth is we need a variety of learning options.  Hey, they helped me pass by Network+ certification.  Thank you Network Chuck, Professor Messer & Mike Meyers for the motivation and content you create each and every day. But I want to provide you simple and clean understanding of networking from my perspective, a computer support technician and by doing so I also work on reviewing the content I learned.

Think of it like when you read a chapter and at the end of the chapter you close the book and write down what you learned. This will help me in that regards.  That is what I did for my Network+ certification exam.  After each chapter or important subject I closed the book and tried to write down what I learned. This is going to be that kind of journey.  

Now on to what I learned on so far. 

First I would recommend buying a book to follow along. One of the books that I am using is the Official Cert Guide CCNA 200-201 Volume 1 by Wendell Odom.  Now I am not paid by them nor from Amazon but I included the link in this post.  Personally I am using OReilly books online, which is a first, since the Cisco press books are pretty heavy to carry around.  Plus my company uses OReilly and can get the book for free online.  If not I would have purchased the book personally and I still may buy the book because I prefer the hard book cover.  

Part 1: Intro to Networking

What is a network?

    A network is like communicating in a conversation or when two people are playing tennis. There are certain rules that computers and networks follow. There are protocols and in networking there are different network models on how a network is built. 

In the example from playing tennis.  Each player has a tennis racket but only one ball and of course the tennis court.  Let us pretend that the tennis racket is the computer and the tennis ball is an email or webpage.  Player 1 uses the tennis racket (computer) to request a webpage from lets say this website or  Once we hit enter on our computers is like player 1 hitting the ball to the other person.  

The tennis ball passes over the net, get it? No?  Okay...corny IT joke...then bounces on the ground and player 2 is ready to hit the ball to bounce it back to player 1 and hits the ball back.  Player 2 is the webpage or destination requested.  In other words it is just another computer or server.  

Whenever we make a requests from our mobile phone, tablet or computer we are just connecting from one computer to another one.  We press enter or go and the website comes back, like the tennis ball.  Continuously this happens within milliseconds and thus how we are able to get data super fast.  

Now how does this all work?  Think about how our home internet is setup.  Some of us have internet at home with our preferred network provide like Comcast, Frontier, AT&T etc.  We have two all in one devices that are the Wi-Fi, router and switch all in one. 

What I have home is not an all in one setup like the Netgear you see here or the ones you probably get from your home internet provider.  Below is like what a large office might have setup where there is a router that connects to the internet world and a switch that manages the multiple computers within that office.  In all these things are a much bigger scale and much larger devices to manager large amounts of traffic and computers at once.  As you can see from our router and wifi I can only connect up to 4 computers at once via ethernet cable.  In a business they could be double or 10 times that. 

Home Modem (Router) Only

 Home Wi-Fi (Switch) Only

Now that we have the equipment set lets go on to how things get delivered and what models are there to determine the blueprint of a network. 

First how are messages or requests delivered.  First we have an IP address.  An IP address is similar to your home address. In order for us to know where to go we would need to know the specific mailing address and the GPS (router and switch) will provide us directions on how to get there the fastest. 

An example of an IP address is all numeric for example. or or

These numbers are attached to each and every computer inside your home or business.  Now I will not go into the whole world of IP addresses because that will be for another post but just for simple sake just know that each computer has an IP address and the router and switches know how to direct that traffic in and outside of the home or office. 

Now one thing I must mention is that a HUB and a SWITCH are two totally different devices.  A hub does not have any brain but a switch does.  A hub just repeats signals and information.  For example, if you had a hub setup in your home instead of the switch (see home wifi switch picture above) any time I would send an email to one person on my network it will send it to every device connected to that hub.  This is how it was long ago and of course that does not work well when working with confidential information.  Now we have switches which are pretty much computers that control the traffic to know where to tell it to go.

Routers on the other had make packet forwarding decisions.  For example if I had to send a letter to my wife who is in the house I dont need to go to the post office to have it delivered back to my house.  I would just go to her and give her the letter.  In some ways this is how a routers and switch work within the network.  It recognizes where things go and deliver them based on the IP address and locations.

How are IP addresses saved and stored? 

There is something called a MAC address.  (media access controller address)  This a unique identifier assigned the a network interface controller (NIC) that is built into ones computer, phone and/or tablet.  Every device has its own MAC address.  For example, if you have the network cable plugged directly into the modem/router in your home and you look behind your PC you may be able to see some lights blinking where the cable is connected.  That is the network interface card.  Now for Wi-Fi they have the same things and so do our phones.  For both Wi-Fi and also for their provider like Verizon, T-Mobile or AT&T.  

To search for what your IP address and MAC address are in your Windows computer go to the Command Prompt and type ipconfig /all

The example below is what results in that command prompt.  Can you locate the MAC and IP address? 

Ethernet adapter Ethernet:

   Connection-specific DNS Suffix  . : 
   Description . . . . . . . . . . . : Intel(R) Ethernet Connection (6) I219-V
   Physical Address. . . . . . . . . : 00-1A-22-33-44-B5
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : (Preferred)
   IPv4 Address. . . . . . . . . . . : (Preferred)
   Subnet Mask . . . . . . . . . . . :
   Lease Obtained. . . . . . . . . . : 
   Lease Expires . . . . . . . . . . : 
   Default Gateway . . . . . . . . . :
   DHCP Server . . . . . . . . . . . : 
   DHCPv6 IAID . . . . . . . . . . . :
   DHCPv6 Client DUID. . . . . . . . : 
   DNS Servers . . . . . . . . . . . : 
   Primary WINS Server . . . . . . . : 
   Secondary WINS Server . . . . . . : 
   NetBIOS over Tcpip. . . . . . . . : Disabled

On a Apple computer its a bit different but can locate them by going to System Preferences > Network > Wifi or Ethernet (depending which one you have connected) > Advanced > TCP/IP. 

There you will see the IPv4 Address and information.  To find the MAC address click on the Hardware tab.  Sometimes it may just show up on the previous page where you can see the Wi-Fi and other networks.  

See pictures below to help.  These are just examples I pulled from online but you can also type ifconfig in the terminal window to see how it shows up there. 

Well I hope this information has helped so far.  Next I will post about different network models and layers of the network.  

I may note that it is important to get information as I am doing directly from the source.  Remember that I am not an expert in networking and would always recommend you work on doing your own studies and not use this as the only content needed to study for any network exam.  Most of what I am posting here is me reviewing what I learned so far about networking. 

If you have any questions or comments please leave them below.