Quick IP Cheat Sheet used for Reference

IP Cheat Sheet

	Hosts	Netmask	Amount of a Class C
/30	4	255.255.255.252	1/64
/29	8	255.255.255.248	1/32
/28	16	255.255.255.240	1/16
/27	32	255.255.255.224	1/8
/26	64	255.255.255.192	1/4
/25	128	255.255.255.128	1/2
/24	256	255.255.255.0	1
/23	512	255.255.254.0	2
/22	1024	255.255.252.0	4
/21	2048	255.255.248.0	8
/20	4096	255.255.240.0	16
/19	8192	255.255.224.0	32
/18	16384	255.255.192.0	64
/17	32768	255.255.128.0	128
/16	65536	255.255.0.0	256

How Computer Networking Can Benefit a Company

Technology is advancing at a rapid pace in today’s world. Businesses are constantly in high demands of technicians that understand the ebb and flow of information through technical devices and that is able to keep up with the growth and new innovations of demanding vendors. Computer networking is one of the many and perhaps most efficient way that information enters and leaves in the complex world of business.
Like any profession, computer networking is an art and science combined. A graphic designer can strike up a beautiful piece of artwork, but like any artist, whether it be a musician or the next Picasso, passionate artists can capture your emotions or attention. Most of the time, find themselves lost in the zone of their passion. This can be applied to computer networking as well, understanding how a business actually functions and fluctuates from day to day, month to month, and year to year is the first step in determining how to set up a network that is suitable for it. Through planning and drafting sketches, you can produce the best possible routing table and in the process, while keeping in mind how your vendor will use information, you can locate and weed out any possible conflicts or problems you may encounter in setting up this beautiful piece of network master piece. Combined with science and the results are unlimited, that’s why there are many more networking schemes to yet be discovered.
Like chemistry and biology, scientists are still researching on new medicines and cures for existing illnesses and diseases. For example, AIDS and HIV are one of the many researches taking place as one speaks. There are many computer scientists today, researching and developing new innovations in the lab and then test running them on current existing businesses to gain feedback and insights on the next big networking scheme. When implemented correctly, businesses can function properly with information being delivered on time, efficiently, and consistently; most definitely contributing to the success of a business and at the same time, giving them the upper hand in competition. We all know
that when things run smoothly, we can channel our focus on something else; in this case, the ROI of a business. So not only does efficient networking contribute to a business success, it allows it to direct its focus elsewhere, for example; push on sales and focus on net profit for a better return on investment and performance inclination. These are just a few major benefits businesses can gain through use of computer networking; it’s no wonder they spend millions of dollars for technology every year. Take Microsoft Sharepoint for example, last year alone, they spent over millions of dollars on innovations but made over hundreds of millions of dollars back on their returns of investments and profits. Sharepoint, a web-development platform has really proved indispensible to any business owner or business in need of a quick, professional, and functional website. About 5 years ago and the years preceding, you had to fully understand computer language, such as HTML, CSS, JavaScripts, and PHP to create a website Now, you just do it with the dragging and click of a button. Most likely, not as easy as 1, 2, 3, but it’s almost as easy as coloring a book. Although this may prove negatively on current professional designers, it has proved indispensible to businesses around the world, and that’s what new innovations ought to do; make life easier. It has also made the job a lot easier and reduced the cost of spending for website designers to most companies. One can reckon the force of how powerful technology can be, but at the same time how dangerous it could be to society.
In health and pharmaceuticals research, some corrupted scientist could invent a dose of drug that could be harmful or detrimental to society, or in the worst case scenario, wipe out the human population. Computer scientist must always be aware that an innovation of theirs could possibly be the vice versa outcome they had expected. This is where the movies and films such as iRobot and Frankenstein came about. Like all professions, good morals and values is essential to every step in research and development, let alone, life itself.
The ebb and flow of information isn’t just the presence and absence of information. It’s art and science combined, whether complex or compound, its value is crucial and vital on businesses all around the globe. For some it could mean a lot of money, but for the ones that truly have a passion in it, nothing is impossible. It’s the boundary between science and art, like the law of time, gravity, and the universe according to Albert Einstein. Time can only tell, but when solved, cracked, or broken; possibilities and new innovations are endless. For the time being though, they are just floating around, patiently waiting to yet to be discovered by a passionate artist/scientist.

Exam Essential: Internetworking

Know the possible causes of LAN traffic congestion
Too many hosts in a broadcast domain/storms, multicasting, and low bandwidth are all possible suspects of LAN traffic congestion.

Be able to distinguish the difference between a collision domain and a broadcast domain
Collision domain is an Ethernet term used to describe a network collection of devices in which one particular device sends a packet on a network segment, forcing every other device on that same segment to pay attention to it. On a broadcast domain, a set of all devices on a network segment hear all broadcasts sent on that segment.

Be able to distinguish the difference between a hub, a bridge, a switch, and a router
Hubs create one collision domain and one broadcast domain. Bridges break up collision domains but create one super duper large broadcast domain through use of hardware addresses to filter the network. Switches are really just multiple port bridges with more intelligence. They break up collision domains but create one large broadcast domain by default and also uses hardware addresses to filter the network. Routers break up broadcast domains (as well as collision domains) and use logical addressing to filter the network.

Know the OSI layers
It’s mandatory that you know the OSI layers and the function each layer provides. There are seven layers in the OSI reference model. The upper layers consist of The Application, Presentation, and Session Layers, and are responsible for communicating from a user interface to an application. The bottom layers consist of The Transport, Network, Data Link, and Physical Layers. The transport layer provides for segmentation, sequencing, and virtual circuits. The network layer provides for framing and placing of data on the network medium. Last but not least, the physical layer is responsible for taking 1s and 0s and encoding them into a digital signal for transmission on the network segment.

Remember the types of Ethernet cabling and when to use them
There are three types of cables that can be created from an Ethernet cable:

• Straight-through
• to connect a PC’s or a router’s Ethernet interface to a hub or switch.
• Crossover
• to connect hub to hub, hub to switch, switch to switch, or PC to PC.
• Rolled
• for a console connection from a PC to a router or switch

Understand how to connect a console cable from a PC to a router and commence HyperTerminal
You should know how to do this for the exam: Take a rolled cable and connect it from the COM port of the host to the console port of a router. Start HyperTerminal and set the BPS to 9600 and flow control to none.

Memorize the three layers in the Cisco three-layer model

• Core
• Distribution
• Access

Where do you take the CCNA Exams?

You can take the CCNA Composite exam at any Pearson VUE authorized testing centers or call 877-404-EXAM (3926).

Follow these steps to register for a CCNA exam:

1. Determine the number of exam you would like to take. (Composite exam number is 640-802.)
2. Register with the nearest Pearson VUE testing center. At this time, you will be asked to pay in advance for the exam. The current fee for the exam is $150.00 and must be taken within one year of the time of payment. You may also schedule exams up to six weeks in advance or as late as the day you are planning to take it on. However, if you fail a Cisco exam, you must wait five days before you are allowed to re-schedule for another shot at it. Because life can be unexpected, if something is to pop up on your test day, and you need to cancel or reschedule your exam, contact Prometric or Pearson VUE AT LEAST 24 hours in advance.
3. Upon scheduling the exam, you will receive instructions regarding all appointment and cancelation procedures, the ID requirements, and information regarding the testing-center location.

Here are some general tips for exam day:

1. Of course, arrive early at the exam location, so you’re able to relax and get a review in before the test. You should not be trying to study the information on this day.
2. Read each of the questions carefully. Be certain of what exactly each question is asking before diving in to conclusion.
3. If you’re stuck on a question, your best bet is to use the process of elimination to get rid of the obviously incorrect answers first. This can greatly improve your odds of choosing the wrong answer.
4. Because you can no longer move forward or backward through the exams, you will need to double-check your answers before proceeding to the next. Make sure you don’t forget this.
5. And last but not least, stay focused, attentive, and conscious throughout the whole exam.

The physical layer, hubs, and ethernet

The main functions of the physical layer is to send bits and receive bits, as well as state transitions.

• Bits come in only values of 1 or 0 (morse code with numerical values).
• State transitions – changes in voltage from high to low and vice-versa.

Hubs at the physical layer

What is a hub?

• A hub is really a multiple port repeater.

Hubs in a network

• All devices in the same collision domain.
• All devices in the same broadcast domain.
• Devices shares some bandwidth.

What is a Physical Star Network?

• A physical star network is where the hub is a central device and cables are extended in all directions from it.

Note: Hubs and repeaters can be used to enlarge the area covered by a single LAN segment, however, this is NOT RECOMMENDED.

Ethernet at the physical layer

• Created by a group called DIX (Digital, Intel, Xerox)
• There are three types of ethernet
  • 802.3u – Fast Ethernet
  • 802.3ab – Gigabit Ethernet on Category 5
  • 802.3ae – 10Gbps over fiber and coax

Electronics Industries Association and The Newer Telecommunications Industry Alliance (EIA/TIA)

• The standard body that creates the physical layer/specifications for ethernet.
• EIA/TIA specifies that ethernet use a registered jack (RJ) connector with a 4 5 wiring sequence on unshielded twisted pair (UTP) cabling (RJ45).

Cables

• Cables are measured in decibals (dB)
• Cabling in corporate and home markets is measured in categories.
  • A higher quality cable will have a higher rated category and lower attenuation.
    • ex. category 5 > category 3

Key term:

• Crosstalk – the unwanted signal interference from adjacent pairs in the cable.