Motherboard bus
(expansion) slots
For example, if the motherboard doesn't already have a
built-in sound card, then you can add a sound card by
inserting one into one of these bus slots, which gives
your computer the ability to produce sound. Or let's say
the motherboard doesn't have enough USB ports to suit
your needs, well then you can add a USB expansion
card in one of the bus lots to add more USB ports.
A common bus type today is
called PCI, which stands for
peripheral component
interconnect. PCI has
been around since 1993 and
was a standard bus slot for
modern motherboards until
PCI-express came out,
which we'll talk about
shortly. PCI slots are much
faster when compared to the
very old ISA slots, with a PCI
data path of 32 or 64 bits,
and speeds ranging from
133 to 533 MB/s. They are
half the physical length of an ISA slot.
also about
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PCI Express is the latest
version of bus slots. It's
faster than its
predecessor, with speeds
up to 4 GB/s. Unlike
standard PCI, which
transfers data in parallel,
PCI Express transfers data
in serial. Transferring data
in serial is much faster
PCI Express than parallel because
serial data is transferred in
packets.
PCI Express was designed to succeed all other PCI bus
slots and the older AGP. However, it is not backward
compatible with standard PCI, because the architecture
is very different.
There are four different
slot sizes in PCI Express.
There is PCI Express 1,
4, 8, and 16. PCIe x1 has
one lane for data. A lane
has 4 wires. Two are for
sending, and two are for
receiving. PCIe x4 has
four lanes. PCIe x8 has
8 lanes. And the fastest PCIe x16
PCIe x8
slot is PCIe x16, which PCIe x4
has 16 lanes and has PCIe x1
also succeeded the AGP
slot for the video card.
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There is also the PCI-X
slot, where the X stands for
it extended. The PCI-X slot
is basically an extension of
the old standard PCI slot
and it's almost twice the
length. The PCI-X is a 64-
bit bus, and it's backwards
compatible with the
standard PCI slot.
PCI-X
It was mainly designed to work with servers and high-
speed computers.
There is also the mini PCI
slot and this is what is used
in laptops. It's approximately
one quarter the length of a
standard PCI slot. The mini Mini PCI slot
PCI slot is a subset of the
standard PCI bus, but it's a
lot smaller. Now you can
insert a regular PCI card into
a mini PCI slot, but you
would have to use a mini
PCI to PCI converter. The
mini PCI is a 32-bit, 33 MHz
Mini PCI card
bus.
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Mobile Issues
Phones & Laptops
You may come across some
issues when you're dealing with
mobile devices, such cell phones.
And two of the biggest cell phone
operating systems are Apple and
Android. A lot of cell phones
today are touchscreen, and one of
the common problems that you
may encounter with touchscreens
is that sometimes they are not
Touchscreen cell
responsive. You touch the
phone
screen, and nothing happens. So
when this happens, the best thing to do is to power off
the phone and then turn it back on, and a lot of times
this fixes the problem. Or if you still have the issue,
you can try and eject your
SIM card and then reinsert
it. If that doesn’t work, you
may have to do a hard
Phone SIM card reset on your cell phone.
And you can refer to the
manufacturer's documents for specifics on how to do a
hard reset for your specific device.
Sometimes you may have issues when you touch an
app and the app won't load, or you may have an
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issue with the performance of
your device and you find it to be
running very slow. A lot of this
could be caused by having too
many apps open already, and
those apps are eating up
memory and CPU resources
and slowing the performance of
the device or even freezing it.
So the first thing you should try
Phone with a lot is to kill any apps that you have
of apps open. open and see if that fixes the
issue. For example on an
Apple device, the way to kill apps, is to double click
the home button and swipe up each app that’s open,
and it will close that app.
Also with cell phones, you may encounter issues
where your GPS is not working. Certain applications
on your phone require your GPS. So if a certain app
is not working, it could be that your GPS is turned off.
So the first and most obvious
thing to do is to go into the
settings on the phone and
make sure that the GPS is
turned on. Or if your GPS is
turned on, and you're still
having issues, you have to
remember, that your GPS uses
satellites for communication.
So for example, if there's a
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cloudy day, then that could interfere with satellite
communication.
As far as troubleshooting
issues with laptops; one of
the main problems is that
sometimes when you turn on
the power, but your screen is
blank. Nothing shows up on
the screen. You may hear
the fans running, you may
see the LEDs turn on, but No display (blank
your screen is still blank. screen) on a laptop.
This is called a no display
issue. Now, this could happen for a few reasons. But
the best thing to do right from the start is if you have an
external monitor, go ahead and connect an external
monitor to your laptop and see if an image shows up on
an external monitor. Now if an image does show up on
your external monitor, then that means your LCD
monitor on your laptop is bad, and it needs to be
replaced.
Laptop connected to external monitor
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Another problem is that
when you turn on the
laptop, you see an image
that's very faint. The
display is very dim.
In this case, most likely
you would have to replace
the inverter. The inverter
Dim display is a small circuit board
that supplies power to the
LCD monitor. It converts
DC current to AC current.
The inverter is usually
Inverter mounted inside the
display panel, just below
the screen.
If you press the power button on your laptop and let's
say that nothing happens. In other words, you don't
see any power LEDs, your screen is blank, and you
don't hear any fans turning. One of the first things to
check is making sure your battery charger is plugged
into the wall and to your laptop. Once you verify that,
and still nothing happens? Well then most likely your
laptop’s motherboard is dead and needs to be
replaced.
Laptop plugged into
a wall outlet
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A flickering monitor can also be related to a bad LCD
or inverter, especially if the failure is related to
movement; in other words, if the flickering happens
when you physically move the laptop. So most likely it
is a hardware failure.
Problems with keys sticking is
another issue that can happen
with laptops. One thing you'll
notice is that laptop keyboards
are not as durable as regular
desktop keyboards. So they are
more susceptible to wear and
tear, and tend to wear out a lot faster. So if you're
going to repair a laptop keyboard or replace the
keyboard, you need to be extra careful.
Another issue on laptops, is sometimes people
complain that as their typing on the keyboard, the
mouse cursor moves all by itself. This is known as
ghost cursor.
Palms of hands or
sleeves on a shirt,
touching the
touchpad, could
cause a ghost cursor.
The main reason (especially in my personal
experience in dealing with my customers) is that when
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a person types on the laptop keyboard, a lot of times
they don't realize that the palms of their hands or the
sleeves on their shirt are touching the touchpad.
Which will move the cursor. So the best way to solve
this problem is to go into the software touchpad
settings on the laptop and disable the tap
feature. Another issue that could cause a ghost
cursor could be improper touchpad drivers. So the
best thing to do is to go to the manufacturer's website
and download the correct and latest drivers for the
touchpad.
A very common issue that
happens with laptops is
overheating. A lot of
people complain that as
they are working on their
laptop, the laptop shuts
down or freezes. Which is a
very common symptom of
overheating. Laptops have
air vents either on the side
or on the bottom of a laptop,
along with fans. And air
passes through these vents and fans to help cool the
laptop. But if these vents are blocked, for example
with dust, it will hinder the laptop’s cooling ability. So
the best way to fix this problem is to get a can of
compressed air and blow out the vents and fans and
free them from any dust or debris.
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Use a can of compressed air to free the laptop's
fans and vents from dust and debris.
But another issue that causes a laptop to overheat is
a lot of times people use their laptops, and they're not
placing them on a flat hard surface. For example,
they're using them on soft surfaces like their couch or
on their bed. When this happens, a lot of times the
vents and fans will get blocked and will hinder air
circulation, especially if the fans and vents are on the
bottom of the laptop.
Hard surface Soft surface
GOOD BAD
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You may also encounter an issue with your laptop
where the battery is not being charged. Your battery
is in the laptop and a battery charger is plugged in,
but you'll notice that there was an indicator informing
you that the battery is not charging.
Now most likely this could be a problem with the
battery itself, and it needs to be replaced. Or it could
also be a problem with the laptop's motherboard. Or
in another scenario, let's say your battery is fully
charged, but the battery only lasts a few minutes
before it discharges. Now, this is a very common
issue with older laptops. Often times when laptops
reach around 5 years old, the battery will only last a
few minutes on a full charge, for example, they may
only last about 10 minutes. And this happens
because batteries lose their capacity to hold a charge
as they get older. So all you have to do is replace the
battery for the laptop.
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All laptops have the capability of wireless networking.
And a lot of times you may have a situation where you
have an intermittent wireless connection. This could
be due to a problem where there is interference
between your laptop and your wireless router, or it
could be that you might be out of range of your
wireless router.
Out of range or interference issues could cause
intermittent wireless problems.
Another intermittent wireless issue could be that you
would need to update your wireless network card
drivers. Especially when there's a new operating
system that's been released. In fact, I have personally
found this issue to be common with the release of
Microsoft Windows 10, where a common fix for
an internment wireless issue, is to go to the laptop
manufacturer's website and update your wireless
network card drivers.
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BIOS / CMOS
BIOS stands for basic input
output system. The BIOS
is software that is built into
the motherboard that
initializes the computer’s
peripherals as the computer
is being booted. Some of
these peripherals include the
keyboard, mouse, video
card, optical drives, and so
on. After it initializes the BIOS initializing the
peripherals, it then searches computer at startup.
for a boot device, like an
optical drive, USB drive, or a hard drive, to boot software
or an operating system.
The BIOS software is stored on the BIOS chip on the
motherboard. The BIOS chip is non-volatile, which
means that the software and settings are retained even
after the power is turned off.
BIOS chip stores the BIOS
software (firmware).
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Some popular vendors of BIOS software are American
Megatrends and Phoenix Technologies.
After a computer is turned off, and if the power cable is
unplugged, the computer needs to maintain certain
settings. Such as the date, time, and hardware
settings. And these setting are stored on the
motherboard in a special chip called a CMOS chip.
CMOS stands for complementary metallic oxide
semiconductor. And in order for the CMOS chip to
maintain these settings, it needs a battery. This battery
is called the CMOS battery.
CMOS battery
The CMOS battery is a small button cell battery, which
can be seen on the surface of the motherboard. It's
usually located on the bottom right-hand corner. The
CMOS battery is basically the same type that is typically
used in wrist watches.
When you turn on a computer, the computer does
what’s called a power on self test or POST, which is
run by the BIOS. It tests the computer to make sure all
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the requirements are met and the hardware is working
correctly before continuing.
BIOS doing a POST (power on self test).
So after POST has passed, and as stated before, the
BIOS searches for something to boot from such as an
operating system, which is typically loaded on the hard
drive. But the computer doesn’t necessarily have to
boot to an operating system.
Hard drive
Optical drive
USB
FLOPPY
Boot priority screen in CMOS setup.
It can also boot from other things such as an optical
drive or a USB drive, just as long as those drives
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have the necessary boot files on them. And how the
BIOS determines which device to boot from, depends
on the boot priority in the CMOS settings. The boot
priority screen is where you can make changes in the
boot order.
So for example, If the optical drive is set as the first
boot device, then the BIOS will check that first and look
for booting software and if it doesn’t find anything, it will
move on to the 2nd device on the list and check that
next. Then it will continue down the list until it finds
something to boot from. But, you can change the boot
priority in the CMOS setup and put in any order you
choose. Then once you make the change, you just
save the settings and the next time you reboot the
computer, the settings will take effect.
The BIOS will go down the list of boot
devices, based on the order, to find a drive
that has boot software on it.
Now there are certain things you can do while you're in
the BIOS. For example, you can set the date and
time.
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The data and time should be accurate because the
operating system does reference it.
Setting the date and time in the BIOS.
Other things you can do in the BIOS, is enable or
disable certain devices. For example, if your
motherboard has a built-in video, network, or sound
card, you can disable these devices to save resources
if you're not using them. But that's only if you already
have separate adapter cards installed on the
motherboard that already gives you these capabilities.
The BIOS also allows you to modify the CPU clock
speed by either increasing the clock speed to make the
computer run faster, (which will increase the
temperature) or by reducing the clock speed which will
make the computer run slower (which will lower the
temperature). Reducing the clock speed can be
especially useful if your computer is having overheating
issues. And speaking of temperature, the BIOS can
also monitor the temperature of the CPU.
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The BIOS has a built-in safety
mechanism, that if the CPU
reaches a certain temperature
threshold, it will automatically
shut down the computer. Or if
it detects that the CPU fan is
not spinning, it will shut down
the computer to prevent
damage to the CPU from
overheating.
You can change the clock speeds in the BIOS.
But these temperature thresholds can be modified in
the BIOS if you want to, by either increasing or
decreasing the temperature threshold. And you can
also modify the fan speeds of the computer.
You can also enable or disable virtualization in the
BIOS. Virtualization is a technology that enables your
computer to run multiple operating systems in different
partitions. The operating systems are not actual, but
they are virtual. So if your computer is preventing you
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from installing or running virtualization software, it
could be that virtualization is disabled in the BIOS.
One way to protect your computer from unauthorized
users is by using password protection in the BIOS.
Using a BIOS password not only prevents changes to
the settings, but it also protects the system from
booting. A user cannot boot up the computer or make
any changes in BIOS without the password.
Password protection in the BIOS.
Another BIOS security measure is drive lock. Drive
lock prevents the hard drive from being accessed by
using password protection. When drive lock is
enabled in the BIOS, a user cannot access the drive
without the password. The password is stored on the
hard drive, but it cannot be read or removed.
Some BIOS systems have an intrusion detection
feature. This feature detects if the computer case has
been opened and alerts the user.
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ALERT! COVER HAS BEEN OPENED.
Intrusion detection system alerts you if the
computer case has been opened.
And some computers,
especially laptops, can be
equipped with LoJack, which
is a service that can locate
your computer if it has been
THIEF!
stolen.
When you turn on a computer, the computer does
what’s called a power on self test, or POST. It tests
the computer to make sure
all the requirements are met
and if the hardware is
working correctly before
starting the operating
system. If the computer
passes the test, the internal
speaker will make a short
A single beep indicates a
single beep, which indicates
successful POST
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the computer has passed the test and is booting up
normally. However, if there are no beeps or multiple
beeps, then that means
that the computer failed
the test and something is
wrong, and the computer
needs further trouble
shooting to find out what
the problem is.
Whether there are no
beeps or multiple beeps,
Multiple beeps indicates a
the computer will generate problem.
a beep code to help you
pinpoint the problem. For example, if the computer
generates 3 long beeps, then that could indicate a
keyboard error. Or if the computer generates a
continuous short beep, then that could indicate a
problem with a RAM module. Whatever BIOS is
installed on your computer’s motherboard, you can
refer to the manufacturer’s documentation to find a list
of beep codes and what they mean.
A new type of BIOS is called UEFI. UEFI stands for
unified extensible firmware interface. Now most, if
not all new motherboards, are shipped with his newer
type of BIOS. UEFI has several advantages over the
old BIOS. And the first and most obvious, just by
looking at it, is that it has a user-friendly graphical user
interface that supports different colors and even
animations. Whereas the old BIOS has your typical
blue screen that resembles the Windows blue screen of
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BIOS (OLD) UEFI (NEW)
death. UEFI can also recognize larger hard drives, and
you can even use a mouse in the UEFI interface, as
compared to the old BIOS, where mouse support was
not even available and you had to use your keyboard
only. UEFI also has a built-in feature called secure
boot. Secure boot stops any digitally unsigned drivers
from loading and it helps to stop malicious software
such as rootkits.
Larger view of a UEFI
interface
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Front Panel Connector
Typically located at the bottom right-hand corner of the
motherboard, you'll find what's called the front panel
connector. And this is where you would plug and wires
that connect to items that are in the front bezel of the
computer case. So for example, there is a power button
connector, and this turns a computer on or off. There's
also the power LED, which indicates when the computer
is on or off, or in standby mode. There is also the hard
drive LED, which indicates when there is hard drive
activity. There is also the reset switch, which restarts
the computer by doing a hard boot. And there is also a
speaker connector, which is used to plug in the internal
speaker of the computer. Often times the front panel
connector will be color-coded to help identify where the
wires connect to, which makes knowing where to
connect the wires a lot easier.
Color-coded, front panel
connector on a
motherboard.
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Most computers today will have certain common
connections on the front panel of the computer case, for
easy access. For example, you may find some USB
ports. You may also find some audio ports, one for
headphones or speakers, and another one for a
microphone. You will also find on the front panel, the
power button, which is used for turning on or off the
computer. You will also see a reset button, which is
used for doing a hard reboot. And there is also the hard
drive activity light. And when this light blinks, it means
that there is activity in the computer. In other words, the
hard drive is being accessed.
Easy access connections, and LEDs on
the front panel of the computer case.
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RAID
Storage is another very important part of fault
tolerance. If something were to happen to a company's
data, such as a disk failure that results in data loss,
then that is going to have a serious impact on how a
company performs. That's why we need to make sure
that if a disk does fail, that
no data loss will occur. So
one of the best ways to
prevent data loss is RAID.
RAID stands for redundant
array of independent
disks. In a RAID set up, the
data is copied on multiple
disks. So that in the event of
a disk failure, no data will be lost. Now there are 4
common levels of RAID. There is RAID 0, RAID 1,
RAID 5, and RAID 10.
Now RAID 0 is not fault tolerant. In fact, RAID 0
shouldn't even be called RAID, because not only does
it not provide fault tolerance, but it actually increases a
chance for data loss. Because in a RAID 0, the data is
not duplicated, but it's actually spread or striped across
two separate disks. So if just one of these disks fails,
then all the data will be lost. So the only reason why
you would want to use Raid 0, is speed. Because
when you have two disks controllers working instead of
one, then accessing data is much faster.
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Spread or
striped,
over two
disks.
DISK 1 DISK 2
RAID 0 is not fault tolerant.
It's only for speed.
Now RAID 1 is fault tolerant. In a RAID 1 setup, the
data is copied to more than one disk. So disk 2 would
have the exact same copy of the data, as disk 1. So in
the event of a single disk failure, no data loss would
happen, because the other disk has a duplicate copy.
There are also two different setups in RAID 1,
mirroring and duplexing. Mirroring is when all the
disks use the same controller. But duplexing is when
each disk has their own controller. So duplexing is
more fault tolerant of the two setups, because it would
still continue to function if a controller goes down.
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Each disk
has the
same
data.
DISK 1 DISK 2
RAID 1 - the data is copied on
more than 1 disk.
Now RAID 1 is fault tolerant. In a RAID 1 setup, the
data is copied to more than one disk. So disk 2 would
have the exact same copy of the data, as disk 1. So in
the event of a single disk failure, no data loss
would happen, because the other disk has a duplicate
copy. There are also two different setups in RAID 1,
mirroring and duplexing. Mirroring is when all the
disks use the same controller. But duplexing is when
each disk has their own controller. So duplexing is
more fault tolerant of the two setups, because it would
still continue to function if a controller goes down.
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Next, we'll talk about RAID 5. In order to use RAID 5,
you need to have 3 or more disks. RAID 5 is probably
the most common setup that is used, because it's fast
and it can store a large amount of data. In a RAID 5
setup, the data is not duplicated, but it's striped or
spread across multiple disks. And in addition to the
data, there was another very important piece of
information that is being evenly spread across all the
disks. This information is called parity. And parity is
used to rebuild the data in the event of a disk failure.
But there is a downside to RAID 5, because since the
equivalent of an entire disk is used to store parity, it
reduces the collective amount of data that can be
stored in this array. So for example, if all four of these
disks (see graphic below) were 1 TB each, then that
totals 4 TB. But in a RAID 5 setup, the total amount
that would be used for data storage would be 3 TB,
because the equivalent of 1 entire disk (1 TB) would be
used to store parity.
DISK 1 DISK 2 DISK 3 DISK 4
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RAID 5 - the data is spread or striped across
multiple disks. In addition to parity.
Finally, there is RAID 10. RAID 10 is basically what
the name says. It's combining RAID 1 and RAID 0
together, and you need to use a minimum of four disks.
So in a RAID 10 setup, a set of 2 disks are mirrored
using a RAID 1 setup. Then both sets of the two disks
are striped using RAID 0. So RAID 10 benefits from
the fault tolerance of RAID 1, and the speed of RAID 0.
But the downside in a RAID 10, is that you can only
use 50% of the capacity for data storage. So if you are
using 4 disks in a RAID 10 setup, you can only use two
of them for actual storage.
DISK 1 DISK 2 DISK 3 DISK 4
RAID 10 - combines RAID 1 & RAID 0. In RAID 10, a set of
2 disks are mirrored using RAID 1. Then both sets of the
2 disks are striped using RAID 0.
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Networking Cables
& Connectors
This is the RJ-11 connector. RJ
stands for registered jack. This is
a 4 wire connector, used mainly to
connect telephone equipment. But
as far as networking, the RJ-11 is
used to connect computers to local
area networks through the RJ-11
computer's modem. The RJ-11
locks itself and to place by a single locking tab, and it
resembles an RJ-45, but it's a little bit smaller.
Now the RJ-45 is by far the
most common network
connector. This is an 8 wire
connector, used to connect
computers to local area
networks. And like the RJ-
11, it also locks itself into
RJ-45 place by a single locking
tab, and it also resembles
or RJ-11, but it's a little bit
larger.
The BNC connector is a common type of RF connector
that is used on coaxial cable. BNC stands for bayonet
128
neill concelman. And the
BNC is used for both analog
and digital video
transmissions, as well as
audio.
BNC
This connector is called the F-
type. Now, this is a threaded
connector, typically used on
coaxial cables. These are
primarily used by cable
providers to attach to cable
F-type modems. The F-type hand
tightens by an attached nut.
This is the IEEE 1394
connector, and this is also
known as firewire. Firewire
is recognized by its D shape.
This type of connection is
becoming less popular on
desktops and laptops. It's Firewire
commonly associated with
attaching peripheral devices
such as digital cameras and printers, rather than being
used as network connections.
This is the USB connector. The USB is very common
on desktops and laptops. Just about every kind of
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peripheral connects to a computer, using the USB
connector. There are also several different types of
USB connectors. There is the type A, type B, the mini
USB, and the micro USB.
TYPE A TYPE B MINI MICRO
A newer type of interface for attaching external
peripherals is called Thunderbolt. Thunderbolt is a
high-speed technology
interface that outputs one
serial signal from a
combination of PCI express
and the DisplayPort.
Thunderbolt was released in Thunderbolt
2011, and was mainly used in
Apple products. And now it has become available to
PCs. There are three different versions of
Thunderbolt. Versions 1 and 2, use the same
connector as the mini DisplayPort. And version 3,
uses a USB type C connector.
Version 1 & 2 Version 3
Another type of connector is called RCA. The RCA is
an older type connector that was produced in the
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1940s. These were
primarily used to carry
video and audio signals. A
lot of times you may see
RCA connectors in a group
of 3, a yellow, a white, and
a red. The white and red
are used for audio, such as
a left and right speaker. RCA connectors
And the yellow would be
used for video.
Our next connector is
called the LC or local
connector. And this is a
fiber optic connector. It
uses a jack similar to the
RJ-45. This type of
LC connector is commonly
used between floors in a
building.
This fiber optic connector
is called the ST or straight
tip. This uses a half-twist
bayonet type of lock and is
commonly used with single ST
mode fiber optic cable.
Our last fiber optic connector is called the SC or
standard connector. And this uses a push-pull
connector similar to audio and video plugs. And like
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the LC connector, this is also commonly used
between floors in a building.
SC
The term plenum refers to a space in a building where
there is open airflow circulation. And this is usually
between the drop ceiling and the structural ceiling.
Buildings that don't have plenum spaces have air ducts
encapsulating the airflow. So as a result, buildings that
have plenum spaces, where there is adequate open
airflow, are more prone to fires than buildings that don't
have plenum spaces.
Plenum Non Plenum
Open air flow (dangerous) Encapsulated air flow (safer)
And because of this, cables that run through plenum
spaces must meet certain requirements. First, they
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must be more fire-resistant. And secondly, they must
not produce any toxic fumes if they are burned.
Sometimes there might be cases in your home or office,
where you wanted a certain computer in a certain part of
the building, to be able to access the internet or to be
networked. And for whatever reason, network cabling
or Wi-Fi just wasn't an option in that part of the building.
Maybe because of difficulties in the structure of the
building, interference, or whatever. So a new
technology gave the ability to network using the existing
electrical system of the building. Ethernet over
powerline gives the ability of Ethernet networking over
power.
Powerline
network adapter
So, for example, let's say you needed a computer to be
able to access the internet. But for some reason, you
can't get any network cables or any Wi-Fi signal to
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reach that computer. So, in this case, we're going to
use Ethernet over power. So we're going to need a
couple of powerline adapters. These powerline
adapters plug directly into a power outlet and they have
a built-in Ethernet port for an RJ-45 connector.
Computer plugged into a powerline
network adapter.
So one adapter plugs into a power outlet next to the
computer that you want to have internet access
(above). Then you would connect a network cable from
the adapter to the computer. Then the other adapter
plugs into the power outlet next to the modem or router
(below) and then connected with a network cable.
Modem plugged into a
powerline network adapter.
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So now Ethernet data will use the building's electrical
wiring to deliver networking data to the other
powerline adapter so that the computer can access
the internet.
Another standard is called
Ethernet over HDMI. The
HDMI 1.4 specification adds
another channel to an HDMI
cable for data, which will
have the capability of
Wiring Standards
network communication. So
the connected devices that HDMI cable
use this feature will have the
ability to send and receive data at 100 Mb/s Ethernet.
So, in addition to video and audio on a single cable, the
HDMI cable will have another ability of Ethernet
networking.
The terms 568A and 568B, refer to a set of wiring
standards developed by TIA / EIA, which is also known
as the Telecommunications
Industry Association. And
these terms define the
rules on how twisted pair
cables should be wired to
RJ-45 connectors.
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The 568A standard is wired in this order: White/green,
then green, white/orange, blue, white/blue, orange,
white/brown, and brown.
White - Green
Green
White - Orange
Blue
White - Blue
Orange
White - Brown
Brown
568A wiring standard
And the 568B standard is wired in the following order:
white/orange, then orange, white/green, blue,
white/blue, green, white/brown, and brown.
White - Orange
Orange
White - Green
Blue
White - Blue
Green
White - Brown
Brown
568B wiring standard
There is no difference in the functionality as to which
standard is used.
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Whether you choose to use the A or B wiring standard,
if both ends of the cable are wired using the same
standard, then this is known as a straight cable. For
example, this cable is wired on both ends using the
568A standard.
Straight cable
A straight cable allows signals to pass straight through
from end to end. This is the most common type of
cable and it's used to connect computers to hubs,
switches, or modems.
Another type of cable is called a crossover. A
crossover cable is created when both ends of the cable
are wired using the two different standards. For
example, one end is wired using the A standard, and
the other end is wired it using the B standard.
Crossover cable
Crossover cables are used to connect two similar
devices together. For example, you can use a
137
crossover cable to connect two computers directly to
each other without using a hub or switch. They are also
used to connect hubs or switches to each other.
A rollover cable is created when both ends are wired
completely opposite of each other. These are used to
connect a computer or a terminal, to a router’s console
port.
Both ends are wired
completely opposite
from each other.
Rollover cable
A loopback cable is used for testing purposes. It’s to
make a computer think that it's connected to a network.
To make a loopback cable, you connect pin 1 to pin 3
and pin 2 to pin 6.
Loopback cable
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Firewalls
A firewall can be either software or hardware. It's a
system that is designed to prevent unauthorized access
from entering a private network, by filtering the
information that comes in from the internet. It blocks
unwanted traffic and permits wanted traffic. So
basically it filters the incoming network data packets
and determines by its access rules if it is allowed to
enter the network. In today's high tech world, a firewall
is essential to every business to keep their network
safe.
Firewall in a private network.
Firewalls come in different types. One type is called a
host-based firewall. A host-based firewall is a
software firewall. This is the kind of firewall that is
installed on a computer and it protects that computer
only and nothing else. For example, later versions of
Microsoft operating systems come pre-packaged with a
host-based firewall. You can turn a host-based firewall
on or off, and you can also create exceptions to the
139
firewall based on the application name on the
exceptions tab (see below). And of course, you can
always purchase a third-party firewall and install it on
your computer.
Media Types
Host-based Firewall on Exceptions tab on a host-
Microsoft Windows. based firewall.
Today there are several different categories of twisted
pair cables that you're going to need to know for the
exam. The difference between these is the maximum
speed that can handle without having any crosstalk
(interference). The numbers of these categories
represent the tightness of the twists that are applied to
the wires. And you can see an illustration below of the
categories and speeds of different twisted pair cables.
140
CATEGORY SPEED
10 Mbps
100 Mbps
1,000 Mbps e = enhanced
1,000 Mbps 10,000 Mbps (cable
length under 100 meters)
10,000 Mbps a = augmented
10,000 Mbps Added shielding to the
wires.
Unshielded twisted pair (UTP) is by far the most
common type of table that is used today. It consists of
4 pairs of unshielded wires twisted around each other.
The wires are twisted to prevent electromagnetic
interference or crosstalk. This type of cabling is mainly
used on local area networks.
Unshielded twisted pair (UTP) cable
Now shielded twisted pair (STP) is very similar to
unshielded twisted pair, except that it has a foil shield
141
that covers the wires. This shielding adds a layer of
protection against electromagnetic interference,
leaking into and out of a cable.
Shielded twisted pair (STP) cable adds a
foil shield that covers the wires.
This is a coaxial cable. This
is used today primarily by
cable providers to provide a
computer with broadband
internet connection. Early on
it was used as a backbone
for networks, such as a bus
Coaxial cable
network. There are also
two common types of
coaxial cable. The first type is RG-6. RG-6 is made for
long distances and is commonly used for cable
television and internet connection. The second type is
RG-59, and this is made for short distances and is
commonly used for high definition and high quality
video.
Now we're getting into fiber optic cables. Below, are
cutaway views of fiber optic cables and a light source.
Fiber optic cable uses pulses of light to send data, and
as a result, it is very fast and it can span for great
distances.
142
Now there were two different modes in fiber optics:
Single-mode fiber and multi-mode fiber. Single-mode
fiber is a fiber optic cable that allows light to enter only at
a single angle. So when this type of transmission of light
enters at this angle, it can span for long distances.
Single-mode fiber - Light enters at a single
angle. Made for long distances.
Below is multi-mode fiber. The difference between
multi-mode and single-mode, is that in multi-mode, light
travels in multiple beams that reflect off the walls of the
cable. And unlike single-mode fiber, multi-mode fiber is
made for short distances.
Multi-mode fiber - Light reflects off the walls of
the cable. Made for short distances.
143
Network
Components
Those of you who have
broadband cable internet will
recognize this device. And yes,
this is your typical DOCSIS
cable modem. DOCSIS stands
for data over cable service
interface specifications. The
DOCSIS 3.1 specification
supports speeds of 10 gigabit
downstream and 1 gigabit
upstream. The DOCSIS modem
handles both incoming and
Cable modem
outgoing data signals, including
internet, video, and voice.
A hub is a device that has
multiple ports that accepts
Ethernet connections from
network devices. A hub is
considered not to be
intelligent because it does
not filter any data or has any Hub
intelligence as to where
data is supposed to be sent. When a data packet
144
arrives at one of the ports, it is copied to all other ports,
so all the devices on that hub sees that data packet.
So this not only creates security concerns, but it also
creates unnecessary traffic on the network.
Now a switch is very similar to a hub. It's also a device
that has multiple ports that accepts Ethernet
connections from network devices. But unlike a hub, a
switch is intelligent. A switch can actually learn the
physical addresses of the
devices that are connected
to it, and it stores these
addresses in a table. So
when a data packet is sent
to a switch, it’s directed
only to the intended
Switch destination port. That's the
major difference between
a hub and a switch. So
as a result, switches are far more preferred over hubs,
because they reduce any unnecessary traffic on the
network.
A bridge is used to divide a network into separate
collision domains. For example, if you have a network
that is segmented into two by a couple of hubs, then all
the broadcast traffic from the two segments are seen by
all the computers. And this causes unnecessary traffic.
So that is where a bridge can be helpful. If you add a
bridge to this network, it will reduce any unnecessary
145
traffic between the two segments by filtering the data
based on their MAC address. The bridge only allows
data to crossover if it meets the required MAC address
of the destination, because a bridge keeps a record of
all the MAC addresses of the NICs that are connected
to it. And it will also block all data from crossing over if
it fails to meet this requirement.
Bridge
Segment 1 Segment 2
Bridges reduce unnecessary traffic on a network by
allowing or blocking data based on their MAC address.
A segment is part of a network that is separated
from the rest of the network by a device, such as a
hub, switch, bridge, or router.
Now a router does exactly what its name implies. A
router is a device that routes or forwards data from one
network to another based on their IP address. When a
data packet is received from the router, the router
inspects the packet and determines if the packet was
meant for its own network or if it's meant for another
146
network. If the router determines that the data packet
is meant for its own network, it receives it. But if it's
not meant for its own network, it sends it off to another
network. So a router is essentially the gateway for
network.
Router
Networking devices need electrical power to function,
and that's why they have a separate power cable. But
some networking devices don't have a power cable.
It’s not that they don't need electrical power, it's just
that they get their power and data from the same
cable, which is through the Ethernet cable. And this
technology is known as PoE, which stands for power
over Ethernet.
Here is a switch and a hub that receive power from
the network Ethernet cable, instead of a separate
power cable.
147
A wireless access point is basically a wireless hub
that is used by wireless devices. It connects to a wired
network and relays data between the wired network
and the wireless device for communication purposes.
In the illustration below, you see a wireless access
point that's wired to a network so that the wireless
laptop can communicate with the network.
Wireless access
point (WAP)
A network interface card or NIC, is used to connect a
computer to a network. It is basically a circuit board
with a network adapter that is installed on your
computer. Its job is to convert
incoming serial data into parallel
data, so that the computer can
understand it. A NIC provides a
constant dedicated connection to a
network. And every NIC has its
own unique identifier, called a NIC
MAC address.
148
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