Course Transcript

CompTIA A+ 220-901: Networking

Networking Basics
1. Course Introduction

2. Fiber Cable

3. Cable Characteristics Twisted Pair

4. Coaxial Cable

5. TCP/IP Protocol

6. TCP and UDP Ports

7. TCP/IP Protocol Support

8. TCP vs. UDP

9. Networking Tools

10. Wi-Fi Standards 802.11

11. Wi-Fi Encryption Types

Practice: Networking Tools

1. Exercise: Applying Networking Tools
Course Introduction
Learning Objective
After completing this topic, you should be able to
start the course

1.
[Topic title: CompTIA A+ 220-901: Networking. Your host for this video, is Michelle Plumb.] Well it’s great to work on our local PC. We may want
to share information with others either in our buildings that we working in our home environments. So we are going to take a look at networking
technologies in this section.
Fiber Cable
Learning Objective
After completing this topic, you should be able to
compare fiber cable characteristics and connectors

1.
[Topic title: Fiber Cable. Your host for this session is Michelle Plumb.] When it comes to data transmission, the need for speed is always what we
look for. And nothing is faster at this point in time than the speed of light. So fiber cables play a huge role, especially in the backbone
environment of our networks. You may see things like your cable company is using them. They've set down fiber rings to transmit that high
speed data. And it is literally plastic-ish, or glass threads that are used to actually transmit the data. And because we use the speed of light to
transfer this information, that data rate transfer is extremely high compared to its copper counter-point, right? Because if you had copper cable
you could only transmit at the speed that that metallic wire is capable of. Now there's different types of connectors. There's the standard
connector. [Or SC connector.] This is a subscriber connector, it's kind of a push-pull latching mechanism, almost like you see on your audio and
video cables. And again, used for high-speed, bi-directional transmission. And there's two fiber cables and two SC connectors that create a dual
SC connection. So depending upon the types of connections you're making, that's going to dictate the type of connectors you're using. And the
lucent connector, or sometimes called little connector, local connector [Or LC connector. ] is another type of, it almost looks like an ethernet-type
connector. Because it has a plastic pin that you push down and you shove it into the connection. Now one of the problems we have with fiber is
it's not as easy to terminate. I was actually trained many years ago in how to put a connector on a fiber cable and it's not a simple as crimping
our J45 connector onto a copper cable. And you have to test it, there's a special spectrum analyzer that tests to make sure that the cable is
hooked up properly so you get the right transmission speeds. So when it comes to these various connector types, you also have to have the
appropriate, really, connecting devices to use to actually add those ends on. So typically we purchase these fiber cables completed, right? We
don't make our own, typically. And the straight tip connector is another type of connector that we see. [Or ST connector.] And when we look at
these straight tip connectors it's kind of like a bayonet now connection. So when we talk about the different connector types again with a fiber
connector, there's a lot of different types of plugs and sockets that are used to connect these optical fibers. And in this case, we're using a
threaded, bayonet, push-pull and snap-lock type connections. And the first fiber optic connectors to be standardized were the SC, ST and FC
connectors. And, you know, typically when we go out in the field, when we use these fiber connectors, we need to make sure that whatever we're
plugging into, you know, matches up. So those are some of the things you need to be aware of when you're purchasing fiber cables. You also
have to be careful of bending that cable. Because it is a fiber, I mean light bends, it does bend in the cable, but they're easy to break. So you
can't like bend it completely in half and expect that cable to still perform properly. So you have to be careful when you're actually stringing and
laying fiber cable as well, that you don't bend it at a certain degree to actually break the fibers inside or to actually kink off. It's almost like a hose.
If you had a hose with water in it and you bent it in such a way that it kinked, then no water is transmitting through. Well you have that same
issue with fiber cable. If you kink it to that degree, then no light will be able to transmit around that bend and through the other end of the cable.
Cable Characteristics Twisted Pair
Learning Objective
After completing this topic, you should be able to
distinguish twisted pair cable and connectors

1.
[Topic title: Cable Characteristics Twisted Pair. Your host for this session is Michelle Plumb.] Ultimately, everything has to be cabled. And we use
a lot of twisted pair cabling in our work environment and even in our home environments. If you have PCs that are hardwired, servers and
routers and switches and things all use Ethernet cable to connect up together. It's not all wireless, even though we may think it is. There always
is some type of a LAN connection that is physical, ultimately, in your networks. [Several cables and jacks display.] So what we see here, this is
what we used to call a biscuit jack. This is an RJ11 connections, both of these. Then this is an RJ45 end, [The presenter refers to a surface
mount RJ11 Jack and a wall mount RJ11 jack. The surface mount jack is square-shaped with a connector on the side while the wall jack is flat
and more rectangular, with a connector on the flat side.] [The presenter refers to a cable with a RJ45 connector.] and I like to kind of show the
difference here in size. You can see there's quite the size difference between an RJ45 and an RJ11. [The presenter compares the RJ45 cable
connector to an RJ11 cable connector. The RJ45 connector is larger and more rectangular while the RJ11 connector is smaller and squarer.] RJ
stands for registered jack, that's all it is. And when we connect up things like digital telephones, we're using a category of cable called Cat3. I
used to pull a Cat3 cable and a Cat5 cable, or 6. Cat3 is unshielded, twisted pair-rated cable up to 10 meg is the speed, not very fast, right? Not
in our gigahertz world. So we look at Cat5, went up to 100 meg, then we see Cat6 10G, Cat7 10G, Cat8, in theory, will go up to 40 GHz. So
category ratings really deal with the speed. We also have the need for shielding, whether it's shielded or unshield. Shielding could be foil or
braided. This is to protect the cable from electromagnetic interference. This is copper and it's conductive. So we're attempting to prevent
electromagnetic interference. So shielding provides an electrically conductive barrier that actually attenuates any electromagnetic waves that are
trying to get in. Here's what else the shielding does, is it keeps what's inside the cable in it right? This is not shielded, this is an unshielded
category 5 cable. [The presenter refers to an unshielded cable. Four twisted pair wires are exposed at one end of the cable.] And you can see it's
twisted, that's why we call it twisted pairs. Here is a brown/white, a green/white, a blue/white, and an orange/white. There's also a certain way to
wire these. There's two standards, and it's 568A and 568B, category 3 and category 5 wire connections. Both have the same speed, I mean,
there's no difference. The real difference is the order in which you terminate it or you put the pairs together. And the pairs are the orange and
green that are reversed on a 568A versus B. Here's the lowdown with the wiring. No matter how I terminate these, if it's an A or a B standard, as
long as I do that through the whole system. So in other words, I wire the jacks the same way as my cable ends are wired and so forth, doesn't
matter really if I choose 568A or B. My company that I worked for, we all did B. That way if another tech kind of came in behind you, they knew
the wiring was 568B with the orange and green pairs. So that's just something that is a preference, really, because there's no real difference
between performance or anything else between the two. So when we look at twisted pair cable, we've got RJ11, RJ45, our wiring standards, the
shielding versus unshielding. Then we also have plenum versus PVC, polyvinyl chloride. Polyvinyl chloride is kind of toxic when it burns, and is
not a good thing to have in an open air return. Plenum, on the other hand, is a little bit fire retardant, slow burning, doesn't emit as much toxins.
So the plenum versus PVC is really the human factor in all of this. These are all PVC cables. You usually use PVC between the PC and the wall
jack. That's very common to do because in that situation, it's a small area. So if it caught on fire, it's not like it's circulating to the whole building.
You'd want to get away from it as quickly as you could, but it's not as problematic as if I ran PVC through an open air duct return. That's
circulating the air throughout the whole building, that's now spreading those chemicals. So in those environments, that's where we rate it for
plenum. And there's certain building codes that you want to check on too. Certain building codes can be very stringent about the whole thing has
to be plenum cable, so careful about that. Finally, we talk about splitters and the effects on signal quality. I just say, don't split. A splitter is just not
something you want to do. When we want to get the speeds out of these guys, if you split it you're going to potentially lose signal quality. And
you're going to have some issues. We also look at our twisted pair cabling and rate it as, like 10BaseG or 10GBase, is what we use the term.
10GBase-T stands for this. It was a standard back in 2006, it's 10G is the 10 gigabits per second connection over an unshielded or shielded
twisted pair cable, doesn't matter. The distance is up to 100 meters or 330 feet. Category 6A is required to reach the full distance of 330 feet.
Category 6 could reach up to 180 feet, but if you have A then you get the full 330. So think about this, you don't want to run it past that. So if this
was a Cat 6a cable, then we wouldn't want to run that beyond 330 feet. So some people came up with an idea, let's just put a splitter in here so
we can extend it. Well, the problem is you lose signaling. If you want, if you have to do that, which sometimes we do, then put a repeater in. And
a repeater will be powered, and it will regenerate that electronic signal and send it on its way. Just like we have with wireless, right? We have
wireless repeaters and multiple wireless access points. And the reason we have them is because we can't reach a mile with a wireless
connection, we're limited by a distance there, too. So when you think about using your physical cable, you have to keep in mind that that also
has a physical limitation on distance. And you don't want to go beyond the rating of the cables that you're working with.
Coaxial Cable
Learning Objective
After completing this topic, you should be able to
compare coaxial cable types and connectors

1.
[Topic title: Coaxial Cable. Your host for this session is Michelle Plumb.] When we look at coax cable, let's look at some of the standards that we
have. First of all, the connector type. We have a BNC or an F connector. BNC, lots of different people think that it stands for different things, but
we'll go with the Bayonet Neill-Concelman connector. It's a miniature quick connect-disconnect. Now these are not BNC. These are actually F
connectors.The F connector is the screw type. But the BNC you would actually pull it down and pop it in. And it would pop into, connect up to
whatever it was you were hooking this into. [Two coaxial cables with F-connectors display. The presenter highlights the screws on one of the F-
connectors.] So that is the connector end, either BNC or F. Typically, most of us have F connectors if you have any kind of satellite or cable TV in
your home. The next thing is the speed, 10 meg, typically. So really high speeds when we use that coax cable connections. So this is typically
not something we use any more to hook up PCs, right, or servers because we are up in the hundred, and high gig speeds. We're not in the megs
any more. So there's that with coax cable. There's also two different ratings. And the ratings are RG59 and RG6. RG stands for radio guide. It's
an old military term. And the RG6 is what we're probably using today for cable TV, satellite, TV antennas, broadband Internet. That's what this is.
This is RG6. That's what the rating is for this. And you can actually even see when you look at your cables, it should say what the rating is on
them. RG59 is really below the 50 megahertz realm. So if you have any slower speed connectivity, that was where you used a RG59. Anything
above 50, you used the RG6. So you could get up to 50 megahertz or so with your cable connections, but again, still, we're not still not using
this. This is not common in the networking industry. We also want to see or talk about what happens with a splitter. If I want to connect these or
extend the length of this cable, that's why some people use a splitter. Well, be careful because this is rated for limited mileage and connectivity.
And this is even lower than the 330 feet. So depending upon the gauge and the connectors, and whether it's RG59 or RG6, you want to make
sure that you recognize that this cannot be strung forever and ever and ever. You have to go ahead and make sure that you look at the rating of
the cable, and you know how far you can drag that cable. Because depending upon the cable rating within the RG6 category, you may or may
not be able to string it beyond 100 feet. So you want to look at that. Look at that rating and make sure you recognize how far that cable can go.
TCP/IP Protocol
Learning Objective
After completing this topic, you should be able to
recognize the TCP/IP protocol

1.
[Topic title: TCP/IP Protocol. Your host for this session is Michelle Plumb.] When it comes to addressing endpoints and when I say an endpoint
that's everything from a smartphone, a tablet, a PC, a laptop, all of your electronic devices, printers. Everything has to have a unique address in
order to locate it. Just like when we use the mail, right? We all have to have a unique house number, street address, city, zip code, all of that
matters because it gives us that unique identity to be able to send mail to us. Well, that's the same thing that's going on here, we need to be able
to send information directly to an endpoint. And so whether that's through the Internet or within your local area network, we got to have this
unique address. What we've been using something called the Internet Protocol Version 4 for many, many, many, many, years, like back through
the 60s. [Internet Protocol Version four is also known as IPv4.] We ran out of addresses, literally a couple of years ago. [Or Internet Protocol
Version 6. Internet Protocol (IP) is used for carrying data in packets from a source to a destination.] So IPv6, you know, the newer version, has
come out and we are using this. This is a hexadecimal address that contains a global prefix, a subnet, and an interface ID that will uniquely
identify an endpoint that you might be working with. [The following IPv6 Address displays: 2041:0000:130F:0000:0000:07C0:853A:140B. The
IPv6 address has three sections: the Global Prefix is 2041:0000:130F. The Subnet is: 0000. The Interface ID is :0000:07C0:853A:140B.] So right
now we're actually using a blended solution. A lot of our routers and things have to be able to route not only IP version 4 but also IP version 6,
we're still clinging to 4. And if you looked at your home environment, most likely, most home routers use a private addressing scheme of
192.168.1 and so forth. [The Anatomy of an IPv4 Address displays. The 32-Bit Address, which consists of 4 octets, is 11000000 10101000
00000001 00000001. The Dotted Decimal Address, 192.168.1.1, is made up of 4 numbers separated by dots. The first three numbers,
192.168.1, is the Network Address while the final number 1 is the Host Address.] So you might find your addresses if you go into the properties
of your network interface card in the 192.168 range. [An instance of the Internet Protocol Version 4 (TCP/IPv4) Properties dialog box displays.
There is an IP address, a Subnet mask, and a Default gateway.] In businesses, we use the 10 network because we can actually get more
addresses, more unique addresses out of that 10 network. And so looking at IP version 4, couple of things we need to understand. It is a 32-bit
address as opposed to the 128-bit address that we have for IPv6. So we have a lot more independent addressing with IPv6 than we do with 4,
hence why we ran out. IPv4 is also kind of classed out into various subnet IDs. There's a class A, B, C and D address that we work with. And
depending upon the actual host portion of this, it depends upon how many unique addresses can come out of a particular number. And so, for
example, they have a subnet ID with 8 bits as the host portion so it can have about 254 hosts. You also have a 7-bit address. You have the ability
to take these addresses too and subnet them. [A table illustrates the address classes. The table has four columns, each representing 8 bits.
Each row gives the Subnet mask, 32-Bit Address, number of Subnet ID bits and the number of Host ID bits. Row one has no Subnet ID Bits,
eight Host ID Bits, one Subnet, and 254 Hosts. The associated Subnet mask is 255.255.255.0. The 32-Bit Address is
1111111.11111111.11111111.00000000. Row two has one Subnet ID Bit, seven Host ID Bits, 2 Sunbnets, and 126 Hosts Each. The associated
Subnet mask is 255.255.255.128. The 32-Bit Address is 1111111.11111111.11111111.00000000.] And so if you want to learn subnetting, that's
something that you'll learn in the I, C and D courses or the Cisco courses. But for now, what we need to understand is that our home addresses
and our work addresses probably are IPv4. It contains an IP address, a subnet mask and a default gateway. The default gateway is the router
address that gets us to the Internet. That's what a default gateway address is. The subnet mask is basically like the street we live on, and the IP
address is the unique house number. That's kind of the way to think of the breaking out of that IPv4 address. And when we address things, of
course, everything has to have a unique address. So we have to have enough unique IP addresses within the same street so that we can talk to
each other like in our home network just to keep that visual simple. In a home network, you might have what, 20 devices that have to have
addresses. So our subnet, our street that we live on can contain 20 of those IP addresses. And then, of course, our default gateway is usually
our service provider that we're connecting out to the Internet with. And when we look at having that street and house number, and we look at the
subdivision of an IP network, we just have to keep in mind that IPv4 is kind of on its way out. The last unique addresses were handed out a
couple years ago, but we're still making it work. One of the ways that we are making it work, if you're wondering, well if all the addresses are
gone how do we have a unique address? Well, we also took those individual routable addresses and added port numbers to them. So now you
can have an IPv4 address along with a port number that gives you a unique location and a unique place to stream information back to you at
your home network, for example. So that's how IPv4 continues to live on with port address translations, or PAT is what it's called, in our networks
and in our home networks. But someday we're going to have to give it up, we are. But for now we're still clinging to it.
TCP and UDP Ports
Learning Objective
After completing this topic, you should be able to
list TCP and UDP ports

1.
[Topic title: TCP and UDP Ports. Your host for this session is Michelle Plumb.] The TCP/IP protocol suite is kind of like the umbrella. And
underneath that umbrella are Transmission Control Protocols and User Datagram Protocols. What these protocols are used for is how
information is transmitted. [Or TCP.] Transmission Control Protocol works like this, I send you a packet, you send me an acknowledgement back.
I send you two packets, since that went so well, you send me an acknowledgement back. And so it scales up, we just keep getting larger and
larger amounts of sending and then receiving. Now, here's what happens. We go into TCP slow start if I don't hear back from you. Wait a minute,
I sent 1,024 packets and I don't hear a response back. All right, let me start from the beginning. Here's one and I get an acknowledgement, and
here's two. [UDP is the acronym for User Datagram Protocol.] UDP works like this, the User Datagram Protocol says, here it is. Good luck, see
you later. The other thing that we use with TCP and UDP is ports. And these unique ports are what we transmit on. And all of these different
protocols have their own ports assigned to them. There's a standards body out there. And it says that if you use the file transfer protocol, or FTP,
that's going to use port 21. If it's the Secure Shell Protocol, it's 22, [Or SSH.] Telnet's 23,SMTP for mail is 25, DNS is 53, HTTP is 80. So all of
the different protocols, and this is not all encompassing, have their own unique assigned ports of the well known protocols. [Other examples
include POP3 uses 110, IMAP uses 143, HTTPS uses 443, RDP uses 3389, NetBIOS/NetBT uses 137 to 139, SMB/CIFS uses 445, SLP uses
427, and AFP uses 548.] So if you're ever looking for a firewall, that's how a firewall can block things. It looks for a port number, and it says, wait,
we are going to block POP3. So we're going to block port 110 on this router to stop all POP3 traffic from coming in. So that's one way that these
TCP and UDP ports can be utilized when it comes to transmitting data.
TCP/IP Protocol Support
Learning Objective
After completing this topic, you should be able to
list various protocols using TCP/IP

1.
[Topic title: TCP/IP Protocol Support. Your host for this session is Michelle Plumb.] We always talk about TCP/IP as kind of like this protocol
suite. There are a lot of embedded protocols built around the TCP/IP standards. So that we can easily, quickly access information such as
DHCP, Dynamic Host Configuration Protocol. This is what assigns addresses to end points. It uses something I call Dora the Explorer. You get a
DHCP broadcast that the client says, is anybody out there that can give me an address? Then DHCP responds with an offer. And then we get a
response back, and then the acknowledgement, hence the Dora the Explorer. That's how DHCP works. DNS, the domain name system, converts
Alphabetic names into numeric addresses. [A diagram illustrates the DHCP processes. First the client discovers the DHCP server. Next the
DHCP server sends an offer to the client. Then the client accepts the DHCP offer and finally, the DHCP server acknowledges the client.] When
you go and do a search, and you find somebody's website, like www.wikipedia.org. That's not how they're known, we've talked about this. IP
addresses, that's the key. How do we take wikipedia.org and turn it into that IP address? Well, there are name servers. And the name servers
break down into the .org. We have wikipedia.org, then we get the .org environment. And then we find the root name server. By that, we find the
actual name resolution to wikipedia.org to a public IP address so it can be found. So we're actually not using names to find things on the
network. [A diagram illustrates how DNS recursers and nameservers are used to convert alphabetic names into numeric IP addresses. In the
diagram, the DNS Recurser wants to find www.Wikipedia.org. It sends a message to the Root nameserver at 198.41.0.4. The Root nameserver
sends a message to the DNS recursers to try 204.74.112.1. The DNS Recurser sends a message to the .org nameserver at 204.74.112.1. The
.org nameserver sends a message to the DNS recursers to try 207.142.131.234. The DNS Recurser sends a message to the Wikipedia.org
nameserver at 207.142.131.234. It sends a message to the IP address for Wikipedia.org to the DNS Recurser.] We also have the LDAP protocol,
the lightweight directory access protocol. This is used by Microsoft's Active Directory. So the servers that we log into on a daily basis store our
information using the nonproprietary. So it's out there for everybody to recognize the structure of a Lightweight Directory Access Protocol
Environment. We have domain controllers, organizational units, canonical names, user IDs. And that's how the database is broken out, so we
can store individual names that we can locate, even resources on a particular file server. [An LDAP Directory tree using domain-based naming
displays. The first three branches of the tree are dc=net, dc=com, and dc=org. The dc=com branch has a sub-tree labeled dc=example which
represents an organization. The organization branches into two organization units: ou=People and ou=servers. The ou=People branch connects
to a Person: udid=jsmith.] SNMP and SMB, these are helper protocols. So this is something you and I might use because we're using this for
network management. [SNMP is also known as Simple Network Management Protocol.] SNMP can collect information from network devices,
routers, switches and hubs and so forth and collect that information up so that we can review it. They do it during trap events. And we can look
up that information to help determine and troubleshoot something that might be going on in the network. [A diagram illustrates the messages
sent between an SNMP Manager and Managed devices. The SNMP Manager sends a message to the SNMP Agent: Get the value of a MIB
object. The SNMP Agent requests the information from the MIB object. The MIB object sends a response to the SNMP Agent and the SNMP
agent sends a response to the SNMP Manager. A second SNMP Agent communicates with an associated MIB object. The MIB object sends a
response to the SNMP Agent and the SNMP Agent sends a message to the SNMP Manager: Trap (event notification). The SNMP Manager
sends a message to a third SNMP Agent: GetNext (read the rows of a table). The SNMP Agent requests the information from the MIB object.
The MIB object sends a response to the SNMP Agent and the SNMP agent sends a response to the SNMP Manager.] [Or SMBs.] Server
Message Blocks is the network file sharing protocol that's been implemented by Windows, or Microsoft, and this is a request-response type
protocol between the client and the server to gain that information. We also have the Common Internet File System. [Or CIFS.] This is another
standard way that computer users share files across the network. And we use the TCP/IP environment to do this. We have an IP address and it's
either TCP or UDP in the connection-oriented or connectionless environment. And then we look up the actual file or we receive the actual file
that someone might be sending to us. [A diagram illustrates the CIFS file-sharing protocol. The CIFS/SMB connects to TCP, NetBIOS over TCP,
NetBIOS over NetBEUI, and NetBios Over NW/IPX. The TCP connects to the IP which connects to the Physical Media. NetBIOS over TCP
functions in the same way. The NetBIOS over NetBEUI connects directly to the Physical Media. NetBios Over NW/IPX connects to IPX which
connects to the Physical media.] We also have security. This is just one of many, but SSH is a Secure Shell environment that encrypts
information. And we use this between clients and servers, typically, so the client initiates a connection. [SSH is a cryptographic network protocol
for operating network services securely over an unsecured network. The best-known example application is for remote Login to computer
systems by users.] The server is going to send a public key. It's a unique hashed algorithm that the client will receive. And then they'll either
accept it or not. So if this client says yes, that's a legitimate public key, I recognize it. They'll negotiate parameters to open a secure channel, and
the user will log in to the server to authenticate. So that's basically, the basic, basic structure of how SSH works in our environments. Also, we
have Apple, right? Can't leave this out. AppleTalk is the one that I'm familiar with. I still call it AppleTalk, but it's the Apple Filing Protocol, or AFP,
proprietary for Macintosh environments. [An AFP file access model displays. There is a Workstation and a File server. In the Workstation, a
Program uses native file system commands to request a file from the Local file system. The Local file system accesses the file on local Volumes
and sends the native file system commands to an AFP translator. The AFT translator translates the native file system commands to AFP
commands and sends the command to the Network File server control program on the File server. The File server control program uses native
file system commands to request the file from a local file system. The Local file system accesses the file on the volumes.] And again, this is just
a way to look up files and information on our end points.
TCP vs. UDP
Learning Objective
After completing this topic, you should be able to
compare TCP and UDP

1.
[Topic title: TCP vs. UDP. Your host for this session is Michelle Plumb.] The TCP/IP protocol has the connection oriented and the connectionless
environment. Connection oriented, we have a header, with a source, port address, destination port, sequence numbers, acknowledgement
numbers, window sizing, checksums, and some padding. [A TCP header diagram displays. The diagram has four one byte sections and six
rows. Row one has the Source Port Address and the Destination Port Address. Row two has the Sequence Number. Row three has the
Acknowledge Number. Row four has H LEN, reserved, CONTROL, and Window Size. Row five has Checksum and Urgent Pointer. Row six has
Options and Padding (0-40 bytes).] And with this, we have a state of, I send you a packet, you send me an acknowledgement, and it's called
windowing. There's actually an RFC out there that explains the size these windows can grow to. So as we have a flow or a conversation, if one
worked, then I'll send you two, and then I get a response. And then four and then I get a response, and then six, and then so forth on up. But as
soon as I don't get a response, I go, something's wrong. And I immediately go into TCP slow start. Which means I go back to one packet, get an
acknowledgement, two packets, get an acknowledgement. And so that can be a traffic problem on your network. If all your TCPI connections go
into slow start at once because of some type of traffic jam and we didn't get the acknowledgements, that can cause some backups and some
problems and some dropping of packets and things. [A diagram illustrates a connection orientated TCP. There are two TCP States the first is
CLOSED and the second TCP State LISTENS. The first TCP sends SYN: SEQ=1000, CTL=SYN. The SYN is RECEIVED and the following is
sent back to the first TCP: SEQ=720,ACK=1001, CLT-SYN pipe character ACK. The connection is ESTABLISHED. The first TCP State sends
SEQ=1000,ACK=751, CTL=ACK.] So we looked at connectionless, UDP. It's kind of rude but it's like, send it to me. I don't care, just send it. Just
send it, just send it, just send it. And literally UDP can starve out TCP traffic. The folks at MIT actually did a study on this. And they showed how
the UDP traffic could actually just flood the network because it doesn't care. It just keeps transmitting, transmitting, transmitting, transmitting.
Where TCP is kind of that more polite environment that says, well, did you get it? And until I get an acknowledgement, I'm not going to send you
more. Or I'm just going to repeat sending you the same thing. So UDP literally can stop the TCP traffic out of existence. Because it just says,
keep sending, keep sending, keep sending. Where the TCP protocol is the one that is waiting for an acknowledgement. So with UDP, for
example, we use this for voice and video traffic. Because if you think about it, I always joke in my video and audio classes about, what's the
router going to do? Ask you to repeat word in the fifth sentence and send it out, right? No, so with UDP, it works perfect for voice and video traffic
because there is no re-transmission. It doesn't help to re-get that packet. So with TCP, though, if it's data and we're missing a piece of that data,
retransmitting that data can be done very easily. And it's important that we do get the proper data, right? So that's why with connectionless
environments we see that used more with things like audio, conversations, and video. And we use the connection oriented environment for data
that can be retransmitted and reestablished.
Networking Tools
Learning Objective
After completing this topic, you should be able to
contrast the various networking tools

1.
[Topic title: Networking Tools. Your host for this session is Michelle Plumb.] Here we are talking about the physical tools that we use in our
networks. And one of the things that you may be doing and may not, a lot of times people just purchase cables, but you may create your own
custom cables. I mean, I do, I have a crimper and a cable stripper in my home. Because I want to make the proper length of the cable if it's a
RJ45 connection or RJ11, you know, whatever the connection is that I'm trying to establish, I'll make my own cables. So you need the proper
tools. We see this is an actual RJ11 RJ45 crimper. [An image of an RJ11/RJ45 crimping tool displays. It has two handles and a crimping section
with three square-shaped holes that differ in size.] So this would make network cables and phone cables. And you also need to be able to strip
the ends of the cable off to get into the RJ11 and RJ45 plastic end, so you have to strip off a little bit. So built in to these crimp tools typically is a
cable stripper so that you can make the cable. We might also want to check signalling. Again, I always say it's electronic signalling, it's ones and
zeroes, unless we got fiber so we'll leave that for a moment. But you might need a multimeter to determine the amount of voltage coming out. [A
multimeter displays. It has an LCD screen, buttons, a rotary switch, a positive probe, and a negative probe.] You might use a tone generator or a
probe that would help you to determine where the cable is, if there's a cable break. Sometimes you can use, if you're pretty handy with it, the
tone generator, figure out where in that cable line there might be a break or a problem. Same thing with a probe. So these are different
networking tools, you may or may not have them in your tool belt. There are cable testers and loopback plugs themselves. [A network cable
tester and remote display. The remote has several lights labeled 1 and 2, 3 and 6, 4 and 5, 7 and 8, and GND, respectively. The cable tester has
several lights labeled 1 and 2, 3 and 6, 4 and 5, 7 and 8, GND, and POWER, respectively. It also has a GND ON/OFF toggle switch and a
POWER GND ON/OFF toggle switch.] So you can actually plug the cable into these cable testers and get readings and see what the pinouts
are. A loopback plug, basically it looks a little differently than you see on screen. It has either four or six copper connectors, and then it has two
wires that loopback so that you can actually plug that in and have the signal come back in. That's what loopback stands for, coming back to you,
right? So you create this little loopback plug. [An image of a loopback plug displays. Two wires exit and re-enter the plug creating a loop.] I use
them a lot in my telecommunications gear to simulate connections out to the public switch telephone network. I also use them in our networking
environment to signal coming back into the network card to see if the network card is working. Used to be back in the old days, we used to have
races to see who could punch down a 25 pair cable to a 66 block the fastest. [A punch down tool and punch down bit display. The punch down
tool has a handle and a punch down bit. The punch down bit has two ends.] And literally, what you're doing is you're taking cable pairs and
you're pushing them into these clamps. And so, that's what this punch down tool is used for. You punch down into that 66 block, that's going to
hold connections for either your network or maybe your phone system out to the public switch telephone network. And finally, we now have Wi-
Fi, right? So probably, one of the better things to have in your tool belt is some type of Wi-Fi analyzer so you can test things like signal strength.
[A Wi-Fi analyzer displays. IT has two antennae, an LCD display with wavelengths and a meter, and a keypad.] That's one of the biggest got you
in my opinion when it comes to Wi-Fi, is the signal strength. In my home, I have situation where my front area of the house has the lowest signal
strength and sometimes it even just drops off. So we have a repeater now that helps to boost that Wi-Fi signal. And so by using these Wi-Fi
analyzers in your network, in your office environment, or your home environment, it can help you determine where the weak spots are in your
network.
Wi-Fi Standards 802.11
Learning Objective
After completing this topic, you should be able to
list the various Wi-Fi standards

1.
[Topic title: Wi-Fi Standards 802.11. Your host for this session is Michelle Plumb.] If you have a smartphone or a tablet, you have wireless
devices, right? Everything in my home practically is wireless, even at the office. When I do travel into the office, my laptop connects up
wirelessly. So, wireless standards, there's a standards body. It's the 802.11 standard that defines wireless LAN specifications. We started with
802.11, we don't even have that on the slide because that was the old one or two megabit per second transmission speed. Then we had A, B,
and G, which gave us anywhere from 11 megabits per second for B and 54 on the A and G. But the difference between them was the spectrums
that they transmitted on. Either 2.4 gigahertz or 5 gigahertz. [802.11a - up to 54Mbps and signals in a regulated frequency spectrum around 5
GHz. 802.11b - up to 11 Mbps 2.4 GHz. 802.11g - bandwidth up to 54 Mbps, and it uses the 2.4 GHz Wi-Fi band.] Here's what used to happen.
My microwave used to interfere with the 2.4 gigahertz spectrum. And if you build electronics, whether it's a microwave, a cordless phone, a wired
phone that you might have, all of them work on a certain frequency or spectrum. And so they interfere with each other. So what the standards
body has tried to do was make it so that all of these different appliances worked in different spectrums. So if you're having problems like with
interference, it's probably at the 2.4 gigahertz range. You can skip or change that to a 5 gigahertz channel, that might give you better reception.
So you might think about that, even in your networks that can happen. But as we move on up, we're now up at the N and AC standards. So N
goes up to 300 megabits per second, backwards compatible. Everything's pretty much backwards compatible. A and B could be a little testy, but
usually all of your newer wireless devices, transmitters, routers would be backwards compatible. But you want to check that, make sure you look
at your gear and if you know if you have older things that might be in the A or B spectrum make sure that that wireless connection is going to still
work. [802.11n is backward-compatible with 802.11b/g gear.] So the AC is up to 1300 megabits per second on the 5 gigahertz band plus about
450 on the 2.4 gigahertz band wave. So as we move forward, as you can see, the need for speed, I call it, just keeps increasing. Because let's
face it, most of our stuff is wireless now, right? We're doing away with the cables, we are wireless. [802.11ac has dual-band wireless technology,
supporting simultaneous connections on both the 2.4 GHz and 5 GHz Wi-Fi bands.] And so, these wireless standards are probably just going to
keep increasing and increasing due to the technology and the speed requirements that we are all demanding.
Wi-Fi Encryption Types
Learning Objective
After completing this topic, you should be able to
describe Wi-Fi encryption types

1.
[Topic title: Wi-Fi Encryption Types. Your host for this session is Michelle Plumb.] Wireless is adapted everywhere, right? We have access from
our cell phones and our smart devices, our home environments. I have probably 80% wireless connections, and maybe 20% of our computers
are wired. And so we also see this in our networks in our businesses, right? Where, you know, we might have more wired in our business
environment, but we still have wireless. So one of the big things if you read the news, watch the TV, you'll hear about the hacking, right? And
you'll hear about the breaches. And one of the easiest areas that people can hack into is your Wi-Fi networks. So we want to secure them, the
way we secure them is through encryption. And wired equivalent privacy is the oldest method. [Or WEP.] So you can imagine, it came about in
the 90s, it's probably not the best solution. So the WPAs, the Wi-Fi protected access versus Wi-Fi protected access II, WPA2 has a 256-bit
encryption key. And that longer key improves security. And it takes that much longer for someone to try to figure out what that 256-bit key is. One
of the problems we have is that the devices you may have can't support some of these different encryption types. Because you might take these,
and you might combine them with things like TKIP and AES. The temporal key integrity protocol and AES, which is the advanced encryption
standard. Those can be sometimes kind of merged into WPA2, for example. But the problem is not every access point, not every end point can
support the higher standard protocols that might help you keep things a little more encrypted. So that's what the problem is that we run into, it
really is. It's not so much that you and I don't want to turn on a lot of this heavy duty encryption. Like TKIP employs a per packet key system that
is way more secure than a fixed key, which is what the W-E-P system or WEP system use. TKIP was later superseded by AES, but the problem
again is, do your devices support it? That's the key, you want to try to go, though, to the highest key integrity that you can. So if WPA2 might be
it, so that all your devices can connect up securely, that might be what your choice needs to be. But just remember, these are the standards. You
need to look at the router itself, the wireless router, to see what standards it supports. Then you also have to look at the actual end points that
are connecting up the clients. So that you see if the clients can support these different encryption connections back to the wireless device. So it's
kind of a two way street. You got to have it on the router to support it, and then you have to have it on the end point to be able to understand it as
well. So that you can do these combinations of, you know, WPA2 with AES. You know, that might be a really good one to choose. But if your end
points don't support it, or your router doesn't support it, then you're going to have to go with, I call it the highest least common denominator,
right? Or most common denominator, I should say. So whatever that highest standard that you can support on all your devices, that's what you
want to go for, for your Wi-Fi encryption.
Exercise: Applying Networking Tools
Learning Objective
After completing this topic, you should be able to
distinguish between networking tools

1.
[Exercise: Applying Networking Tools. Your host for this session is Michelle Plumb.] All right, we're going to play some kind of what if games here
for our exercise. I've got three sets of tools sitting on the display for you. [A multimeter, a crimping tool, and a wire stripping tool display.] And I'm
going to ask you some questions and then you can pause, think about it, and we'll come back and give you the answers. So my first question is,
I'm going to repair this cable, [An RJ45 network cable displays.] which one of these tools could I use to reconnect an end to this RJ45
connection? Now, there's a couple here that you could use, that I'm looking at on screen. So I would accept one or two answers for that. My next
question is going to be, I've got my motherboard, and I suspect that there's a problem in the circuitry. Which one of these tools might help me
determine if there's a voltage situation going on, maybe on that motherboard, or a connection that isn't working properly, which one of these tools
could I use? Okay, ready? Pause your video and think about that for a moment. All right, coming back. We have a crimp tool that would allow us
to repair this or recrimp it. [The presenter shows the network cable.] And so that's what we see sitting here. [The presenter refers to the crimping
tool.] Now, this is also a tool that helps you select the thickness of the wire and then strip the plastic sheathing off of it. So you could use this in
conjunction with your crimp tool. [The presenter refers to a wire stripping tool.] Now, the second question was what about my motherboard and
any problems that I might see here? [A motherboard displays.] And again, be very careful when you're working with some of these tools around
electronics. But that might be when you would use one of your multimeters to determine the voltage that's going through a particular connection.
[The presenter refers to the multimeter.] But again, I always say safety first. And if you're not comfortable with that, then don't attempt to start
sticking probes on a motherboard to determine the connections. But it's always safe to if you unplug everything. And then you start connecting
up your probes to see where or trace where that connection might be failing

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