Network Concepts and Terms

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Time
21 hours 25 minutes
Difficulty
Intermediate
CEU/CPE
21
Video Transcription
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>> Hey, there Cybrarians and welcome back to
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the Linux plus course here at Cybrary.
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I'm your instructor, Rob Gells.
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In today's lesson we're going to be
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covering network concepts and terms.
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Upon completion of today's lesson,
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you are going to be able to understand
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the concepts of things like
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local host versus Unix sockets
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as well as interface configurations.
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Then we will get into some key
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networking terms like throughput,
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bandwidth, the name resolution.
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Finally, we're going to determine how
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latency, saturation,
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packet drops and timeouts affect network performance.
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Let's talk about network concepts first.
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One thing that we should definitely be aware of
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is the concept of the local host.
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This is the local network interface.
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It's sometimes also known as
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the loopback or home network.
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You'll see this referred to in terms of
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IPV4 at address 127.0.0.1
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is the home network and
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the colon colon one address is the IPV6 address,
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that is for the home network.
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Now, traffic that is sent to
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local hosts kept internal to the system,
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but it acts exactly like any other network traffic.
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Now by comparison, a Unix socket is an endpoint that
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allows processes on the same system to communicate.
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Because we're on the same system,
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these are referred to as inter-process
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communication or IPC,
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and so Unix sockets are known as IP sockets as well.
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But unlike local host traffic,
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this traffic doesn't travel across network interface.
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It's just communication between
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two processes on the system.
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Now, another concept we should be aware of is the port.
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We've seen the port before.
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Port is used to identify
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the service that transmitting data.
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For example, we know that port 80
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is used for HTTP traffic,
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whereas port 443 is used for HTTPS.
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Now, the port number is combined with
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an IP and forms what is called a network socket,
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and then that can be used by a program or
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service as an endpoint for the network connection.
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Then finally, interface configurations assigns settings
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from a network interface or to
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a network interface such as IP,
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net masking gateway,
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and a lot of these concepts,
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if you recall, we talked about
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networking way back in Module 3.
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If any of this is unfamiliar to you,
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definitely take a look back at that module.
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Now let's talk a little bit about
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some key network terms and we're going
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to see how these terms are
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related to some networking issues.
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Bandwidth is the max amount of
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data that you can transfer over and network media,
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that means over a wire of any type.
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It could be Cat5,
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could be fiber, could be anything.
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That's just the media that we're using.
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Now throughput is the amount of data that
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actually is going to pass through that media.
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Name resolution is used to handle converting
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an IP address to
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a host name or a fully qualified domain name.
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A lot of times people will just abbreviate that
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as FQDN because it's easier to say.
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Remember from what we talked about in Module 3,
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host name resolution is handled
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through etc/hosts as well as etc/resolved.conf.
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Then routing, pretty familiar with that as well.
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But routing is the process of sending data
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from one network to a different network,
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and that's usually done via a router or gateway.
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We use the route and netstat
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commands to view that routing.
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Let's talk a little about network performance issues.
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Now, saturation occurs when
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the throughput reaches the max value or bandwidth.
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Remember, throughput is the amount of data
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that you can actually get through a medium.
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It could be, like I said,
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Cat5 cable, Cat6 cable,
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could be fiber, whatever.
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Then as it reaches bandwidth,
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bandwidth is the maximum amount of
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transferable data that you're going to
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ever get through that medium.
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As throughput, which is the actual data transmitted,
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starts to reach the max,
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it creates what's called network saturation,
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it causes the network to be slow.
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Latency is just the time between sending
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a packet and the destination receiving it.
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The higher latency is,
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the slower the longer it takes
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for that packet to reach from one end to the other,
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and the lower latency is the faster
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that that packet travels from
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the source to the destination.
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Highly Latency is often caused by either saturation,
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which we just talked about, or just low bandwidth.
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Now, packet drops occur either when a system doesn't
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respond to a packet
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or a packet fails to each destination.
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For example, when we're talking about ping,
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we use paying a lot to test network connectivity,
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but we can actually have ping
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fail for either one of these reasons;
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someone can turn off ICMP echo responses,
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and so when you go to ping something,
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it will respond because it's just not responding.
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It's still been told not to.
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Or the system might actually be down,
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and that's why the packet isn't reaching
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>> its destination.
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>> Now, timeouts are actually
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software components and they're used
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to set a preset time period
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for handling unplanned events.
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Basically, if you are painting something and it
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doesn't respond in a certain period of time,
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you might get a timeout message back,
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and that's just a message back
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from the ping command saying,
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"Hey, I've waited this long and nothing's happened."
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You're not going to get a response. We can use
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this to determine whether a packet drop has occurred.
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In today's lesson we covered
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some fundamental concepts of networking working as well
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as key networking terms that we should know
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when we're discussing networking troubleshooting,
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and then we also went over
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some common network performance issues.
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Thanks so much for being here and I look
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forward to seeing you in the next lesson.
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