### CCNA ICND1

Course
Time
23 hours 18 minutes
Difficulty
Beginner
CEU/CPE
14

### Video Transcription

00:00
Hello. Welcome back to ice and you won. Interconnecting Cisco Networking devices apart one This episode 412 Turning sub net and address needs
00:09
And I am trend there when I'll be restructured for this course the last video went over Just the lesson one or 4.1 overview is absolutely determined. What you need in addressing space
00:19
and learning objectives were gonna learn why we would have sub net a classical network and how we're going to sub net with same running from ask. We're gonna get into a variable length masks in the next video.
00:31
Quick pre assessment. Here. Hopefully, you should remember which one of these is not a Class B
00:37
00:38
So hopefully remember back to your class networks and see which one I'll give you. Heather's too.
00:44
We're not close B.
00:48
All right. It is 1 26 12 69 65 11 26 times. 59 78.
00:56
All right, so is submitting. Uh, I'm sure everyone's heard. You know
01:00
about it. There was a little afraid. So sub sub net always is subdivided network. So imagine taking your normal network and just breaking that up into smaller networks, right?
01:14
So cider is also called classes in her domain routing. I'm sure you've seen it on some of my lab diagrams, whereas slash a slash 16 slash 24. So what this is representing is slash eight is the number off network bits
01:27
on the better towards the address so slash eight, That would point towards a 2 55 000 sub net mask.
01:38
Because remember, if we go back to that binary talk that we had back then,
01:42
uh, all the all eight binary bits added together, it will be 2 55
01:48
which were equal to 1 56 dresses, zero through 2 35
01:52
Um, the same thing was 16. You have eight bits which, you know half of the 32 bit address is gonna be to be divided to divide 00 24.
02:02
Dubai fired to hired to provide zero.
02:05
So Class A's going to slash aids class B slash sixteen's Class C
02:12
is going to be your slash 24. So there's a little bit of review for you,
02:16
so we're gonna go ahead and jump into why we would submit.
02:23
So think about a 10 dot network right if we just have
02:28
every single person on 10.0 slash eight, so only the 10 dot parts the first octet is the network portion.
02:36
We have just over 16 million hosts and each network.
02:40
Now imagine
02:43
if someone were to send a broadcast and everyone's harping and everyone's broadcasting. This would just flood the network. Every single person would have to process that broadcast. It would be
02:53
absolutely insane.
02:53
So what we can do is we can submit that 10 dot into a slash 24 like we've done in some of the labs. So we have just over two million networks. But now we have 256 host for network, which now, instead of two million people or 16 million people processing a broadcast, we only have 256 people processing a broadcast.
03:15
So now if we look at, you know,
03:16
just looking at that third octet, you know, we could have sales said
03:20
10 010 through, you know, 10 1.2 55. So that is your block
03:25
space that you have for that one sub net. Is that slash 24 7022 55.
03:31
Same thing with accounting I t department. So we can go all the way down to tend to for declared that to be divided zero
03:39
through to pretend to be defied to be divided. To notify slash 24
03:45
slash 24. We're gonna have
03:47
three octet. It's air set up for the class or for the network. Excuse me.
03:54
So why we said that it's a
03:57
It's about efficiency. So we can break apart the network by departments by devices, by anything you really want to.
04:04
And we don't have broadcast storms toe where every single person has the process. The broadcast at the I P cameras or the printers air pushing out,
04:15
you know?
04:16
All right. So what do we need to determine?
04:17
We need to figure out how many hosts we have. Ah, we need to figure out how we want to. So divide them. Whether we want to do about apartment, whether we want to do about printers or devices.
04:29
Um, how many I ps air gonna be used? Because, remember, you have to have i p's between routers for routing.
04:34
You need to have. You know, if you're gonna have a management I P address on it. Switch.
04:39
You're gonna need one for that. So, you know, um,
04:42
you see if you have multiple i p addresses for servers,
04:45
There's just things you take into account.
04:47
Um, and then we got Look at how many subjects who we need here. So
04:51
for now, we're gonna assume all this is on the line One. We're not going to go crazy here,
04:57
so I mean,
04:59
think about it. We need a network
05:01
over here.
05:03
What? No network here. And we need a network over here,
05:08
so we just need three. And let's say this is just, ah slash 24 for now,
05:12
so we could break this up. And these guys only need two addresses. This. Say this guy needs 56
05:18
and he needs 111.
05:23
Right?
05:24
So each one is different, so we'll get into the variable length and why
05:28
we can actually utilize those small block spaces.
05:30
But, you know,
05:33
for now, we're gonna see more of you and one. Um So we need three sub nights. We have
05:39
you know, how many total hosts? How many? We got A look at how many hosts per sub net. We're gonna be utilizing.
05:46
And what we want to use is we want to look at it and say, OK, so
05:50
we have 100 and 11.
05:54
That is the max eyes that we can use. So when you look at what box eyes
06:00
or how many bets when you borrow to get the
06:01
most efficient use of our space?
06:04
So if we just say,
06:06
borrow two beds here
06:09
would give us
06:12
06:15
So then we could, you know, split this up. Between these three,
06:19
we could use each one to have on 28. Just sees the same mask,
06:24
so that would be into a slash
06:27
25.
06:29
So the total is your mayor back, we have 32 bits total and an I p V four address. So these 32 bits are split between the network, the sub net and the host bits.
06:40
Okay, think about that for a second.
06:42
And I'm gonna go ahead and show you the trick that I use
06:46
to help me pass, uh, see sense
06:47
and to help me remember submitting. So the first thing I did when I got in this exam was draw out this
06:56
kind of chart. I guess you'd call it,
06:58
Um,
06:59
but I'll explain it here in a minute. Don't worry.
07:00
So what you can say is,
07:02
let's say we have tender at 120 slash
07:09
24. We'll just do a slash 24 for now to make it easy. So come back over this chart. We'll say we have 24 network bits.
07:17
So remember that we had to take this whole thing out of 32.
07:21
And let's say we wanna have a we need 60 addresses is the largest block that will need. So you 60 eyepiece
07:30
in each block.
07:33
So you come over here and we'll say, OK, 60 can't fit into here. 60 campaign in here up. 60 could fit in here.
07:43
So we got 123456 So we had six toes. Spitz,
07:48
which would leave us, what? 32
07:51
minus six months? 24.
07:54
We leave us to bits, so we're going to hear
07:57
count. 12
07:59
24
08:01
That would leave us four sub nets with a 64
08:07
minus 2 62 hosts. So the block size of 64. But we can have 62 eyepiece
08:15
and each sub net.
08:18
So I'm gonna go ahead and erase all that again. We'll go over it quickly again here. So let's say we got 17 to that 16. That one.
08:28
That zero slash 24.
08:31
I would say we have 120 I p's
08:35
in each block that we need.
08:37
So we go over to our charge. No, can't fit. Can't pick you. It's all the way down here. Oakley fit here.
08:45
So we got 12345677 hosts
08:50
24 for the network
08:54
because of the slash 24 it here,
08:58
which would leave us one sudden at bit.
09:00
We'll be right there. So which would leave us to sub nets?
09:03
We would have 100 and 28
09:07
locks, eyes minus two for the host her for the Network I. D. And the broadcast address,
09:13
which would leave us 126 eyepiece in each sub net.
09:20
And this is the If you're a math guy, I can't do it. I can't do this kind of math in my head. Do the exponential stuff. But the way you can figure out your hosts is to raise two H,
09:31
which would be your host bits.
09:33
So to raise 27 minus two,
09:37
so is the same thing. Is this?
09:39
Um
09:41
I'm just visual. I can't do the math that quick. This was just a very quick for a way for me to draw it on the
09:46
dry erase board thing that they gave you during the exam. And I could just go through it quickly. Subject and network.
09:52
Um,
09:54
that was what I did. If if that doesn't work for you, um, please look around on the internet. Um,
10:00
because once it clicks, it should click. Eventually don't come through and you'll be like, Wow. Okay, now I got it.
10:05
And this was the way that works for me.
10:09
So hopefully it helps you,
10:11
and we'll go on to the
10:13
quick exercise here.
10:16
All right, So let's go ahead and figure out what is our largest sub net here.
10:22
So I see. We got 100 26 1 21 1 25 Okay, so 1 26 again. Your largest.
10:31
So I'm gonna draw out the
10:33
chart here. 248 16 32
10:39
64 1 28 to 56.
10:43
I generally only need to go to about 2048.
10:46
That will leave you plenty. But I'm going to end knowing on the need to go if I told you this.
10:52
So if you go here
10:52
12 we gotta go all the way to to 36 because,
10:58
you know, we don't really gotta go 1 28 Okay,
11:01
so we're just going to hear
11:03
It's our network. We have 16.
11:05
1234567
11:09
There's gonna be our host bits
11:13
and see how many we need for sudden it. So
11:16
32
11:18
my 16 My seven
11:22
three b nine.
11:26
So nine cent,
11:30
which would leave us
11:33
a. Remember, this would be a block size of 1 28
11:37
And this would leave us 123456789
11:45
So there was 512 sub nets.
11:50
Remember, we need to have a network here.
11:54
You have a network here,
11:56
Here, here,
11:58
here,
12:01
you know,
12:01
So we clearly we have enough, sudden. It's, um
12:05
doesn't mean eight is not even close to fight 12. But we have
12:09
How much room for growth. Now? We didn't just utilize, you know, one class full network.
12:16
We have
12:16
you know, just 500 subjects left that we can utilize instead of just throwing everybody in one space. Now it's actually getting utilized properly,
12:28
So we'll go ahead and move into the post assessment here.
12:31
What is the sub net mass with a cider address of slash eight. Look a quick where we talked about this in the beginning. The lesson here. Give you a few moments.
12:41
All right, it is 225000
12:46
In the next episode, we're gonna look at V l s m R variable length sub net masks.
12:52
And as always, if you guys need help, have any questions? Feel free to shoot me. Message. Otherwise, thank you for watching this. And I look forward to seeing you next one.

### CCNA ICND1

This course will enable students to understand virtualization and cloud services, and network programmability related to LAN, access and core segments.

### Instructed By

Trenton Darrow
Network Engineer at NCI Information Systems, Inc
Instructor