1
00:00:00,260 --> 00:00:01,060
Okay.

2
00:00:01,070 --> 00:00:07,040
I know there are a lot of terms and conditions, so let's just break it down with a real world scenario.

3
00:00:07,850 --> 00:00:14,750
Although the standard for A and B class networks specify eight and 16 bit masks respectively.

4
00:00:15,080 --> 00:00:23,360
It's common to assign non-standard masks for subnets, resulting in much more limited address spaces.

5
00:00:24,200 --> 00:00:33,740
For example, using ten point Xinyi dot zero slash 24 results in 256 host company subnets.

6
00:00:33,740 --> 00:00:34,310
Right.

7
00:00:34,700 --> 00:00:38,510
So this is done for scalability and of course, security.

8
00:00:39,240 --> 00:00:45,000
Okay, so we're the system administrators in Company X and ready to build.

9
00:00:45,510 --> 00:00:52,740
We have decided to use 192.168. x dot x as the private IP address space for our company.

10
00:00:53,600 --> 00:00:55,610
If we use the natural mask.

11
00:00:55,640 --> 00:00:59,000
255.255.0.0.

12
00:00:59,150 --> 00:01:03,440
That means we use the first 16 bits for network ID.

13
00:01:04,780 --> 00:01:06,940
And we'll have a single network.

14
00:01:07,720 --> 00:01:13,270
So in this case, we can address 65,536 devices in this network.

15
00:01:14,180 --> 00:01:17,840
Of course, the first IP and the last IP were not allowed to use.

16
00:01:17,840 --> 00:01:23,270
So the number of IP addresses actually 65,536 minus two.

17
00:01:23,300 --> 00:01:29,510
You do the math, but in practice, for ease of use, it's pretty much used as the power of two.

18
00:01:30,450 --> 00:01:40,830
So you can use an IP address in this network from 192.168.0. 1 to 1 92.168.255.254.

19
00:01:41,800 --> 00:01:48,250
But we need to have different networks, one for the managers, one for the developers, one for the

20
00:01:48,250 --> 00:01:49,460
servers, etcetera.

21
00:01:49,480 --> 00:01:56,260
So for the sake of our use and our sanity, let's use the next eight bits for subnets.

22
00:01:57,190 --> 00:02:02,740
In this case, we have a subnet mask of 255.255.255.0.

23
00:02:03,490 --> 00:02:08,199
Eight bits for subnet and 24 bits for the network ID in total.

24
00:02:08,560 --> 00:02:12,610
Eight bits left for dressing the devices under the subnets.

25
00:02:12,850 --> 00:02:14,110
So as a result.

26
00:02:14,840 --> 00:02:17,600
We can create 256 subnets.

27
00:02:18,200 --> 00:02:21,920
And address 256 devices for each one.

28
00:02:22,960 --> 00:02:29,470
Now we have 256 address ranges for 256 Subnetworks.

29
00:02:30,470 --> 00:02:34,430
So the table here shows a few examples of our potential subnetworks.

30
00:02:35,040 --> 00:02:40,770
The red colored blocks are added to the network ID as subnet identifiers.

31
00:02:41,160 --> 00:02:44,940
The rest of the eight bits are used as the host IDs.

32
00:02:46,000 --> 00:02:48,250
In the four block decimal notation.

33
00:02:48,490 --> 00:02:55,800
The third block identifies a subnetwork and the last block identifies the host.

34
00:02:55,870 --> 00:02:59,350
So breaking it down, It's much simpler now, isn't it?

35
00:02:59,740 --> 00:03:00,280
Excellent.

36
00:03:00,280 --> 00:03:01,060
Let's move on.