VLAN is intended to create a separate broadcast domain within a switch. Realize that switches break up collision domains, but not broadcast domains. So in order to divide a switch up in to separate broadcast domains you use VLAN's. A broadcast in VLAN 1 will not be heard in VLAN 2.

This is all at layer 2. We have not even introduced a router.

Subnets on the other hand are created to preserve IPv4 address space, and is obviously at layer 3.

Both of these provide a level of security. In the real world it is not seen as "one or the other". Often, or mostly, both are used. It's typical to throw a subnetted network in to it's own VLAN (in order that it only hears broadcasts intended for its network). You do not see people in the same subnet on seperate VLAN's (they need broadcasts), unless you start talking about private VLAN.

This is the kind of stuff I would encourage a CCNA to actually lab up. It's easy to lab in packet tracer. Just take a switch, toss 2 PC's on there. Configure PC100 in VLAN100, and PC200 in VLAN200. Put them both on 10.0.0.0 network. Then attach a router....and think about how you would get the two PC's to ping each other

Subnetting is basically breaking down a group of IP addresses in to smaller groups a way of managing IP addresses. With IPv4 we have a limited amount of IP adds that we can use so we have to manage them by subnetting

Let us consider this ip address

192.168.10.0

We all know ip address is made up of 4 octects...

we have seen similar ip addresses like

192.168.10.1 192.168.10.2.... 192.168.10.250 like that

Why there is no 192.168.10.256 or 192.168.10.300 or 300.1.5.258 ?

We all know ip addresses are represented in bit wise pattern

Ip address :- 32 bits (4 octets)

00000000.00000000.00000000.00000000
0. 0. 0. 0

11111111.1111111.11111111.1111111
255.255.255.255

So 0 is the minimum value
and 255 is the maximum value

Then in the case of a valid host..
For every network there should have to be a network id and broadcast id...
The first available ip address will be the network id and the last one will be the broadcast id

In this case...

192.168.10.0 :- The first available ip address

192.168.10.255 :- The last available ip address

First one will be the network id and the last one the broadcast id..

This rule is valid for every networks

Consider a case...

In your company you are in a situation like this...You have only one address pool or range ...Your boss asked you to create two networks from that pool...

So the real subnetting test begins...

Consider 192.168.10.0 is that range.....

In normal case

If we give an ip from the network 192.168.10.0
the default subnetmask will be 255.255.255.0


192.168.10.0
255.255.255.0 /24

No. of hosts = ?
For class c networks consider only the last octet of the subnetmask...

Last octet 0
Binary of 0 = 00000000
Then from that find the no. of networks and hosts

2 raised to no. of ones in that octet will be the no. of networks
2 raised to no. of zeros -2 will be the no. of hosts (explaination follows)

00000000
no.of ones :- 0 0*1= 1
no. of zeros :- 8 2*8-2 = 256-2 = 254


So the network range


192.168.10.0
192.168.10.1

192.168.10.253
192.168.10.254
10.192.168.10.255

So as per our rules

192.168.10.0 --- Network id

192.168.10.1 ----First available host

192.168.10.254 ----Last available host

192.168.10.255 ----- Last host

We have network 100.0.0.0 with Subnetmask 255.255.255.240.
We want to create an ACL for this network. THis WHOLE network should be denied something.
For the acl, we need the proper Wildcard Mask for that Subnet.


The Subnetmask is binary

11111111.11111111.11111111.11110000=255.255.255.240

For Wildcard Masks, only the ZEROS are interesting.
So make a simple addition (watch the last oktett!)

8+4+2+1=15

So the wildcard mask will be

0.0.0.15

Tips to run computer fast for long time:

By following the given tips you can avoid problems in your computer before problems occurs.

* Do scan disk for every week:

By this method the errors in the computer are detected and cleaned by the operating system.

* Install Genuine anti virus software with update. Discuss with Software Engineers to get a Genuine Anti Virus Software and install it in your system.

* Do Virus scan often to avoid spreading virus in your computer.

* Some Anti Virus software are available on internet for free. But be care full when downloading that type of software. Because there is lots of free anti virus software comes with virus.

* Do Install Firewall:

If you are using internet, you should install firewall in your system. The Firewall stops the unwanted program which is called ‘ad ware’ and ‘spy ware’. You can do on these firewall settings by going to Start=>programs=>accessories=>system tools=>security centre.

* Defrag your system every month:

Defragment arranges the fragmented files on hard disk. When you install or uninstall some files, program files in the hard disk are fragmented. Then the system will be slow down. By defragmenting you can increase your system speed and can avoid unwanted programs.

* Clean your hard disk drives every week:

To increase Performance of your computer you should cleanup your hard disk for every weak. This disk cleanup removes the remaining unwanted files which are stayed in hard disk after uninstalling a program.

* Avoid unwanted downloading from internet:

We are all downloading lot of files from internet. There are lots of freeware programs in the internet. Some freeware programs come with virus. Hence, you should aware when downloading like that freeware programs. So, you should avoid maximum downloads.

* Remove the unwanted programs:

When a program is not used for long time you can remove that program by using Add/remove programs. By doing this there will increase disk space in your hard disk. The computer performance speed will also increase.

*Clean up your computer from dust for every week.

* After following the above, your computer will perform faster than ever.