As the title says this article will have sequels preferring Mac Os x tips and tricks and some little facts. First of all let us see how to create an .iso image in mac using Terminal.app. You can create .iso image of files and folders.

Creating .iso Image File:

1. Goto Machintosh HD>Users>Application>Utilities>Terminal.app, double-click to open, the application will appear on your dock, bouncing.

2. Consider you have a folder named hpboddunan and its in your Desktop, first of all direct the Terminal command line to your desktop, to do that simply type "cd /Users/Boddunan/Desktop"

3. Now your Terminal command line will look like this: Boddunan:~ boddunan$

4. Type the following hard disk utility command :

Boddunan:~ boddunan$ hdiutil makehybrid -o hpboddunan.iso hpboddunan

5. Now your required .iso image of the folder hpboddunan is created on your desktop now you can mount the image using Disk Utility application located in your Utilities folder or simply double-click the file.

Mounting And Unmounting Volumes:

Consider you've a mac os and windows os for some reasons you wanna unmount the windows os Volume from your mac os, here is how we do it:

As on my system, to Unmount:

Anand:~ anand$ diskutil umount /dev/disk0s3
Volume /dev/disk0s3 Unmounted
Anand:~ anand$

disk0s3 means your windows os volume partition, by default your mac partition is disk0s2 and other partitions have next order like windows has disk0s3 in my system.

To Mount Again:

Anand:~ anand$ diskutil mount /dev/disk0s3
Volume /dev/disk0s3 mounted
Anand:~ anand$

That's all about mounting and unmounting.

How To Make Your Mac Read/Write a NTFS partition Disk:

NTFS means New Technology File System, well you have to google NTFS for more info as I'm not such a good expert in that, sorry!. Recently i found out that my windows partition is  NTFS which means as a mac user working from Mac Os you cannot Write a file to your windows Partition but you can read, only. So i tried out some solutions the best solution i found was a software that would make you read/write to your windows NTFS partition, the software is:

1. Paragon NTFS

2.Google for Paragon NTFS download and install

3. Restart your system.

4. Now your windows partition may seem unmounted so use terminal command to re-mount your windows NTFS partition.

5. Now you can both read/write your windows NTFS partition.

6. One extra-benefit is that you can not only read/write Windows NTFS partition but any external NTFS formatted Hard Disk.

This is a really good tip.

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