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Super computer made from cluster of Apple G5′s

January 31, 2008


Video: Google Video

This video shows a cluster of 1100 Apple G5 computers at Virgina Tech. It is the 3rd most powerful super computer in the world and the least expensive system in the top 10.

The basics of using the ping program

December 18, 2007

So some of you may have heard your local technician or your IT administrator at work use the term ‘Ping’. So whats it mean and how can you use it.

Firstly ping is a small program that runs in DOS or a command prompt from Windows or from a command line interface in Linux or Unix.

Ping when used allows you to send a small message to another device on your network or on a remote network such as the internet. You are sending this message to the devices IP Address. (each network device has an address called its IP address) See my previous post on IP Addresses

If your network is working properly you should be able to receive a reply from the machine that you sent the message to, this will then tell you that your connection to that remote device is intact.

So when will the ping program be useful, well lets say for instance you go to access your broadband internet and it doesn’t appear to work, you open your browser and your internet site does not display. The ping program can tell you if you have access to your broadband modem and also tell you if you can ping the outside world (internet).

OK so how do we use the ping program. In Windows we need to open a command prompt. To do this for Windows XP and Vista you will need to go to the start button and choose run and then type cmd and then press OK or enter. For windows 98 or millenium you will need to go to start and run and type command and then press OK or enter. (See picture below)

Run Command
Run Command

So once you hit OK you will see a command prompt box appear as in the picture below

Command Prompt
Command Prompt

So now we need to ping one or two things to see if we have access or not. So what ip address or addresses do we ping.

In the command prompt above I have typed ipconfig, this command will give you your ip address, default gateway and subnet mask as shown in the image below.

Ipconfig
Ipconfig

So it is the default gateway on your PC that I would like you to ping first. So I’m going to type ping 192.168.1.1 and you will need to replace the 192.168.1.1 with whatever your IP address is, so the command is;

ping 192.168.1.1

You should see 4 replies if you are connected to your broadband modem as in the image below. If you receive the replies from your default gateway the next step is to ping an Ip address from the internet and then finally a domain name on the internet. In the sample below I have pinged yahoo.com’s ip address and then their domain name.

So it’s ping 216.109.112.135 and then ping yahoo.com.

Using the ping command
Pinging IP address

So to wrap up, we have learnt

1. How to find find our own ip address and default gateway.

2. The usefulness of the ping command to see if we are connected to our broadband modem and or the internet.

3. How to ping our default gateway and a device on the internet such as yahoo.com’s servers.

Basic Networking: The IP Address

December 17, 2007

So what’s this IP address thing that you sometimes here the techy’s talking about.

For the purpose of this tutorial we will look at IP Addresses using IP Version 4 as this is currently the most widely used and IP Version 6 is still not widely used.

An IP address is basically a set of unique numbers that electronic devices use to identify and communicate with each other on a network such as the internet or a local network like you would see in an office environment.

The concept is very similar to the house where you live having an address, ie your name might be Mr Jones and your address 99 Main Street, Denver, Colorado USA. Therefore if I was to send a letter by post to you I would need to fill out the full details as below.

Mr Jones
99 Main Street
Denver, Colorado
USA

In Networking the IP addresses look like this sample below,

192.168.1.1 or 203.12.160.35

Some IP addresses are meant to be unique on the Global Internet, while others only need to be unique within your local Network.

So for every device that is directly connected to the internet it will need a unique address that sets it apart from every other device on the internet.

Examples of these devices are your broadband router or modem that connects you to the internet, Internet web servers such as www.google.com etc.

So what about if you have a broadband modem at home and you have one or two or more computers connected to this modem and they all access the Internet.

Well what happens in this situation is, the modem gets a unique IP address for the internet and any of the computers that connect to that modem and then access the internet will get there own address that is only unique for your local little network at home. Any of the computers that use the internet will use the address of the modem to access the internet.

Please see how this works in the picture below.

Ip Address
Picture: The Wizard

Please note this is a part of the basic networking series, we will soon be beginning a more advanced networking series for those of you interested. Stay tuned!

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