How Search Engines Works

17 July, 2012

What is search Engine?
Basically, a search engine is a software program that searches for sites based on the words that you designate as search terms. Search engines look through their own databases of information in order to find what it is that you are looking for.
When people use the term search engine in relation to the Web, they are usually referring to the actual search forms that searches through databases of HTML documents, initially gathered by a robot.

There are basically three types of search engines: 

1. powered by robots (called crawlers; ants or spiders)
2. powered by human submissions
3. hybrid of above two

Crawler-based search engines are those that use automated software agents (called crawlers) that visit a Web site, read the information on the actual site, read the site's meta tags and also follow the links that the site connects to performing indexing on all linked Web sites as well. The crawler returns all that information back to a central depository, where the data is indexed. The crawler will periodically return to the sites to check for any information that has changed. The frequency with which this happens is determined by the administrators of the search engine.

Human-powered search engines rely on humans to submit information that is subsequently indexed and catalogued. Only information that is submitted is put into the index.

Popular Search Engines:

google

bing

yahoo

blekko

yebol 

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How DHCP Works

17 May, 2012

Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway. RFCs 2131 and 2132 define DHCP as an Internet Engineering Task Force (IETF) standard based on Bootstrap Protocol (BOOTP), a protocol with which DHCP shares many implementation details. DHCP allows hosts to obtain necessary TCP/IP configuration information from a DHCP server.

Benefits of DHCP

• Reliable IP Address configuration
• Reduced Network Administration

How DHCP Works

1.DHCP DISCOVER: The Dynamic Host Configuration Protocol (DHCP) client broadcasts a DHCP discover message on the network containing its MAC address and NetBIOS destined for UDP port 68 (used by BOOTP and Dynamic Host Configuration Protocol (DHCP) servers). This first datagram is known as a DHCPDISCOVER message, which is a request to any DHCP server that receives the datagram for configuration information.

2.DHCP OFFER: Each DHCP server on the network that receives the request responds with a DHCP offer message as broadcast (UDP port 67) to the computer that issued the DHCPDISCOVER. An offered the IP address and subnet mask is also included in the message. If the DHCP client device received multiple DHCPOFFER, the DHCP client accepts the first DHCP offer that arrives.

3.DHCP REQUEST: The Dynamic Host Configuration Protocol (DHCP) client accepts an offer and broadcasts a DHCPREQUEST datagram. The DHCPREQUEST datagram contains the IP address of the server that issued the offer and the physical address of the DHCP client. DHCPREQUEST message requests the selected DHCP server to assign the DHCP client an IP address and other TCP/IP configuration settings. DHCPREQUEST message also notifies all other DHCP servers that their offers were not accepted by the DHCP client.

4.DHCP ACK: When the DHCP server from which the offer was selected receives the DHCPREQUEST datagram, it constructs a DHCPACK datagram. This datagram is known as a DHCPACK (DHCP ACKNOWLEDGEMENT). The DHCPACK includes an IP address and subnet mask for the DHCP client. It may include other TCP/IP configuration information like IP addresses for the default gateway, IP addresses for DNS servers, IP addresses for WINS servers etc.

DHCP Terms and Definitions

Term	Definition
DHCP server	A computer running the DHCP Server service that holds information about available IP addresses and related configuration information as defined by the DHCP administrator and responds to requests from DHCP clients.
DHCP client	A computer that gets its IP configuration information by using DHCP.
Scope	A range of IP addresses that are available to be leased to DHCP clients by the DHCP Server service.
Lease	The length of time for which a DHCP client can use a DHCP-assigned IP address configuration.
Reservation	A specific IP address within a scope permanently set aside for leased use by a specific DHCP client. Client reservations are made in the DHCP database using the DHCP snap-in and are based on a unique client device identifier for each reserved entry.
Exclusionrange	One or more IP addresses within a DHCP scope that are not allocated by the DHCP Server service. Exclusions ensure that the specified IP addresses will not be offered to clients by the DHCP server as part of the general address pool.
APIPA	A TCP/IP feature in Windows XP and Windows Server 2003 that automatically configures a unique IP address from the range 169.254.0.1 through 169.254.255.254 with a subnet mask of 255.255.0.0 when the TCP/IP protocol is configured for automatic addressing, the Automatic private IP address alternate configuration setting is selected, and a DHCP server is not available. The APIPA range of IP addresses is reserved by the Internet Assigned Numbers Authority (IANA) for use on a single subnet, and IP addresses within this range are not used on the Internet.
Superscope	A configuration that allows a DHCP server to provide leases from more than one scope to clients on a single physical network segment.
Multicast IP	Multicast IP addresses allow multiple clients to receive data that is sent to a single IP address, enabling point-to-multipoint communication. This type of transmission is often used for streaming media transmissions, such as video conferencing.
Multicast Scope	A range of multicast IP addresses that can be assigned to DHCP clients. A multicast scope allows dynamic allocation of multicast IP addresses for use on the network by using the MADCAP protocol, as defined in RFC 2730.
BOOTP	An older protocol with similar functionality; DHCP is based on BOOTP. BOOTP is an established protocol standard used for configuring IP hosts. BOOTP was originally designed to enable boot configuration for diskless workstations. Most DHCP servers, including those running Windows Server 2003, can be configured to respond to both BOOTP requests and DHCP requests.

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How to Use Remote desktop in Windows 7

20 January, 2012

 
The Remote Desktop(RDP) utility lets you connect to your work computer from home and access all of your programs, files, and network resources as though you were actually sitting in front of your own computer. Creating the remote desktop connection in Windows 7 is almost the same as in the older versions of Windows. This post will cover the following
things:

1. How to enable the remote desktop connection feature on a Windows 7 machine
2. How to Remotely connect any other Windows based machine from Windows 7

How To Enable Remote Desktop in Windows 7

First click the Start button on your desktop, now right click the Computer option from the start menu and select its properties.

 

Then click the Remote settings option in the next window.

Now make sure to enable the option Allow connections from computers running any version of Remote Desktop in the System Properties dialogue box.

Click Apply and the remote desktop connections feature will be enabled on your Windows 7 machine.

How To Establish A Remote Desktop Connection From Windows 7

Firs of all click Start > All Programs > Accessories > Remote Desktop Connection link.

The Remote Desktop dialogue box will be displayed, here specify the IP address of the remote machine to which you are going to connect.

Click Here to know about IP Address

Click the Connect button, now it will try to access your specified machine and if the machine is running and remote connections are enabled on it, then it will prompt for the username and password of that machine. I accessed my XP machine from Windows 7 via remote desktop.

 

Done!!!

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How to Setup Voice Recognition in Windows 7

15 January, 2012

Speech Recognition technology allows you to control your computer by speaking. When you talk, the software will intelligently decide whether to convert your voice into text, such as to allow you to dictate documents and e-mails, or whether you have given a command that requires it to take an action.

How to Setting Up in WIndows 7

1. Plug-in your microphone.
2. Click Start
3. Search for “speech recognition” and click on Windows Speech Recognition
4. If this is your first time using Speech Recognition (it likely is, since you’re reading this), a Microphone Setup Wizard will pop-up, asking you to do some stuff

 

1.  Follow the instructions, and after your microphone is set up.
   
   Warning: This might take 15 mins – 30 mins. But if you’re new to this, don’t worry, Windows will walk you though.
2. Try to pay attention during the tutorial, it’ll tell you everything you need to use Window’s Inbuilt Features
3. After you’re done the tutorial, just click the microphone on the Windows Speech Recognition Bar, and watch the Microphone button glow blue. Now you’re ready to speak… to your computer!

That’s all there is to it. A few words of caution though:

• Dictating to your computer might sound easy, but you’re computer certainly isn’t a human, and chances are that it will only understand you most of the time, missing difficult to interpret words.
• Be careful when you are talking to someone else and your microphone is turned on.
I find that composing your dictation in a program such as Wordpad or Microsoft Word is better than composing in a program like outlook or in a web browser.  You can compose things in Wordpad and then just copy and paste them wherever you want.
• Make sure you use the correct command instead of typing things on your own, windows learn from it and become better.

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How to Create a System Image in Windows 7

10 January, 2012

We can take a backup image of our machine without the need for a third party utility like Ghost or True Image. You just just finished installing a fresh copy of Windows 7 on your computer and have it set up to your liking. One of the first things you should do now is create an image of the disc so in the event of a crash you will be able to restore it to its current state. An image is an exact copy of everything on the drive and will restore it back to its current state. It’s probably best to create an image when everything is clean and organized on your system.

This will make the image file smaller and allows you to restore the system with a smooth running set up.

Creating an Image in Windows 7

Click on Start go to Getting Started and then select Back up your files. 

Next click on the Create a system image hyperlink.

Decide where you want to save the image. You can choose an external drive, burn to multiple DVD’s, or store it on a network location.

You can include other drives if you want as well but remember that will add to the size of the final image.

At the confirmation screen notice the amount of space the image may take. If something doesn’t look right you can still go back from this point and make adjustments.

A progress meter is displayed while the images is created and backed up. In this example a disk of about 15GB in size took under 20 minutes backed up to an external drive. Times will vary depending on your system and where you’re backing it up to.

After the process is complete you get the option to create a system repair disc which you should do and make sure to save it in a secure location.

 

When it comes time to restore the image, you will be able to use the System Recovery Options to get the system back.

Reference Link: Click Here

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