Difference Between Hub,Switch and Router

Hub


A common connection point for devices in a network. Hubs are commonly used to connect segments of a LAN. A hub contains multiple ports. When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.



There are three main points to remember about hubs:

• Many kinds of nodes can be connected to the hub with networking cable.
• All hubs can be uplinked together, either with straight-through cable or cross-over cable, depending on whether or not the hub has an uplink port.
• Performance will decrease as the number of users is increased.

When choosing a hub, the main consideration should be performance. If the hub is 100Mbps and there are five users, each user will receive only 20Mbps of bandwidth. If the hub is intended for a small network with very little traffic, this should not be a problem. However, if the network is large or expected to expand, a switch is a better option in the end.
When considering a hub, always remember that the network may expand in the future. Try to buy a hub that has enough ports to allow expansion without more hardware purchases. If expansion is not an immediate concern, remember that in the future you can add more hubs.
The standard hub is great for starting a small network, or providing a network to one department. There are two basic types: 10baseT, which will support a speed of 10Mbps; and 100baseTX, which supports 100Mbps. A standard 10baseT hub cannot connect to hardware that runs at 100Mbps unless a switch or hub with auto-sensing capabilities is used between them. If your network is small and will not require expansion in the near future, a standard hub is the perfect solution.


Switch


In networks, a device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) and sometimes the network layer(layer 3) of the OSI Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs.

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Switches also run in full duplex mode, which allows data to be sent and received across the network at the same time. Switches effectively double the speed of the network when compared to hubs, which only support half duplex mode.
A 10/100Mbps switch can also support hardware running at either 10Mbps or 100Mbps, allowing the continued use of older technology and delaying replacement.
Switches will increase the speed and efficiency of networks in any of the following situations:

• Any network that calls for a 10/100 hub will benefit from a 10/100Mbps switch. The switch will increase available bandwidth, drastically increasing the speed that the network is running at.
• Any network that requires enhanced performance for file servers, workstations, Web servers, etc. Any critical components should be connected directly to a 10/100Mbps switch.
• Any network that uses high-speed applications including multimedia and video. Any workstation or file server using the intensive applications should be connected directly to a 10/100Mbps switch.
• Any network that uses Fiber optic cabling should use a 10/100Mbps switch rather than a hub. A hub will not take full advantage of the speed possible with Fiber optic cabling.

Router


A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP.s network. Routers are located at gateways, the places where two or more networks connect. Routers use headers and forwarding tables to determine the best path for forwarding the packets, and they use protocols such as ICMP to communicate with each other and configure the best route between any two hosts

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What is DNS, and its Working?

Introduction

A key component of the Internet and how it works revolves around the Domain Name System, otherwise known as DNS. The underlying technology behind the Internet, is that when a computer needs to talk to another computer on the Internet, they communicate via the computer's IP Address. The IP Address is a unique set of numbers associated with a particular machine, which will be discussed in a separate article. An example of an IP Address is 216.213.19.27, which is the IP Address that corresponds to www.pcprompt.net.

As the predecessor of the Internet, ARPANET, grew larger, connecting to remote machines by their IP Address grew cumbersome. It became more and more difficult for people to remember the IP Addresses associated with the machines they were trying to reach that a system was created to translate easier to remember symbolic names to their equivalent numerical IP Address. Thus the Domain Name System was born.

Domain Name System

The Domain Name System is the system used on the Internet for the mapping of names, such as www.google.com, to IP Addresses such as 216.239.51.99. Every time a new domain, like pcprompt.net, is registered, that domain is entered into one of the 13 Root Servers spread throughout the world and overseen by an organization called ICANN. Because your domain is in one of these servers, it can be reached and understood by the rest of the users on the Internet.

Another key element of the Domain Name System are DNS Servers run by Companies and Internet Service Providers. Every time you connect to a site, you are asking your ISP's DNS Server to resolve, or convert, the hostname such as www.google.com to a an ip address such as 216.239.51.99. If your ISP's name server is not working or can not be reached, then you will not be able to traverse the Internet using hostnames, but instead would have to use their IP Address equivalent.

Any time you connect to a site, your ISP DNS Server must find out what name server has the information about the domain for the site you are trying to reach. Your ISP's DNS Server will connect to a Root Server and ask it who the name server is that knows the information about the site you are trying to reach. The Root Server will tell your ISP's DNS Server what server they should next contact for information. Next your ISP's DNS Server will then contact the server that the Root Server told it to contact, where it will be given the IP Address associated with the site you are trying to reach.

Real Life Example

A lot of what has been discussed may be a bit confusing, so lets do a real life example. In the flowchart below labeled Figure 1, you will see a computer trying to connect to www.google.com and the steps it takes.

We will discuss these steps below:

1. A User opens a web browser and tries to connect to www.google.com. The operating system not knowing the IP Address for www.google.com, asks the ISP's DNS Server for this information.
2. The ISP's DNS Server does not know this information, so it connects to a Root Server to find out what name server, running somewhere in the world, know the information about google.com.
3. The Root Server tells the ISP's DNS Server to contact a particular name server that knows the information about google.com.
4. The ISP's DNS Server connects to Google's DNS server and asks for the IP Address for www.google.com.
5. Google's DNS Server responds to the ISP's DNS server with the appropriate IP Address.
6. The ISP's DNS Server tells the User's operating system the IP Address for google.com.
7. The operating system tells the Web Browser the IP Address for www.google.com.
8. The web browser connects and starts communication with www.google.com.

Conclusion

As you can see, the Domain Name System is essential in the use of the Internet. Without it, you would not be able to type in names, but would have to remember the numerical IP Addresses in order to get anywhere on the Internet.

Reference: Internet

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How DHCP Works

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 install Windows8 step by step

To know Latest News about windows8: Click here

Download Windows8 Developer Preview iso image From Microsoft Website : Click Here

After download you can burn to a dvd...

For Making a Bootable USB Drive, download a simple tool From microsoft store : Click Here

After installing Select iso image 

 Select the media

select the USB drive which you want to convert into bootable Windows 8 drive and click Begin copying. The USB device must be larger than 4GB.

It will start copying the files and after some time your USB will be ready.

After above steps... Time for installation

Restart your Computer and change the boot device priority to USB Drive from BIOS

and Boot from USB Drive

after sometime you can see a window like below

To know Latest News about windows8: Click here

Select your language and click next

click install now, If you are already installed this windows 8 then you can repair with below option "Repair your computer"

This window indicates the license agreement

For upgrade your windows7 to windows8 then you can select upgrade option other wise you can click custom..
here we are selecting custom

To know Latest News about windows8: Click here

partition created by drive option displyed below the screen

How to create partition 

Installation  Process

Enter your user name here

Loading with your personal settings and Enjoy with windows 8

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New Features in Ubuntu 12.04

Finally Launched!!! Ubuntu 12.04
Ubuntu 12.04 LTS. Canonical's latest is now available in its final(ish) form and ready for you to download, burn and install. While LTS (Long Term Support) releases are generally more conservative in their application of new features, Pangolin does include some rather notable tweaks.

Some New Features in Ubuntu 12.04


The HUD

As hinted by Canonical founder Mark Shuttleworth in late January, Ubuntu's new “Head-Up Display,” or “HUD,” interface makes its debut in this beta version. Dubbed as “a new way to quickly search and access any desktop application’s and indicator’s menu,” HUD can be accessed by pressing the Alt key and typing in a description of what you want to do. The software will then return a set of corresponding entries, including some fuzzy matching, the project team says. Over time, it also learns from your previous choices to make the search more and more accurate, they note.

PRIVACY

The Zeitgeist engine has been integrated in Ubuntu since 11.04. It’s also known as the activity log — it logs things you do on your computer, including files you open, websites you visit, and people you have conversations with. These logs are stored locally and offered to other desktop applications, which can use them to customize your experience.
Responding to privacy concerns, Ubuntu now includes a Privacy panel for managing this behavior. You’ll find it in Ubuntu’s System Settings window.

The Privacy panel includes quite a few options for managing this behavior. In addition to disabling activity recording entirely, you can disable it for certain types of files, folders, or applications. You can also manually delete the activity history — either all of it, or just the history for a recent time period.


Unity Appearance Settings

Ubuntu's Unity interface has been nothing if not controversial, but in this new release, the "Appearance" panel in the software's system settings lets you more easily configure some properties of Unity. For bookmark users, the Unity launcher now also includes Nautilus quicklist support.

 On the Look tab, the size of the application icons on Unity’s launcher are now configurable — you can make them smaller or larger.

On the Behavior tab, you can customize when Unity automatically hides itself. It no longer automatically hides by default, but you can enable the auto-hide feature and tweak its sensitivity, if you like.

Quick Lists

Many more applications now support Unity’s “quicklists” feature, including the Nautilus file manager and Rhythmbox music player. Right-click an application icon on the Unity launcher and you’ll find shortcuts to frequently used options. For example, the Nautilus file manager displays your bookmarked locations, while the Rythmbox music player offers playback options.

Video Lense
Lenses allow you to perform different types of searches directly from Unity’s dash, and Precise Pangolin introduces a new lens for searching videos. Select the video icon at the bottom of the dash screen and you can search for videos stored locally or in a variety of online locations, including YouTube, Vimeo, and TED Talks. Use the Filter Results option to search for videos from a specific location.

 Software Recommendations

The Ubuntu Software Center now offers personalized software recommendations. Click the Turn On Recommendations button at the bottom of the Ubuntu Software Center to enable them. You’ll have to log in with your Ubuntu Software Center account — this is the same as your Ubuntu One or Launchpad account.
When you enable recommendations, your list of installed software will be periodically sent to Canonical’s servers. Recommendations will appear in the Ubuntu Software Center.

 Ubuntu one Redesign

Ubuntu One, Ubuntu’s cloud storage service, has a redesigned interface in Precise Pangolin. Interestingly enough, the new interface uses the QT toolkit (used in KDE). The QT-based interface replaces the old one, which used the same GTK+ toolkit used in GNOME, Unity, and elsewhere on the Ubuntu desktop.

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Windows8 Editions

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CLick Here to Read Related windows 8

Windows 8 Come with 3 flavors

windows 8
Windows 8 is the official product name for the next x86/64 editions of Windows.

Windows 8 Pro 

Windows 8 Pro is designed to help tech enthusiasts and business/technical professionals obtain a broader set of Windows 8 technologies. It includes all the features in Windows 8 plus features for encryption, virtualization, PC management and domain connectivity. Windows Media Center will be available as an economical “media pack” add-on to Windows 8 Pro. If you are an enthusiast or you want to use your PC in a business environment, you will want Windows 8 Pro

Click Here For Features of Windows8

Windows RT

is the newest member of the Windows family – also known as Windows on ARM or WOA, as we’ve referred to it previously. This single edition will only be available pre-installed on PCs and tablets powered by ARM processors and will help enable new thin and lightweight form factors with impressive battery life. Windows RT will include touch-optimized desktop versions of the new Microsoft Word, Excel, PowerPoint, and OneNote. For new apps, the focus for Windows RT is development on the new Windows runtime, or WinRT, which we unveiled in September and forms the foundation of a new generation of cloud-enabled, touch-enabled, web-connected apps of all kinds.

 CLick Here to Read Related windows 8

Application wise comparison chart :

Feature name	Windows 8	Windows 8 Pro	Windows RT
Upgrades from Windows 7 Starter, Home Basic, Home Premium	x	x
Upgrades from Windows 7 Professional, Ultimate		x
Start screen, Semantic Zoom, Live Tiles	x	x	x
Windows Store	x	x	x
Apps (Mail, Calendar, People, Messaging, Photos, SkyDrive, Reader, Music, Video)	x	x	x
Microsoft Office (Word, Excel, PowerPoint, OneNote)			x
Internet Explorer 10	x	x	x
Device encryption			x
Connected standby	x	x	x
Microsoft account	x	x	x
Desktop	x	x	x
Installation of x86/64 and desktop software	x	x
Updated Windows Explorer	x	x	x
Windows Defender	x	x	x
SmartScreen	x	x	x
Windows Update	x	x	x
Enhanced Task Manager	x	x	x
Switch languages on the fly (Language Packs)	x	x	x
Better multiple monitor support	x	x	x
Storage Spaces	x	x
Windows Media Player	x	x
Exchange ActiveSync	x	x	x
File history	x	x	x
ISO / VHD mount	x	x	x
Mobile broadband features	x	x	x
Picture password	x	x	x
Play To	x	x	x
Remote Desktop (client)	x	x	x
Reset and refresh your PC	x	x	x
Snap	x	x	x
Touch and Thumb keyboard	x	x	x
Trusted boot	x	x	x
VPN client	x	x	x
BitLocker and BitLocker To Go		x
Boot from VHD		x
Client Hyper-V		x
Domain Join		x
Encrypting File System		x
Group Policy		x
Remote Desktop (host)		x

CLick Here to Read Related windows 8

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what is 32 -Bit and 64 -Bit

whats the Difference between 32bit and 64bit

What is a Bit ?

In computing, a bit can be defined as a variable or computed quantity that can have only two possible values. These two values are often interpreted as binary digits and are usually denoted by the numerical digits 0 and 1. The two values can also be interpreted as logical values (true/false, yes/no), algebraic signs (+/−), activation states (on/off), or any other two-valued attribute.  OR  The amount of information that can be stored by a digital device or other physical system that can
usually exist in only two distinct states. These may be the two stable positions of an electrical switch, two distinct voltage or current levels allowed by a circuit, two distinct levels of light intensity, two directions of magnetization or polarization, etc. 

What is the difference between 32-bit and 64-bit versions of Windows? 

The terms 32-bit and 64-bit refer to the way a computer's CPU, handles information. The 64-bit version of Windows handles large amounts of random access memory (RAM) more effectively than a 32-bit system.

What are the Advantages of a 64bit Processor?

1. More greater performance then 32bit Processor.
2. Allowing for the addressing of more of RAM, 64-bit processing can improve video encoding and decoding, CAD, VMs and some other applications.
3. Ability to address memory amounts over four GB, and up to 16 exabytes

What are the Disadvantages of 64bit Processor?

1. You’re currently not able to take full advantage of the technology because the software vendors haven’t made the switch from 32-bit to 64-bit processors.
2. Most AMD Athlon 64 bit processors are expensive, with prices sure to go down in the future.

Note : You can Still use softwares built for 32bit processor but you cannot use 32bit drivers on 64bit processor
Here's a picture of software built for 32bit that works very well on 64bit , its a preview from task manager

32 bit software working in 64bit PC

All the software of 32bits are marked with a asterisk mark and 32 after it as you can see in the preview 

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