Prakash World's

Creating Workgroup Network 1.Set valid IP addresses for all computers in the network.Every computer must have same Network ID and unique host ID. 2. We need to set same work group name for all computers.This name identifies the network and its computers. Steps: A. Open My computer properties  B. Select computer name tab C. Click on change  D. Give a name for the computer  and select workgroup and type a workgroup name                ->OK E. In welcome message click OK   -> restart the computer 3.Next we need to configure the local security policy for all computers to allow network access.(disabled by default )      A.  Open Control Panel ->Administrative Tools ->Local Security Policy B. Expand local policies -> Select security option C. From right side list open and set the following options:                1. Network acc...

Setting IP Address 1. Open properties of My Network Places 2. Open properties of Local Area Connection 3.From the given list select Internet Protocol          Click on Properties  4. Select option use the following IP Address          Enter required IP address (192.168.100.1)           Select SubNet Mask (it will be auto set)           Click OK 5. Tick on show icon in notification area            Close          Setting IP Address from DOS 1. Go to CMD ( command com) in search program and files 2.  Type netsh(Enter) 3.Type interface (Enter)  4. Type ip (Enter) 5.add_address_"local_area_connection"_192.168.100.10_255.255.255.0 OK [show] Ping command This can be use...

  MAC Address (Media Access Control) This is also known as Physical address and hardware address. MAC address allows network cards to be able to send and recive data within the network. The MAC address is a unique 6 byte address stored in the ROM of network card. All companies that manufacture network cards need to first register with IEEE. The 6 byte address is divided into 2 parts; first 3 bytes is given by IEEE and is unique for each manufacturer, the other 3 bytes is set uniquely to each interface card that the company produces.     Protocols This is the software used for network communication which allows operating system to communicate with each other. Different types of operating system can also communicate if they use common protocol. Protocols are considered as the language used by operating system to communicate with each other. There are many types of operating system such as  TCP/IP-  Transmission Control Protocol / Intern...

Network Devices 1. Network card/ Adapters All computers must be installed with at least one network adapter. Network adapters come according to speeds such as 10/100 and 100/1000  Also we require separate network adapters according to type of cable. 2. Repeaters These are the devices used to extend the maximum distances of cables. It takes weak signals and strengths it so that it can travel more distance. Repeaters are two parts devices that can only extends a single connection. 2. HUB This the central device used in STAR devices. It provides the interface through which multiple computers can communicate with each other. This device also come according to speed and number of parts. We need separate HUBs according to type of cable. 4. Bridge This is the device used to interconnect two network segments together.  It can remember the physical address of all computers and perform. 5. Switch traffic filtering between segements to reduc...

  Network Cables There are three types of cables available . 1. Coaxial cable RG-8 (Thick Net) Mainly used in BUS networks. Thicknet cables had a thick outer coating which made it difficult to handle and it used the AUI connector (Vampire Tap) It has a speed of  10 mbps and  support upto 100 nodes. RG-58 (Thin Net) This has a thinner coating which made it easier to handle. It use the BNC connector. It has a speed of 10mbps and support upto 30 computers. 2. Twisted pair cable There are two types: I.UTP  II.STP This is used in STAR network. Twisted Pair cable came in different categories and each categories has a different speed and number of pairs. Name                          Speed                    ...

  Logical Topology Logical Bus This is  the commonly used logical topoology in LAN. In logical bus when one computer sends a message it can be seen by all  computer but only the destination computer will use it. We can identify a logical bus if we can send at any time. Logical Ring This is used in Token Ring network which uses a central device called MSAU ( Multi-Station Access Unit) In this network only one computer can send at a time while other computer will need to wait in queue. A special software called Token is available which is passed among all computers in the network only the computer with token can send. We can identify a logical ring if all computers have separate connections for sending and receiving.   Cellular Topology (wireless) This is the same as  Logical Bus. When one computer sends a message it can be seen by all computer but only destination computer will use it but there is no physical connection...

TOPOLOGY It defines the shape of network (logical /physical). Physical topology defines the physical connection used. Logical  topology defines how communication occurs in the network. Physical Topology Bus Topology Specifications: Speed: 10 mbps Number of computers: 30/100 Cables: ThinNet / ThickNet (coaxial cable) Connectors: BNC /AUI In this network all computers are directly connected to the central cable bus. This bus is the shared communication media for all network devices. Advantage: It is cheap and affordable.   Disadvantage: Speed is very low. Number of computer is low. In case of the cable failure entire network will fail. Difficult to pin point area of failure. Ring Topology Specification: Speed: 10 mbs Computer: 30/ 100 Cable: ThinNet/ ThickNet  Connector: BNC/AUI In thus network the first computer is connected to second, then second and third, and final computer is connected back to first f...

TYPES OF LAN MODELS Two types of LAN models are there:  1. Workgroup  2. Domain  1.Work group Network (Peer to Peer Network) This is simplest form of network. Mainly used in small offices and cybers. Perfect for up to 10 computers.  Advantages: Easier to  create the network as number of setting is less. Mainly used for internet connection sharing. Resource sharing is also easier to establish. Disadvantage: Security permission are difficult to apply on resources. User account cannot be controlled by a central location. There is no centralization. 2. Domain Network (Server /Client) This is the advanced form of networking used in large networks. This involves a main computer called DOMAIN CONTROLLER (server) and all other computer are its clients. This mainly provides security and centralization. Advantages: Almost all tasks can be performed from a central loaction.( Domain controller) All domain objects ...

NETWORKING Networking:   Two or more computers connected together and sharing resources. What is resource ? Any type of software or hardware that can be shared within a network. TYPES OF RESOURCES 1. Folder/ File 2. Disk drives 3. Printers 4.Scanner 5.Optical drive 6.Windows Desktop 7.Cameras   What is its advantage ? It allows us to access remote resource as if it were a local resource.   TYPES OF NETWORK CONNECTIONS: LAN:(Local Area Network) This is a network limited to a fix region such as single office or single building. All other networks are extension of LAN. MAN: ( Metropolitan Area Network) This is the interconnection of two or more LAN networks located far away, it is limited within a city. WAN: ( Wide Area Network) This is the interconnection of two or more LAN's located in distant region.   INTERNET: This can be referred as a WAN network. This uses the www. to communicate between ...

This is the basic equation of cosmology, and its solution tells how universe will evolve on large scales. We can derive it using Newtonian approximation, if we accept two results from General Relativity: First, there is, so called, Birkhoff's ,theorem, which says that, for a spherically symmetric system, the force due to gravity at some radius is determined only   by the mass interior to this radius. And also, the energy contributes to gravitational mass density. So we need to add them up together. Imagine a sphere with a mean density of row, radius of R, acceleration to a particle in surface, which is the second derivative of the radius, is given by formula.                 Ȑ = - 4 л G ϱ R                          3 Now, if the density changes, it c...

The beginning of the universe started with the cosmic background , which gets us back to the stage when the universe was 380,000 years old . Then, original chemical elements, found that helium had been formed when the universe was only three minutes old . Than dark matter got us further back when the time of the universe was like a ten billionth of a second , and Higgs boson frozen into the universe when it was only like a trillionth of a second . Antimatter , if this idea with the neutrinos would work out, gets us back to the very beginning, right after the inflation, we don't know exactly what the time scale is. the inflation itself when the for the structure we see today, that led to the formation of stars and galaxies , that right at inflation , and that's as far as we can get back to the beginning of the universe right now. Now we'll switch our gears to think about the future of the universe. And that's one of the really basic questi...