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      Technical Questions

    What is a computer?

    A computer is an electronic device through which we can save data and retrieve data.It is

    commonly known as the Arithmetical Logical Unit.

    What is a USB cable?

    USB cable is a device used to connect external devices to the computer, e.g., printers, scanners

    etc.

    What is Server?

    In information technology, a server is a computer program that provides services to

    other computer programs (and their users) in the same or other computers. The

    computer that a server program runs in is also frequently referred to as a server (though

    it may be used for other purposes as well).

    What is BIOS?

    BIOS (basic input/output system) is the program a personal computer's microprocessor

    uses to get the computer system started after you turn it on. It also manages data flow

    between the computer's operating system and attached devices such as the hard disk,

    video adapter, keyboard, mouse, and printer.

    What is a USB Hub?

    A USB HUB is a port through which we can connect multiple USB devices to the computer at

    the same time.

    What is a motherboard?

    It is the main circuit board of a computer. Also known as main board/system board.

    What is RAM?

    RAM (random access memory) is the place in a computer where the operating system,

    application programs, and data in current use are kept so that they can be quickly

    reached by the computer's processor. RAM is much faster to read from and write to

    than the other kinds of storage in a computer, the hard disk, floppy disk, and CDROM.

    However, the data in RAM stays there only as long as your computer is running. When

    you turn the computer off, RAM loses its data. When you turn your computer on again,your operating system and other files are once again loaded into RAM, usually from

    your hard disk.

    What is ROM?

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    Common security attacks and their countermeasures

     

    Finding a way into the network 

    Firewalls

      Exploiting software bugs, buffer overflows  - Intrusion Detection Systems

      TCP hijacking

      - IPSec

      Packet sniffing

      - Encryption

      Social problems

      - Education

    What is intranet?

    Intranet is a secured and private communication between the network of computer's.

    Domain Naming

      Domain Name (example. Microsoft.com)

      Top -level domain (com)

     

    Second-level domain (microsoft.com)

      Subdomain (example. Microsoft.com)

    What is CD-ROM?CD-ROM is a device used to read the data saved on the CD.

    What is a CD-Writer?

    CD-Writer is used to read and write the data to and from the CD.

    What is a sound card?

    A sound card is a device inbuild on the motherboard.It helps in the output of sound to the audio

    devices and input of sound from the microphone.

    What is a Video Capture Card?

    It is placed inside a computer case,used to put video into a computer,requires a video

    source,either a video camera/video recorder.

    What is a CPU?

    It is the central processing unit.It determines the processing power of the computer.Does all of

    the mathematics, mainly addition. Does all the logical comparisons of values .Directs the flow

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    of data in a computer .Controls the operation of the parts of the computer.The speed of CPUs is

    measured in hertzs.Most computers have a CPU that can do more than 400 Mhz. CPU is a brain

    of a computer, consisiting of

    Arithmetic and logic unit (ALU): performs arithmetic calculations (addition, subtraction...) and

    logical decisions.

    Control Unit (CU): decodes each machine instruction and sends signal to other components for

    carrying out the instruction.

    An integrated circuit (IC) that is a full central processing unit is called a microprocessor.

    CPU speed : (M: Mega = 10^6, Hz= 1/sec);

    What is a Memory?

    A large collections of circuits, each capable of storing bit

    Cells(words): manageable units; typical size is 8 bits (1byte), some machines are 16 bits(2byte)

    and some

    are 32bits or 64 bits

    Byte (8 bits)

    KB(kilobyte, 10^3=2^10bytes)MB (Megabyte, 10^6 = 2^20bytes)

    GB (Gigabyte, 10^9 = 2^30bytes)

      Computer memory is comparable to a collection of numbered mailboxes. To identify individual

    cells in a machine's main memory, each cell is assigned a unique name, called its address

    The organization of byte-size memory cell

    Most Significant Bit(MSB) Least Significant Bit(LSB)

    Roles of Computers in a Network

    Database Server

    Mail Server

    Fax Server

    File and Print Server

    Directory Services Server

      What are expansion slots?

    Expansions slots appear on the motherboard.They are sockets into which adapters are

    connected.

    What is a Bay?

    A bay is a space inside the computer case where a hard drive, floppy drive or CD-ROM drivesits.

    What is a Network?

    A network is the interconnection of computers for the sharing of information and resources.

     

    What is a UTP cable?

    Unshielded Twisted Pair.low frequency transmission medium ,low cost, small size, and ease

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    of installation,limited distance, usually less than 100 meters ,the most popular and is generally

    the best option for school networks.

    What is a File Server?

    A File server is a high capacity computer that provides various resources to the network.

    The heart of a network.Control the communication of information between the nodes on a

    network.Need a very fast computer with a large amount of RAM and storage space, a fast

    network interface card, and a tape back-up device.

      What is a Workstation?

      A computer in a network is called workstation or client.

    What is a Network Interface card?

      NIC provides the link between your computer and your network.provide the physical

    connection between the network and the workstation ,most are internal, with the card fitting into

    an expansion slot inside the computer ,some build on the motherboard.Three common network

    interface connections: Ethernet cards, LocalTalk connectors, Token Ring cards. You canidentify the NIC in the Device Manager on a Windows computer.

    The external port where you plug the cable into the computers looks like a large phone

    connector.

    The connector at the end of the cable is referred to as RJ45 for Ethernet.

      What's the difference between a Hub, a Switch and a Router?

    A hub is typically the least expensive, least intelligent, and least complicated of the

    three. Its job is very simple: anything that comes in one port is sent out to the others.

    That's it. Every computer connected to the hub "sees" everything that every other

    computer on the hub sees. The hub itself is blissfully ignorant of the data beingtransmitted. For years, simple hubs have been quick and easy ways to connect

    computers in small networks.

    A switch does essentially what a hub does but more efficiently. By paying attention to

    the traffic that comes across it, it can "learn" where particular addresses are. For

    example, if it sees traffic from machine A coming in on port 2, it now knows that

    machine A is connected to that port and that traffic to machine A needs to only be sent

    to that port and not any of the others. The net result of using a switch over a hub is that

    most of the network traffic only goes where it needs to rather than to every port. On busy

    networks this can make the network significantly faster.

    A router is the smartest and most complicated of the bunch. Routers come in all shapes

    and sizes from the small fourport

    broadband routers that are very popular right now to

    the large industrial strength devices that drive the internet itself. A simple way to think 

    of a router is as a computer that can be programmed to understand, possibly

    manipulate, and route the data its being asked to handle. For example, broadband

    routers include the ability to "hide" computers behind a type of firewall which involves

    slightly modifying the packets of network traffic as they traverse the device. All routers

    include some kind of user interface for configuring how the router will treat traffic. The

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    really large routers include the equivalent of a fullblown

    programming language to

    What is Network Cables?

    Types of Cables

    Twisted-Pair 10Base TCoaxial

    Fibre-Optics

    10Base2, 10Base5

    Unshielded (UTP)

    Shielded(STP)

    ThinNet

    ThickNet

     

    What is Network Security?  Different rights for different users, such as administrators, teachers, staff, and students

    Access privileges: read, write, execute, or no access,Passwords,Back-up,Virus Protection,

      UPS(Uninterruptible power supply)

     

    What is a Port?

      A connection point for a cable.

     

    Why is Security of data in a computer essential?

      Computers can store both public and private data. You ensure that what is stored onyour computer is secure you can use a password to protect the material. User names and

    passwords can also protect the information stored on a computer. When using the Internet, one

    should use caution when giving out personal information.

    What is a computer software?

    Computer software provides instruction that tell the computer how to operate.Software are also

    called Programs.

    What are the different types of Software?

      System Software:Used by the computer to accomplish a task.controls the internal function

    of the computer ,controls other devices connected to the CPU.

      Application Software:Used by people to accomplish a specific task.Common kinds of

    Application Software are:Word Processor software,Database software ,Spreadsheet

    software ,Games ,Web Page Browsers.

     

    What are the different types of Network?

      A network can be divided into 3 types depending upon the area it covers:

    a)LAN:

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    Local Area Network.Lan is a configuration where all the computers are in close proximity to

    one another.

    Lan connection is created when a Fast Access customer plugs the modem into the computer.

    Lan may serve as few as two or three users or as many as thousands of users.

    b)MAN:Metropolitan Area Network.It is a network of computer's that covers a larger area.

    c)WAN: A WAN computer network is a network that spans a relatively large geographical area.

    A WAN consists of two or more local area networks (LANs)

    Computers connected to a wide-area network are often connected through public networks,

    such as the telephone system.

    Component Overview

    There are several components required to network with other computers.

    Some of the components are:

    Client Software -> 192.168.1.254(IP Address) -> Server Software

    Network Interface card Cable

     

    Network Components

    To communicate with other computers on a network, the following components must be

    present:

    Operating System that supports networking.

    A physical connection to the network.

    A Client

    A Server

    Operating systems

    Windows 98 First and Second Edition

    Windows ME

    Windows NT

    Windows 2000

    Windows XP

    Linux

    Network Operating systems

    Windows NT Server

    Windows 2000 ServerWindows Server 2003

    Linux Server

      What is a Modem?

      Cannot send digital signal directly to telephone line

      Sending end: Modulate the computer's digital signal into analog signal and transmits

      Receiving end: DEModulate the analog signal back into digital form.

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    DSLAM – Digital subscriber line access module(central office ADSL modem pool)

     

    What is a TCP/IP?

      TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication

    language or protocol of the Internet. It can also be used as a communications protocol

    in a private network (either an intranet or an extranet). When you are set up with directaccess to the Internet, your computer is provided with a copy of the TCP/IP program

     just as every other computer that you may send messages to or get information from

    also has a copy of TCP/IP. The IP can be IPv4 or IPv6 (v being version).

    IP address can be identified in the numeric fashion of (for eg) 192.168.1.254

    Application layer

    Transport Layer

    Internet Layer

    Network Interface Layer

    How Bridges Work Bridges work at the Media Access Control Sub-layer of the OSI model

    Routing table is built to record the segment no. of address

    If destination address is in the same segment as the source address, stop transmit

    Otherwise, forward to the other segment

    Bridges and Routers 

    Bridges forward everything they don't recognize

    Route select the best path

    Routers are layer 3 devices which recognize network addressBridges are layer 2 devices which look at the MAC sublayer node address

    What is Startup Repair?

      Startup Repair is a Windows Vista recovery tool that can fix certain problems, such as

    missing or damaged system files, that might prevent Windows from starting correctly. When

    you run Startup Repair, it scans your computer for the problem and then tries to fix it so your

    computer can start correctly.

    Startup Repair is located on the System Recovery Options menu, which is on the Windows

    Vista installation disc. If your computer manufacturer has preinstalled recovery options, Startup

    Repair might also be installed on your hard disk. If your computer does not include Startup

    Repair, your computer manufacturer might have customized or replaced the tool. Check theinformation that came with your computer or go to the manufacturer's website.

     What is a primary memory?

    Programmes and data are stored in the same memory.

    The computer can only perform one instruction at a time.

    Six logical units in every computer:

    1. Input unit : obtains information from input devices (keyboard mouse)

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    2. Output unit : output information (to screen, to printer, to control other devices)

    3. Memory unit : rapid access, low capacity, stores input informations

      ROM (Read only memory): CMOS, EPROM

      RAM(Random Access Memory) : SRAM, DRAM,SIMM, DIMM

    4. Arithmetic and logic unit (ALU) – part of CPU

      Performs arithmetic calculations (addition, subtraction...) and logical decisions

    5. Control unit (CU) – part of CPU

      Supervises and coordinates the other sections of the computer

    6. Secondary storage unit

    Cheap, long term, high capacity storage

    Stores inactive programms

      Addressing Guidelines

      The First Number in the Network ID cannot be 127

      The Host ID cannot be all 255s

      The Host ID cannot be all Zeros

      he Host ID must be Unique to the Local Network ID

    Client/Server Computing on the Internet

    Web Server (HTTP)

    Simple mail transfer protocol (SMTP)

    Domain name serving (DNS) utility

    File transfer protocol (FTP)

    Network news tranfer protocol (NNTP)

    Internet protocol

    HTTP – Hyper Text Transfer Protocol

    FTP - File Transfer Protocol

    SMTP - Simple Mail Transfer Protocol

    HTML - HyperText Markup Language

    DHTML – Dynamic HyperText Markup Language

      Firewall

     A firewall has one point of access into the network. This can be bad or good.

    Can be hardware or software

    Win XP & Mac OS X have built in and third party firewalls

    What is a bus?

    bus is a subsystem that transfers data between computer components inside a computer or

    between computers. Each bus defines its set of  connectors to physically plug devices, cards or

    cables together.

    Computer Components:

    Computers are made of the following basic components:

    Case with hardware inside:

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    Power Supply - The power supply comes with the case, but this component is mentioned

    separately since there are various types of power supplies. The one you should get depends on

    the requirements of your system. This will be discussed in more detail later

    Motherboard - This is where the core components of your computer reside which are listed

    below. Also the support cards for video, sound, networking and more are mounted into thisboard.

    Microprocessor - This is the brain of your computer. It performs commands and instructions

    and controls the operation of the computer.

    Memory - The RAM in your system is mounted on the motherboard. This is memory that must

    be powered on to retain its contents.

    Drive controllers - The drive controllers control the interface of your system to your hard

    drives. The controllers let your hard drives work by controlling their operation. On most

    systems, they are included on the motherboard, however you may add additional controllers for

    faster or other types of drives.

    Hard disk drive(s) - This is where your files are permanently stored on your computer. Also,

    normally, your operating system is installed here.

    CD-ROM drive(s) - This is normally a read only drive where files are permanently stored.

    There are now read/write CD-ROM drives that use special software to allow users to read from

    and write to these drives.

    Floppy drive(s) - A floppy is a small disk storage device that today typically has about 1.4

    Megabytes of memory capacity.

    Other possible file storage devices include DVD devices, Tape backup devices, and some

    others.

    Monitor - This device which operates like a TV set lets the user see how the computer is

    responding to their commands.

    Keyboard - This is where the user enters text commands into the computer.

    Mouse - A point and click interface for entering commands which works well in graphical

    environments.

    Main Components and Structure of the Central Processing Unit  

    What does the CPU do?

    Carries out instructions and tells the rest of the computer system what to do. This is done by the

    Control unit of the CPU which sends command signals to the other components of the system.

    Performs arithmetic calculations and data manipulation, eg. comparisons, sorting, combining,

    etc. The computer's calculator is a part of the CPU known as the Arithmetic logic unit.

    Holds data and instructions which are in current use. These are kept in the Main Store or

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    Memory.

    To understand how the whole system works, consider the diagram shown below. This diagram

    shows the basic components of a generalised CPU. An actual CPU may have these components,

    or other with different names that provide the same functions.

     

    What is the OSI model?

    The OSI, or Open System Interconnection, model defines a networking framework for

    implementing protocols in seven layers. Control is passed from one layer to the next,

    starting at the application layer in one station, and proceeding to the bottom layer, over

    the channel to the next station and back up the hierarchy.

    What are the different layers of the OSI Model?

    Layer 7: The application layer...This is the layer at which communication partners

    are identified, quality of service is identified, user authentication and privacy areconsidered, and any constraints on data syntax are identified. (This layer is not the

    application itself, although some applications may perform application layer functions.)

    Layer 6: The presentation layer...This is a layer, usually part of an operating system,

    that converts incoming and outgoing data from one presentation format to another (for

    example, from a text stream into a popup window with the newly arrived text).

    Sometimes called the syntax layer.

    Layer 5: The session layer...This layer sets up, coordinates, and terminates

    conversations, exchanges, and dialogs between the applications at each end. It deals

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    with session and connection coordination.

    Layer 4: The transport layer...This layer manages the endtoend

    control (for

    example, determining whether all packets have arrived) and errorchecking.

    It ensures

    complete data transfer.

    Layer 3: The network layer...This layer handles the routing of the data (sending it in

    the right direction to the right destination on outgoing transmissions and receiving

    incoming transmissions at the packet level). The network layer does routing and

    forwarding.

    Layer 2: The datalink 

    layer...This layer provides synchronization for the physical

    level and does bitstuffing

    for strings of 1's in excess of 5. It furnishes transmission

    protocol knowledge and management.

    Layer 1: The physical layer...This layer conveys the bit stream through the network at

    the electrical and mechanical level. It provides the hardware means of sending andreceiving data on a carrier.