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					                                   Assignment 1

To be completed by 22nd MARCH 2010

Please place the completed work on the assignment page of your web
site or email . You do not need to hand in a paper copy but you can if
you like.

Email (
1. CSMA/CD and Token are technique used in the media access control or MAC.
   Describe in general how this technique works.
   The CSMA/CD main function was to determine which computer should send data at
   a given moment. Where if one of the hosts is sending data, there would be no
   problem. But if there were two hosts was sending data at the same time, possibly the
   collision will be occur.

   TOKEN, used ring topology where it sent data from original sender to the next
   machine and so on in the circular pattern round until it end up back to the original
   sender (back where it started). There was no collision occur in the TOKEN technique
   because only one machine use the network at any given time.

2. Name the routable and Non-routable protocol. Discuss the advantages and
   Routable protocol:
   Data being sent from one LAN to another LAN along any of several available paths is
   routed. TCP/IP is the 'routable protocol'.
   i. large protocols than the non-routable
   ii. can be used to tie several LANs together
   iii. wide-area environments
   i. non-routable ones, they are slow in everything
   ii. many types of error-checking which increase the size of data-packets.

   Non-routable protocol:
   NetBEUI is non-routable protocol. Non-routable are those protocols, which cannot
   support the communications outside the local network
   i. extremely fast
   i. cannot support the communications outside the local network
   ii. serve limited capabilities
   iii. work only on the similar type of network

3. Using your experience with computer networks make comments on the statement
     below in terms of network security, speed of response, bandwidth, ease of expansion
            “Running Ethernet technology on as network using various media is a
            satisfactory network solution for a modern office environment”.
            Running Ethernet technology on as network using a various media is also worth
            because other user can be accessible. This application should be highly security in
            term of hackers, virus and so on. It would be slow speed as a big network using
            the Ethernet and using a large bandwidth or traffic.

4.          The default gateway on the ITB internal network has an IP address of
  , the and the DHCP, DNS servers IP address are set at
            and Proxy(Router) server IP address is set at and WIN server IP
            address is set at
                   (i)     What is the Default Gateway and what does it do?
                           A configuration item for the TCP/IP protocol that is the IP
                   address of a directly reachable IP router. Configuring a default
            gateway creates a default route in the IP routing table

                   (ii)    What is DHCP, DNS and WINs and why do we need it?

                           DHCP - A computer running the Microsoft DHCP service that
                           offers dynamic configuration of IP addresses and related
                           information to DHCP -enabled clients.

                           DNS – (Domain Name System). A hierarchical, distributed
                           database that contains mappings of DNS domain names to various
                           types of data, such as IP addresses. DNS enables the location of
                           computers and services by user-friendly names, and it also enables
                           the discovery of other information stored in the database.

                           WINs – (Window Internet Name service). A software service
                           that dynamically maps IP addresses to computer names (NetBIOS
                           names). This allows users to access resources by name instead of
                           requiring them to use IP addresses that are difficult to recognize

                   and remember. WINs servers support clients running
                   Windows NT 4.0 and earlier versions of Microsoft operating

           (i)     Why is the Subnet Mask needed?

                   A 32-bit value that enables the recipient of IP packets to
                   distinguish the network ID and host ID portions of the IP address.
                   Typically, subnet masks use the format 255.x.x.x.

5. Computer networks operate in two general modes; client-server and peer to peer.
    List the advantages and disadvantages of each type of operation and give
    examples of where they might be found.
    Peer to peer
   It is a very simple network(simple services such as file and print sharing)
   It is ideal for small offices or groups of people best for sharing lightly used
    resources(a printer or a file)
   No dedicated server(no central server)
   It is low in cost.
   It is easy to install solution.

   A requirement of between 5 to 10 pc only.
   PC lags as the performance might be slow. When rebooting, data may be lost,
    delays in accessing data, reduced productivity and no shared data.
   Facing all kind of dangers such as power outrages, email viruses and incompatible
    applications. (No centralized management or control)
   User error threats.
   Some OS such as Windows 98, has relatively weak security options.

    Advantages of Client-server
    1) All data is stored on the servers.
    2) Multiples different client.
    3) Updates data are easier.

     Disadvantages of Client-server
     1) Overload can happen if there are too many servers.
     2) If the server is down, the client cant do anything.

6.   On a network running the TCP/IP protocol some computers and network
     equipment are assigned static IP addresses whilst others are assigned dynamic IP
     addresses. What is the difference between these two forms of IP address
     allocation and why are they used?
     The difference between Static Ip and IP addresses is that the Static IP is manually
     assigned by the administrator whereas dynamic IP addresses is assigned

     A static IP addresses were used because it translate DNS to IP addresses and
     Dynamic IP addresses were used to allows many devices to share limited address

7.   Discuss Broadcast, Multicast and Unicast.

     Broadcast is sending the information to anybody on the network.

     Multicast is sending the information to specific host on a network.

     Unicast is sending or receiving the information from client to server or vice versa.
     One on one connection only.

8.   Discuss the advantages and disadvantages of BUS, STAR, RING and MESH

     BUS –

              easy to handle and implement
              cable length is limited
              best suited for small networks
              limited number of nodes

     STAR –

            centralized nature
            Operation depending on Hub healthy
            Easy connection of network
            More cable used compare with other (except Mesh)
            Less expensive compare with mesh

     RING -

            central server is not required for the management

            One host down and all host also down

            Data send was pass around till back to original sender

            changes made to network nodes affects the performance of the entire

     MESH -

            All node will received same data at the same time

            Connection was complicated and many node was connected

            No traffic problem for sending data

            Hardware expensive

            Easy to Fault finding for point to point failure

            Wiring is hard to manage

9.   Discuss Shared and User-level security.
     Share-level security - Access control to a file, printer or other network the user
     must know the password of that resource. Share-level security provides less
     protection than user-level security, which identifies each person in the

     User-level - permissions are stored in a central server and managed by the
     network administrator

                                   Formative Test
                                 Computer Networks

   1. What is Computer Networks?
      A computer network, often simply referred to as a network, is a collection of
      computers and devices connected by communications channels that facilitates
      communications among users and allows users to share resources with other users.
      Networks may be classified according to a wide variety of characteristics.

   2. List types of Computer Network?
       LAN - Local Area Network
       WLAN - Wireless Local Area Network
       WAN - Wide Area Network
       MAN - Metropolitan Area Network
       SAN - Storage Area Network, System Area Network, Server Area Network, or
          sometimes Small Area Network

   3. What is topology? List down the type of topology.

   Topology consists of two or more systems connected together. A topology is a schematic
   description of the arrangement of a network, including its nodes and connecting
   lines.Which are bus, star, ring and mesh.

   4. What is protocols; What is routable and non-routable protocol ?
                An agreed-upon format for transmitting data between two device . The
        protocol determines the type of error checking to be used, data compression
        method if any, how the sending device will indicate that it has finished sending a
        message, how the receiving device will indicate that it has received a message

non-routable protocol

   A communications protocol that contains only a device address and not a network
   address. It does not incorporate an addressing scheme for sending data from one network
   to another. Examples of non-routable protocols are NetBIOS and DEC's LAT protocols.


A communications protocol that contains a network address as well as a device address. It
allows packets to be forwarded from one network to another. Examples of routable protocols
are TCP/IP, IPX, AppleTalk, SNA, XNS and DECnet

   5. What is half duplex, simple and full duplex?

   Simplex communication is a name for a type of communication circuit. simplex circuit
   is one where all signals can flow in only one direction.

   A half-duplex system provides for communication in both directions, but only one
   direction at a time (not simultaneously). Typically, once a party begins receiving a signal,
   it must wait for the transmitter to stop transmitting, before replying. Example "walkie-
   talkie" style two-way radio, wherein one must use "Over" or another previously
   designated command to indicate the end of transmission, and ensure that only one party
   transmits at a time, because both parties transmit on the same frequency.

   A full-duplex, or sometimes double-duplex system allows communication in both
   directions, and unlike half-duplex, allows this to happen simultaneously. Land-line
   telephone networks are full-duplex since they allow both callers to speak and be heard at
   the same time. A good analogy for a full-duplex system would be a two-lane road with
   one lane for each direction.

   Examples: Telephone, Mobile Phone, etc.

   6. What are the Share and User Level?
      User Level – user are assigned those privileges when they become a member of that

    7. What is TRACERT?
        Trace Route a computer network tool used to determine the route taken by packets
across an IP network. An IPv6 variant, traceroute6, is also widely available.

   8. What is NSLOOKUP?
   The nslookup command, which stands for "Name Server Lookup", allows you to see
   what IP address, if any, your computer associates with a given domain name.

   Open a Command Prompt and type nslookup, obviously
   changing the "" to whatever URL you are trying to access.

   9. Which MS Windows OS cannot join to Domain?
      A Windows 2000-based computer may be unable to join a Windows NT 4.0-based
domain. When you attempt to change the domain membership for the Windows 2000-based
computer in the Identification Changes dialog box, you receive the following error

   Network Identification:\
   The following error occurred validating the name "domain name".
   The specified domain either does not exist or could not be contacted.

   If you attempt to use the net view command from the Windows 2000-based computer,
   you receive the following error message:
   System error 53 has occurred.
   The network path was not found.

   If you attempt to ping by name from the Windows 2000-based computer does not work.
   Pinging by IP address does work

   This problem can occur if both of the following conditions exist:

          NetBIOS over TCP/IP is disabled on the client computer.
          The TCP/IP protocol is the only protocol installed on the client computer.

   10. What is DNS?

DNS – (Domain Name System). A hierarchical, distributed database that contains mappings
of DNS domain names to various types of data, such as IP addresses. DNS enables the
location of computers and services by user-friendly names, and it also enables the discovery
of other information stored in the database

    11. What is NetBIOS name?
        Net Basic Input/Output System - An application programming interface (API) that
can be used by programs on a local area network (LAN). NetBIOS provides programs with a
uniform set of commands for requesting the lower-level services required to manage names,
conduct sessions, and send datagrams between nodes on a network.

    12. What is WINS?
        Windows Internet Name Service (WINS) is a NetBIOS name resolution service that
allows client computers to register their NetBIOS names and IP addresses in a dynamic,
distributed database and to resolve the NetBIOS names of network resources to their IP

   13. What is DHCP?
       Dynamic Host Configuration Protocol a communications protocol that lets network
       administrators centrally manage and automate the assignment of Internet Protocol
       (IP) addresses in an organization's network.

   14. What cable do you use to link 2 computer together?
       RJ45 Cable

    15. How to resolve MAC address to IP address?
        Assuming your core switch is a multi-layer switch you can do the following
show mac-address-table
show ip arp
Here you can match MAC addresses in your mac-address-table to ARP entries in your ARP
For eg:
show mac-address-table lists the MAC 1234.5678.9abc
then you can do a 'show ip arp | include 1234.5678.9abc'

    16. How to make the website to be secure and encrypted?
        Encrypt HTML source code v.2.0 is an advanced tool for a complete website
Being a web designer, you know how much effort is needed to create a unique, original and
competitive web site. And you know how easy it is your intellectual property to be stolen and
reused by your competitors and anyone else.
    Encrypt HTML source will protect web site content entirely - your code, images,
    links, scripts, java applets and all other components of your web site from thieves, email
    extractor spamming programs, site rippers, web content filters and all other possible
    online threats.

   17. What is IP?
       Internet Protocal which uses a set of rules to send and receive messages at the Internet
address level

   18. What is ICMP?
       A required maintenance protocol in the TCP/IP suite that reports errors and allows
simple connectivity. ICMP is used by the Ping tool to perform TCP/IP troubleshooting.

   19. I can send e-mail but I can’t receive e-mail. What’s the problem?
       Receive problems. If you can receive email from some people but not others, and
can do a successful connection check, then it is likely that your connection is fine and
the sender is having send problems. However, if you can't receive email from anyone,
then try the following:
         Display checks. First, manually recheck for new mail again, and then close
           and reopen your In mailbox to try and reinitialize the display trigger. Then
           resort the In mailbox by the Date/Time field, usually by clicking on the
           Date/Time column header, and then check both the top and bottom of the
           mailbox to see if email was downloaded but listed out of view.

            Filters. Check to see that email you are looking for isn't being filtered out of
             your In mailbox into some other folder before you see it. Check your filter
             folders, and if needed use your email application's "edit / find" function to
             search all mailboxes for an identifying string in the expected email, such as
             the sender's email address.

            Configuration problem. If no new email shows up from the display check, and
             you are certain that messages from several sources are pending, then first
             check your configuration settings, especially your incoming POP server, email
             address, and user name. If you know your email password, try deselecting
             the "save password" option, closing and restarting the program, checking for
             mail, and reentering your password to reinitialize the connection. If these
             suggestions don't work, then contact your email provider for assistance.

   20. What is UDP?

            A TCP complement that offers a connectionless datagram service that guarantees
            neither delivery nor correct sequencing of delivered packets (much like IP).

    21. What is SSL?
        A proposed open standard for establishing a secure communications channel to
prevent the interception of critical information, such as credit card numbers. Primarily, it
enables secure electronic financial transactions on the World Wide Web, although it is
designed to work on other Internet services as well.

    22. What is HTTPS?
        HTTP (Hypertext Transfer Protocol) is the set of rules for transferring files (text,
graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon
as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is
an application protocol that runs on top of the TCP/IP suite of protocols (the foundation
protocols for the Internet).

   23. What is APIPA?
       APIPAAutomatic Private Internet Protocol Addressing (IP address range 169.254.x.z)
   APIPAArizona Physicians Independent Practice Association APIPA, also known as
   Automatic Private IP Addressing, is a feature used in Windows operating systems. It
   comes into action only when DHCP (Dynamic Host Configuration Protocol) servers are
   available. When the DHCP client first comes on, it will try to establish a connection with
   the DHCP server in order to get an IP address. It is when this server is (or at a later point
   becomes) unavailable, that APIPA will kick in. As the client is unable to connect with the
   server, APIPA will automatically try to configure itself with an IP address from an
   specially reserved range. (This reserved IP address range goes from to

    24. What is IMAP?
        The Internet Message Access Protocol (IMAP) is one of the two most prevalent
Internet standard protocols for e-mail retrieval, the other being the Post Office Protocol
(POP).[1] Virtually all modern e-mail clients and mail servers support both protocols as a
means of transferring e-mail messages from a server.

   25. What is RARP?
       Short for Reverse Address Resolution Protocol, a TCP/IP protocol that permits a
       physical address, such as an Ethernet address, to be translated into an IP address.
       Hosts such as diskless workstations often only know their hardware interface
       addresses, or MAC address, when booted but not their IP addresses. They must
       discover their IP addresses from an external source, usually a RARP server. RARP is
       defined in RFC 903.

    26. What is SNMP?
        A network protocol used to manage TCP/IP networks. In Windows, the SNMP
service is used to provide status information about a host on a TCP/IP network.

   27. What is peer to peer network?
       Peer-to-peer (P2P) networking is a method of delivering computer network
       services in which the participants share a portion of their own resources, such as
       processing power, disk storage, network bandwidth, printing facilities. Such
       resources are provided directly to other participants without intermediary
       network hosts or servers.

    28. What is fat-client based network?
        A fat client or rich client is a computer (client) in client-server architecture networks
which typically provides rich functionality independently of the central server. Originally
known as just a 'client' or 'thick client', the name is contrasted to thin client, which describes
a computer heavily dependent on a server's applications.
    A fat client still requires at least periodic connection to a network or central server, but is
    often characterised by the ability to perform many functions without that connection. In
    contrast, a thin client generally does as little processing as possible and relies on
    accessing the server each time input data needs to be processed or validated.

    29. What is thin-client network?
        A thin client (sometimes also called a lean or slim client) is a computer or a
computer program which depends heavily on some other computer (its server) to fulfill its
traditional computational roles.[1] This stands in contrast to the traditional fat client, a
computer designed to take on these roles by itself. The exact roles assumed by the server may

vary, from providing data persistence (for example, for diskless nodes) to actual information
processing on the client's behalf.

   30. What is speed of CAT 3 and CAT 5?
       Cat 5 and Cat 5e UTP cables can support 10/100/1000 Mbps Ethernet. Although Cat
       5 cable may support to some degree in Gigabit Ethernet (1000 Mbps), it performs
       below standard during high-data transfer scenarios, so I do not recommend you to use
       Cat 5 cable in Gigabit Ethernet, use Cat 5e instead (of course Cat 6 is the best).
   Cat 6 UTP cable is manufactured targeting on Gigabit Ethernet and backward compatible
   with 10/100 Mbps Ethernet. It performs better then Cat 5 cable with higher transmission
   rate and lower transmission error. If you plan to have Gigabit network, look for Cat 5e or
   Cat 6 UTP cables.

   31. List the connectors for fiber optic?

   32. What is HUB, MAU, BRIDGE and GATEWAYS?
       A hub is used in a wired network to connect Ethernet cables from a number of
devices together. The hub allows each device to talk to the others. Hubs aren't used in
networks with only wireless connections, since network devices such as routers and adapters
communicate directly with one another.

         Short for Multistation Access Unit (also abbreviated as MSAU), a token-ring
network device that physically connects network computers in a star topology while retaining
the logical ring structure. One of the problems with the token-ring topology is that a single
non-operating node can break the ring. The MAU solves this problem because it has the
ability to short out non-operating nodes and maintain the ring structure. A MAU is a special
type of hub.

      a bridge is a product that connects a local area network (LAN) to another local area
network that uses the same protocol (for example, Ethernet or Token Ring).

        A gateway is a network point that acts as an entrance to another network. On the
Internet, a node or stopping point can be either a gateway node or a host (end-point) node.
Both the computers of Internet users and the computers that serve pages to users are host
nodes. The computers that control traffic within your company's network or at your local
Internet service provider (ISP) are gateway nodes.

     33. What is OSI layer?
is the 7 important layer that used for
      Application
      Presentation
      Session
      Transportation
      Network
      Data Link
      Physical

    34. What is ASDL, CSU/DSU, Frame Relay, ISDN and Dial-Up?
        Abstract-Type and Scheme-Definition Language (ASDL) is a computer language
developed as part of ESPRIT project GRASPIN, as a basis for generating language-based
editors and environments. It combines an object-oriented type system, syntax-directed
translation schemes and a target-language interface.

A CSU/DSU (Channel Service Unit/Data Service Unit) is a digital-interface device used to
connect a Data Terminal Equipment device or DTE, such as a router, to a digital circuit (for
example a T1 or T3 line).

Frame Relay is a standardized wide area networking technology that specifies the physical
and logical link layers of digital telecommunications channels using a packet switching
methodology. Originally designed for transport across Integrated Services Digital Network
(ISDN) infrastructure, it may be used today in the context of many other network interfaces.

Integrated Services Digital Network (ISDN) is a set of communications standards for
simultaneous digital transmission of voice, video, data, and other network services over the
traditional circuits of the public switched telephone network. It was first defined in 1984 in
the CCITT red book.

Dial-up Internet access is a form of Internet access that uses telephone lines.[1] The user's
computer or router uses an attached modem connected to a telephone line to dial into an
Internet service provider's (ISP) node to establish a modem-to-modem link, which is then
used to route Internet Protocol packets between the user's equipment and hosts.

   35. List down 802 IEEE standard. (12 of them)

               a.   Ethernet
               b.   Token bus
               c.   Fibre Optic tag
               d.   Bridging
               e.   Wireless PAN
               f.   WI-FI
               g.   Mobile broadband wireless access

               h. Cable modem
               i. Logical link control
               j. Intergrated service LAN
                  k. MAN – Metropolitan Area Network

   36. What is RAID ? Explain RAID 1 and 5.

RAID, an acronym for Redundant Array of Inexpensive Disks or Redundant Array of
Independent Disks, is a technology that allows high levels of storage reliability from low-
cost and less reliable PC-class disk-drive components, via the technique of arranging the
devices into arrays for redundancy.

         RAID Level 1 provides redundancy by writing all data to two or more drives. The
         performance of a level 1 array tends to be faster on reads and slower on writes
         compared to a single drive, but if either drive fails, no data is lost. This is a good
         entry-level redundant system, since only two drives are required; however, since
         one drive is used to store a duplicate of the data, the cost per megabyte is high. This
         level is commonly referred to as mirroring.

       RAID Level 5 is similar to level 4, but distributes parity among the drives. This can
       speed small writes in multiprocessing systems, since the parity disk does not
       become a bottleneck. Because parity data must be skipped on each drive during
       reads, however, the performance for reads tends to be considerably lower than a
       level 4 array. The cost per megabyte is the same as for level 4.

    37. What is the difference between incremental and differential backup?
         Incremental backup - A backup that copies only those files created or changed since
the last normal or incremental backup. It marks files as having been backed up (in other
words, the archive attribute is cleared). If you use a combination of normal and incremental
backups to restore your data, you will need to have the last normal backup and all
incremental backup sets.

         Differential backup - A backup that copies files created or changed since the last
         normal or incremental backup. It does not mark files as having been backed up (in
         other words, the archive attribute is not cleared). If you are performing a
         combination of normal and differential backups, restoring files and folders requires
         that you have the last normal as well as the last differential backup.

    38. What is the port number of FTP, SMTP, POP3?
        FTP – (File Transfer Protocol). A member of the TCP/IP suite of protocols, used to
copy files between two computers on the Internet. Both computers must support their
respective FTP roles: one must be an FTP client and the other an FTP server.

   POP3 – (Post Office Protocol 3). A popular protocol used for receiving e-mail
   messages. This protocol is often used by ISPs. POP3 servers allow access to a single
   Inbox in contrast to IMAP servers, which provide access to multiple server-side folders.

SMTP – (Simple Mail Transfer Protocol). A member of the TCP/IP suite of protocols that
governs the exchange of electronic mail between message transfer agents.

   39. What is Data Encyption standard and Public-key Encyption?
       Data Encryption Standard - IPSec in Windows XP uses the US Data Encryption
Standard (DES) to provide confidentiality (data encryption). This prevents the entire data set
from being compromised if one DES key is broken.

Public-key Encryption - A method of encryption that uses two encryption keys that are
mathematically related. One key is called the private key and is kept confidential. The other
is called the public key and is freely given out to all potential correspondents. In a typical
scenario, a sender uses the receiver's public key to encrypt a message. Only the receiver has
the related private key to decrypt the message. The complexity of the relationship between
the public key and the private key means that, provided the keys are long enough, it is
computationally infeasible to determine one from the other. Public key encryption is also
called asymmetric encryption.

    40. What is Viruses and other destructive programs ?
        Viruses - A program that attempts to spread from computer to computer and either
cause damage (by erasing or corrupting data) or annoy users (by printing messages or
altering what is displayed on the screen).

    41. What are SLIP, PPP and PPTP?
        SLIP - Serial Line Internet Protocol (SLIP) is an older remote access standard
typically used by UNIX remote access servers. Network Connections supports SLIP, and you
can make connections to any remote access server by using the SLIP standard.

        PPP - Point-to-Point Protocol (PPP). An industry standard suite of protocols for the
        use of point-to-point links to transport multiprotocol datagrams.

        PPTP - Point-to-Point Tunneling Protocol (PPTP). Networking technology that
        supports multiprotocol virtual private networks (VPNs), enabling remote users to
        access corporate networks securely across the Internet or other networks by dialing
        into an Internet service provider (ISP) or by connecting directly to the Internet. The
        Point-to-Point Tunneling Protocol (PPTP) tunnels, or encapsulates, IP, IPX, or
        NetBEUI traffic inside of IP packets. This means that users can remotely run
        applications that are dependent upon particular network protocols.

   42. What is TDR and Tone Generator?

        TDR - A TDR (Time Domain Reflectometer) is used for sending signals through a
        network medium to check cable continuity and other attributes.

        Tone Generator – is also used for check the cable continuity which sending a value
        of frequencies through the cable to its destination.


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