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5.
Ans.
networking has been all of the buzz in the Internet marketing world for the last several years. At first it represented a vague approach to visiting a new class of websites and trying to establish a presence for your business or website on them. These networks are collectively known as the world of web 2.0, otherwise known as social networking or social media sites. We now know that one of the keys to generating traffic to your website can be found through these new channels.

A social networking site is any website, service or tool on the Internet today that makes use of community interaction, placing a premium on the user to create his or her own content, to share it with others and to connect with other users. Many of the most popular websites on the world today fall into this spectrum, from Facebook to Twitter to YouTube. So how can these be used to be successful at generating traffic for your online business?

The problem that most people encounter is that they expect to be able to log on to one of these services, create an account and expect a viral storm of traffic on their doorstep the next day. While social networking for generating traffic can be simple, it's not that simple, and you do need to apply some more effort than that in order to succeed.

The number one rule is that you cannot expect one of these services to be an outlet for your advertisements or for your press releases. You can't just walk out there, spewing about your company and expect to see results. What you need to do is become a real member of the community - that's what social networking is all about isn't it? You need to actively participate in discussions, reply to posts, follow what other people are saying, add people to your friends list, create and join groups and more.

When you do all of this you create a real presence for yourself that can lead to generating traffic the likes of which you've never seen before. You'll become a real, respected voice in your community and people who feel the same way about the same issues will follow you and end up checking up on your website. Even if you're not voicing strong opinions you can still reach out to others by just getting out there, making yourself known and connecting with as many other people on the service that you can.

Social networking is all about using the web to connect with other people, and to share your own voice. Businesses therefore have been eager to tap into this massive force for many reasons, including generating traffic back to their websites. Many have failed because they simply do not understand the basics - that you really need to participate and get involved. If you can master this concept and actively engage your community, then you'll succeed with social networking.

3.
Ans.

The OSI model are explained below. The seven layers of the OSI model are:

• Application
• Presentation
• Session
• Transport
• Network
• Antiqua">Data Link
• Physical

1 Application layer:
This layer provides a means for the user to access information on the network through an application. Many user applications that need to communicate over the network interact with the Application layer protocol directly. The user applications are not part of OSI Application layer, use the networking services offered by the networking protocol suite. Application layer functions typically include identifying communication partners, and determining availability of required resources. Some examples of application layer implementations include Telnet, File Transfer Protocol (FTP), and Simple Mail Transfer Protocol (SMTP).

2 Presentation layer:
Presentation layer converts local host computer data representations into a standard network format for transmission on the network. On the receiving side, it changes the network format into the appropriate host computer's format so that data can be utilized independent of the host computer. ASCII and EBCDIC conversions, cryptography, and the like are handled here.
Examples of Presentation layer coding and conversion schemes include common data representation formats, conversion of character representation formats, common data compression schemes, and common data encryption schemes.

Presentation layer implementations are not typically associated with a particular protocol stack. Some well-known standards for video include QuickTime and Motion Picture Experts Group (MPEG). QuickTime is an Apple Computer specification for video and audio, and MPEG is a standard for video compression and coding.

3. Session layer:
The session layer establishes, manages, and terminates communication sessions. Communication sessions consist of service requests and service responses that occur between applications located in different network devices. These requests and responses are coordinated by protocols implemented at the session layer. Some examples of session-layer implementations include AppleTalk's Zone Information Protocol (ZIP), and Decent Phase Session Control Protocol (SCP).

4.Transport layer:
Transport layer is responsible for providing reliable service between the hosts. Upper layer datagrams are broken down into manageable datagrams and then appropriate header information (such as sequence number, port number, etc.) is added to the datagram before passing it on to the Network layer. Two frequently used transport protocols are the TCP (Transmission Control Protocol) and the UDP (User Datagram Protocol).

Important features of Transport layer:

• Transport layer ensures reliable service.
• Breaks the message (from sessions layer) into smaller datagrams, and appends appropriate unit header information.
• Responsible for communicating with the Session layer

Important features of TCP/UDP:

• TCP/IP widely used protocol for Transport/Network layers
• TCP: (Transport Control Protocol) TCP ensures that a packet has reached its intended destination by using an acknowledgement. If not, it retransmits the lost messages. Hence, TCP is called a connection oriented protocol.
• UDP (Universal Data gram Protocol): UDP simply transmits packets over the internet. It does not wait for an acknowledgement. It is the responsibility of upper layer protocols to ensure that the information had reached the intended partner(s). Hence, UDP is often called connectionless protocol.
• Application programs that do not need connection-oriented protocol generally use UDP.

5. Network layer:
Network layer is responsible for the routing of packets through the entire network. The layer uses logical addressing for this purpose. Note that the physical address (like MAC address) keeps changing from hop to hop when a packet travels from source to destination. As a result, an address that doesn't change is required to ensure continuity between hops. This is nothing but logical address. For IP networks, IP address is the logical address; and for Novell network, IPX address is the logical address, and so on. This layer also provides for congestion control, and accounting information for the network. IP (Internet Protocol) is an example of a network layer protocol.

6. Data link layer:
Data link layer provides delivery of information frames between communicating partners. This layer is responsible for flow regulation, error detection and correction, and framing of bits for transmission. The network data frame is made up of checksum, source address, destination address, and the data itself. The largest frame size that can be sent is known as the maximum transmission Unit (MTU).

Important features of Data link layer:

• Assembles bits into frames, making them ready for transmission over the network.


• Provides error detection, and correction to transmitted frames. If the checksum is not correct, it asks for retransmission. (Send a control message).


• Consists of two sub layers:
  1. Logical Link Control (LLC): Defines how data is transferred over the cable and provides data link service to the higher layers.
  2. Medium Access Control (MAC): Controls media access by regulating the communicating nodes using pre-defined set of rules. (i.e. Token passing, Ethernet [CSMA/CD] all have MAC sub-layer protocol).
  
  

Different Data link layer protocols define different network and protocol characteristics, including physical addressing, network topology, error notification, sequencing of frames, and flow control. Physical addressing (as opposed to logical addressing) defines how devices are addressed at the data link layer. The protocols used in Data link layer are SLIP, PPP, and CSLP.

7. Physical layer:
This is the bottom-most layer of the OSI model. The Physical layer handles the bit-level communications across the physical medium. The physical medium could be made up of wired electrical signals, or light, or radio (wireless) signals. Physical layer specifications define characteristics such as media, data rates, maximum transmission distances, and physical connectors.

Some of the important standards that deal with physical layer specifications are:

RS-232(for serial communication lines), X.21, EIA 232, and G730.

Physical layer and Data link layer implementations can be categorized as either LAN or WAN specifications.

Vijayanand has done his post graduation (M.E.) in Communication Systems. He has several years of experience in electronic assembly and design, rf testing, and networking. He is a Cisco Certified Networking Professional, and an MCSE (Microsoft Certified Systems Engineer). He is a director of Anand Software and Training Pvt. Ltd. Complete tutorial on Networking is available at SimulationExams.com

2.ans.
computer network topology is the physical communication scheme used by connected devices. These pages illustrate the common computer network topologies including bus, ring and star topology diagrams. More complex networks can be built as hybrids of two or more of these basic topologies.

1.ans. is the physical interconnections of the elements (links, nodes, etc.) of a computer network.^[1][2] A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more other nodes in the network and the mapping of these links and nodes in a graph results in a geometrical shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flows between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.