What is a Network Operating System?

assalamualaikum,.. after i finished my assignment i think that i want to do something...??
Ooo.. my blog.. this is my new entry...

what did you know about NOS?
Unlike operating systems, such as Windows, that are designed for single users to control one computer, network operating systems (NOS) coordinate the activities of multiple computers across a network. The network operating system acts as a director to keep the network running smoothly.

The two major types of network operating systems are:

• Peer-to-Peer
• Client/Server

  Peer-to-Peer

  
  Peer-to-peer network operating systems allow users to share resources and files located on their computers and to access shared resources found on other computers. However, they do not have a file server or a centralized management source . In a peer-to-peer network, all computers are considered equal; they all have the same abilities to use the resources available on the network. Peer-to-peer networks are designed primarily for small to medium local area networks. Nearly all modern desktop operating systems, such as Macintosh OSX, Linux, and Windows, can function as peer-to-peer network operating systems.
  

  Client/Server

  
  Client/server network operating systems allow the network to centralize functions and applications in one or more dedicated file servers (See fig. 2). The file servers become the heart of the system, providing access to resources and providing security. Individual workstations (clients) have access to the resources available on the file servers. The network operating system provides the mechanism to integrate all the components of the network and allow multiple users to simultaneously share the same resources irrespective of physical location. UNIX/Linux and the Microsoft family of Windows Servers are examples of client/server network operating systems.
  
  
   So, what is their the advantages and disadvantages... lalalala
  
  
  
  

  Advantages of a client/server network:

• Centralized - Resources and data security are controlled through the server.
• Scalability - Any or all elements can be replaced individually as needs increase.
• Flexibility - New technology can be easily integrated into system.
• Interoperability - All components (client/network/server) work together.
• Accessibility - Server can be accessed remotely and across multiple platforms.

Disadvantages of a client/server network:

• Expense - Requires initial investment in dedicated server.
• Maintenance - Large networks will require a staff to ensure efficient operation.
• Dependence - When server goes down, operations will cease across the network. 

Advantages of a peer-to-peer network:

• Less initial expense - No need for a dedicated server.
• Setup - An operating system (such as Windows XP) already in place may only need to be reconfigured for peer-to-peer operations.

Disadvantages of a peer-to-peer network:

• Decentralized - No central repository for files and applications.
• Security - Does not provide the security available on a client/server network.

VPN...

What is VPN?

this is my midnight enrty... its usually that i update this blog while im online... this entry is about vpn..

A Virtual Private Network (VPN) is a network technology that creates a secure network connection over a public network such as the Internet or a private network owned by a service provider. Large corporations, educational institutions, and government agencies use VPN technology to enable remote users to securely connect to a private network.
A VPN can connect multiple sites over a large distance just like a Wide Area Network (WAN). VPNs are often used to extend intranets worldwide to disseminate information and news to a wide user base. Educational institutions use VPNs to connect campuses that can be distributed across the country or around the world.
In order to gain access to the private network, a user must be authenticated using a unique identification and a password. An authentication token is often used to gain access to a private network through a personal identification number (PIN) that a user must enter. The PIN is a unique authentication code that changes according to a specific frequency, usually every 30 seconds or so.

IRC???

What did you know about IRC?..here are some entry that i post...
 

Internet Relay Chat (IRC) is a system for chatting that involves a set of rules and conventions and client/server software. On the Web, certain sites such as Talk City or IRC networks such as the Undernet provide servers and help you download an IRC client to your PC. Talk City also offers an IRC client applet that it downloads for you as part of their home page so that you can start chatting right away.
You can start a chat group (called a channel) or join an existing one. There is a protocol for discovering existing chat groups and their members. Depending on the type of network, nicknames can be reserved (registered) or just used during the session. Some channels encourage you to register a nickname that you always use and even offer space for a personal profile, picture, and personal home page link.
Popular ongoing IRC channels are #hottub and #riskybus. A number of channels are set up and conducted in foreign languages. The most common IRC networks are IRCnet (mostly European), EFnet (mostly North American), Undernet, and Dalnet. Popular IRC clients include mIRC for Windows, IRCle for Mac OS, and irc2 (the original client) for UNIX-base operating systems.

Web conferencing...

here is my new entry about web conference... hahahaha
what is web conferencing?

Web conferencing is a form of real-time communications RTC in which multiple computer users, all connected to the Internet, see the same screen at all times in their Web browsers. Some Web conferencing systems include features such as texting, VoIP (voice over IP) and full-motion video.
Web conferencing allows users to carry on business meetings and seminars, make presentations, conduct demonstrations, provide online education and offer direct customer support. Control of the session can be passed among users so that any attendee can act as the main presenter. The most effective Web conferencing solutions require high-speed Internet connections at all user sites.
Several vendors offer Web conferencing services for a nominal monthly fee. System requirements are modest. Most personal computers have sufficient resources to use Web conferencing through their existing browsers. Installation of the supporting software, if any, is easy and there is practically no learning curve.

Advantages :

• Easily accessible to everyone
• It involves real time communication
• Faster than e-mail
• Comes with features such as desktop and application sharing
• Reduces the need for face-to-face meetings, which saves money

Disadvantages :

• Not all software is free, and the free software is limited in what it can achieve
• With overseas conferences, depending on the speed of both of the clients internet, it can greatly reduce the visibility and function of shared desktops and applications
• More informal than a face-to-face meeting
• Requires suitable hardware and adaquate training to be able to function
• Costs to maintain and keep up with new technology

vid codec...

here some example of differ codec... enjoy it and try to feel...eizanie76

COdec.?

Lately I'm busy with assignment, so i could not update my entry as usual.. So, my new entry is about codec. maybe some of my classmates do not understand very briefly.. 
      
     "Codec" is a technical name for "compression/decompression". It also stands for "compressor/decompressor" and "code/decode". All of these variations mean the same thing: a codec is a computer program that both shrinks large movie files, and makes them playable on your computer. Codec programs are required for your media player to play your downloaded music and movies.


 "Why do we need codecs?"

      Because video and music files are large, they become difficult to transfer across the Internet quickly. To help speed up downloads, mathematical "codecs" were built to encode ("shrink") a signal for transmission and then decode it for viewing or editing. Without codecs, downloads would take three to five times longer than they do now. 

"What are the common codecs people use?"

Some codec examples are MP3, WMA, RealVideo, RealAudio, DivX and XviD. There are many other more obscure codecs.

The Difference Between a Computer Virus, Worm and Trojan Horse

• Virus: A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes.
• Trojan horse: A destructive program that masquerades as a benign application. Unlike viruses, Trojan horses do not replicate themselves
• Worm: A program or algorithm that replicates itself over a computer network and usually performs malicious actions
• Blended threat: Blended threats combine the characteristics of viruses, worms, Trojan Horses, and malicious code with server and Internet vulnerabilities .
• Antivirus program: A utility that searches a hard disk for viruses and removes any that are found.   
  
  Tips to Combat Viruses, Worms and Trojan Horses on Your Computer
  
  
  Keep The Operating System Updated
  
  
  The first step in protecting your computer from any malicious there is to ensure that your operating systems (OS) is up-to-date. This is essential if you are running a Microsoft Windows OS. Secondly, you need to have antivirus software installed on your system and ensure you download updates frequently to ensure your software has the latest fixes for new viruses, worms, and Trojan horses. Additionally, you want to make sure your anti-virus program has the capability to scan e-mail and files as they are downloaded from the Internet, and you also need to run full disk scans periodically. This will help prevent malicious programs from even reaching your computer.
  
  
  
  
  
  
  

 

Networking Hardware?

Did you know what it is? this is another entry that i want to share who do not know or who already know about it...

 

there are several parts of the network hardware that we should know:

• file server
• workstations
• network internet cards
• switches
• repeaters
• bridges
• routers 
• firewall
  
  Servers
  
  One or more network servers is a part of nearly every local area network.These are very fast computers with a large amount of RAM and storage space, along with a one or more fast network interface card(s). The network operating system provides tools to share server resources and information with network users. A sophisticated permissions-handling system is included, so that access to sensitive information can be carefully tailored to the needs of the users. For small networks, a singe network server may provide access control, file sharing, printer sharing, email, database, and other services
  
  Workstations
  
  Computers that humans use are broadly categorized as workstations. A typical workstation is a computer that is configured with a network interface card, networking software, and the appropriate cables. Workstations do not necessarily need large storage hard drives, because files can be saved on the file server. Almost any computer can serve as a network workstation.
  
  
  
  Network Interface Cards
  

  
  

  Often abbreviated as NIC, an expansion board you insert into a computer so the computer can be connected to a network. Most NICs are designed for a particular type of network, protocol, and media, although some can serve multiple networks.   

  
  

  

   

  A Wi-Fi network card with an external aerial for the signal

  
  

  Switches
  
  A network cable can only have one data packet in it at any instant.
  So if two or more computers want to place a data packet on to the network at exactly the same time, then a 'data collision' will take place. 
  The network protocol is set up to deal with this. Basically it declares the collided data as unusable and forces the two computers to re-send their data packets at a slightly different time.
  

  

  
   Repeaters
  
  

  All signals fade as they travel from one place to another. 

  
  

  

  
  

  Each type of network cable has a maximum useable length. If you go beyond that length, the signal will be too weak to be useful.
  Of course, computers on a real network can easily be more than 200 metres apart. Therefore the network cable is split up into segments. Each segment is less than the maximum length allowed. Joining the segments together is a device known as a 'Repeater'.
  

  
  

  A Repeater boosts the signal back to its correct level.
  Here are some typical maximum cable lengths:
  

  • Copper cable - 100m
  • Thick Ethernet - 500m
  • Thin Ethernet - 185m

  
  
  Bridges
  

  A Bridge does just what you would expect it to do - it joins two networks together so as far as data packets are concerned it looks like one large network
  A bridge is not as capable as a Router - but it is less expensive.
  Both networks have to be using the same protocol
  
  

  

  
  

  Routers
  
  A Router is a device that transfers data from one network to another in an intelligent way. It has the task of forwarding data packets to their destination by the most efficient route.
  

  When a data packet arrives, the router does the following:-

  - Reads the data packet's destination address

  - Looks up all the paths it has available to get to that address

  - Checks on how busy each path is at the moment

  - Sends the packet along the least congested (fastest) path

  
  

  

  Other tasks the Router can perform:

  - Exchange protocol information across networks

  - Filter traffic - helps prevent unathorised intrusion by malware

Computer Networking

Computer networks are interconnections of many computers. Computers in a network share resources such as electronic mail, bulletin boards, and access to unique databases. Think of them as information highways for data. Networks are changing the computing paradigm from "number-crunching" to communicating. They have spawned a number of industries and helped organizations provide information and communication services to remote customers. In a computer network the individual stations, called nodes, may be computers, terminals, or communication units of various kinds. Networks that are contained within a building or a small geographical area are called local area networks. The largest network connecting computers spread across the globe, is yes, the Internet. Know all the little things you should, about computer networking.

Just for fun...

Advantages and Disadvantages of Different Network Topologies

Network topologies describe the ways in which the elements of a network are mapped. They describe the physical and logical arrangement of the network nodes. Let us look at the advantages the different network topologies offer and get to know their shortfalls.


Bus Topology

Advantages of Bus Topology
It is easy to handle and implement.
It is best suited for small networks.

Disadvantages of Bus Topology
The cable length is limited. This limits the number of stations that can be connected.
This network topology can perform well only for a limited number of nodes.

Ring Topology

Advantage of Ring Topology
The data being transmitted between two nodes passes through all the intermediate nodes. A central server is not required for the management of this topology.

Disadvantages of Ring Topology
The failure of a single node of the network can cause the entire network to fail.
The movement or changes made to network nodes affects the performance of the entire network.

Mesh Topology

Advantage of Mesh Topology
The arrangement of the network nodes is such that it is possible to transmit data from one node to many other nodes at the same time.

Disadvantage of Mesh Topology
The arrangement wherein every network node is connected to every other node of the network, many of the connections serve no major purpose. This leads to the redundancy of many of the network connections.

Star Topology

Advantages of Star Topology
Due to its centralized nature, the topology offers simplicity of operation.
It also achieves an isolation of each device in the network.

Disadvantage of Star Topology
The network operation depends on the functioning of the central hub. Hence, the failure of the central hub leads to the failure of the entire network.

Topology

What is a network topology? In communication networks, a topology is a usually schematic description of the arrangement of a network, including its nodes and connecting lines. There are two ways of defining network geometry: the physical topology and the logical (or signal) topology.


The Physical Topology...
           The physical layout of devices on a network. Every LAN has a topology, or the way that the devices on a network are arranged and how they communicate with each other. The way that the workstations are connected to the network through the actual cables that transmit data -- the physical structure of the network -- is called the physical topology. The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.

 The Logical Topology...
            Also called signal topology. Every LAN has a topology, or the way that the devices on a network are arranged and how they communicate with each other. The way that the workstations are connected to the network through the actual cables that transmit data -- the physical structure of the network -- is called the physical topology. The logical topology, in contrast, is the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
Logical topologies are bound to the network protocols that direct how the data moves across a network. The Ethernet protocol is a common logical bus topology protocol. LocalTalk is a common logical bus or star topology protocol. IBM's Token Ring is a common logical ring topology protocol.

     Types of Network Topologies

Bus Topology: In this type of network topology, all
     the nodes of a network are connected to a common transmission medium having two endpoints. All the data that travels over the network is transmitted through a common transmission medium known as
     the bus or the backbone of the network. When the transmission medium has exactly two endpoints, the network topology is known by the name, 'linear bus topology'. In case the transmission medium, also
     called the network backbone, has more than two endpoints, the network is said to have a distributed
     bus topology. Bus topology is easy to handle and implement and is best suited for small networks. But the downside of this topology is that the limited cable length limits the number of stations, thus limiting the performance to a less number of nodes.

Ring Topology: In a ring topology, every node in the network is connected to two other nodes and the first and the last nodes are connected to each other. The data that are transmitted over the network pass through each of the nodes in the ring until they reach the destination node. In a ring network, the data and the signals that pass over the network travel in a single direction. The dual ring topology varies in having two connections between each of the network nodes. The data flow along two directions in the two rings formed thereby. The ring topology does not require a central server to manage connectivity between the nodes and facilitates an orderly network operation. But, the failure of a single station in the network can render the entire network inoperable. Changes and moves in the stations forming the network affect the network operation.

Mesh Topology: In a full mesh network, each network node is connected to every other node in the network. Due to this arrangement of nodes, it becomes possible for a simultaneous transmission of signals from one node to several other nodes. In a partially connected mesh network, only some of the network nodes are connected to more than one node. This is beneficial over a fully connected mesh in terms of redundancy caused by the point-to-point links between all the nodes. The nodes of a mesh network require possessing some kind of routing logic so that the signals and the data traveling over the network take the shortest path during each of the transmissions.

Star Topology: In this type of network topology, each node of the network is connected to a central node, which is known as a hub. The data that is transmitted between the network nodes passes across the central hub. A distributed star is formed by the interconnection of two or more individual star networks. The centralized nature of a star network provides a certain amount of simplicity while also achieving isolation of each device in the network. However, the disadvantage of a star topology is that the network transmission is largely dependent on the central hub. The failure of the central hub results renders the entire network inoperable.

Tree Topology: It is also known as a hierarchical topology and has a central root node that is connected to one or more nodes of a lower hierarchy. In a symmetrical hierarchy, each node in the network has a specific fixed number of nodes connected to those at a lower level.

Wifi.,.

Wired vs. Wireless

Wired networks offer many advantages over wireless networks, especially in terms of speed and cost, although if your home or business isn't pre-wired with Ethernet cabling it can often end up being quite expensive to add new wiring.  Wired networks also offer security advantages over wireless networks, but most of the security risks of wireless networks can be mitigated with advanced encryption and other wireless security options.   The main advantage to deploying a wireless network, on the other hand, is simply the lack of needing any wiring at all.
In most cases, a combination of both wired and wireless network connections will serve you best, especially if your facility is already wired.  Assuming you'll be deploying either a wireless-only network or a network that combines wired and wireless technologies, let's take a look at the type of wireless network that will best suit your needs.