Computer Viruses Problems and Solutions

We all are now aware with the term Computer Viruses

Let’s understand this simple definition: Computer Viruses can be considered as small software application which tends to take control over computer operation. The computer virus may delete contents from the hard disk and even take a ride on e-mail programs to become pandemic. Computer viruses be in various formats like in form of images, audio or video files. They may spread while downloading files from the Internet. Sometimes they may be purchased along with the pirated software too.

Let’s concentrate on symptoms of Viruses

There can be difficulty in accessing any disk or drive. The system might be running slow. Sometimes it may freeze. You may see distorted menus and dialog boxes. Any program may disappear on its own without any action. Sometimes you may see some new icons on the desktop. Application will not be running smooth. You may get error of any system file missing. Your windows may restart automatically sometimes. If you see this kind of symptoms on your system, then install any latest version of anti virus which you think compatible with the Operating System you have. Scan your system for the Computer Viruses. Even in severe condition you may need to format your system completely.

Let’s see what we can do to remove a Virus

You need to apply a Computer Viruses removal tools for the purpose. Sometimes you may find specific problems which are associated with some unwanted software programs which carries Computer Viruses You may get those viruses again in your system after uninstalling those programs. So you should be very much smart while choosing for the Tools for Computer Viruses removal.

To remove virus, follow these steps

1. Visit the Microsoft website to get latest updates from Microsoft Updates.

2. Perform regular scanning of your system with any updated Anti- Virus.

3. Download, install, and then run the Microsoft Malicious Software Removal Tool to remove Computer Viruses the system.

Preventive measure for Computer Virus

Its highly recommended you to keep your Operating systems updated. If you are not online don’t forget to check for Windows updates frequently. This is important because the Virus creator always tries to make use of any void in your Operating System to install their software Computer Viruses. If you are online user then make sure that your web browser is also an updated one. Try to use the most compatible and latest of the Web browser may be from any one like IE, Firefox, Opera or anyone else, because the Virus writer always tries to find mistakes in your browser.

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The Leading Gaming PC Cases Are Essential To Help Protect and Power Your Extreme Gaming Hardware

Gaming PC Cases come in a variety of shapes and sizes. From rack mount to ATX tower casing, you can find one that best suits your gaming needs. Many games are played by as many 15-24 users and such games require the power of hardware to control both the graphics and many millions of instructions to the CPU with great speed. Custom Gaming PCs are the current rave with game lovers who strive for a better playing experience, adding more hardware.

With a large variety of casing, it is confusing to choose the right one. A good PC Case for gaming is one that has ample space to add more fans and USB ports. Heating is the main problem that slows down the PC and in some instances can damage it. Looks also matter a lot, an attractive and next-gen look, makes for a better playing experience.

All gaming PC cases come with microphones and headphone sockets, while the more advanced ones have fan controllers. New game players can do with two fans while some want to get additional fans to keep the PC from heating up. More advanced users utilize much of CPU power, and need more cooling.

When you are ready to buy a case, first look at the price options, compare various makes and models and see where you can save money and get the same functionality. The most accommodating case is considered the best. It will allow for more fans, and offers ample space for advanced graphic cards. Check to see, if the case can allow more than 4 fans and has at least two USB ports.

Some cases come with 4 USB ports and have space for up to six fans. If you are an advanced level player, you may want to consider one that has a fan speed controller, so you can monitor the cooling easily. Further up the ladder, there are cases that come with space for as many as 12 hard drives. Such a case, can take any kind of mother board you want to use.

The ATX are more popular these days and are like the industry standard. ATX form-factor allows for better air passage so all components can stay cool. It uses less cable, generates less heat and is more affordable. The expansion slots are easily accessible making it easy for users to add more graphic cards.

Looks wise, a clear panel looks attractive and spices up the computer using LEDs. There are also cases with bright graphics, and a modish look to add to the adventure. It all depends on your game choice, if you like a good thrill considering Gaming PC Cases that will add excitement to game time.

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Turn Your Basement Into a Virtual Shooting Gallery

An indoor shooting simulator is easy to add on to most projection based home theater systems, and in most cases is an inexpensive way to add hours of entertainment for the whole family. People of all ages enjoy playing the wide range of games that are available for the system, everything from “Baseball Challenge” to “Elephant Hunter” will keep your family and friends entertained. Utilizing a shooting simulator is not only a great way to add excitement to your home theater room; it is also a get way to keep your shooting skills sharp.

System Basics:

There are a few basic requirements for adding a shooting simulator to an existing home theater. The simulator runs on a normal Windows based computer, software is compatible with Windows XP, Windows Vista and Windows 7. The image is broadcast through a projector to a screen, which most projectors and home theater screens will be suitable for use with this simulator. Now all you need to add is a basic simulator package, which includes a rifle, case, camera and five games. Installation of the simulator will only take about thirty minutes to setup and install the new software and hardware. Now you are ready to start enjoying the very best of simulated shooting. To recap the items you need: computer, projector, screen and a simulator package.

Benefits of Indoor Shooting:

There are many advantages to adding an indoor shooting simulator to you home theater room, these are just a few.

Convenience- having the ability to practice your shooting skills from within your own house, cuts down on drive time to the range and you can fire up your system anytime you want.

Cost Savings- ammunition is expensive! You will save a lot of money practicing your skills using a true to life replica laser firearm verses using live ammo.

Safety- using a laser firearm is a much safer weapon to practice will and it’s a lot better for your hearing.

Shooting Variety- with a shooting simulator you have the ability to practice your skills on a wide range of software titles. You can practice shooting skeet and with just a touch of a button you can switch over to another game and practice your marksmanship on simulated popup targets.

Entertainment- Gather you friends and family, challenge them for the highest score or for bragging rights.

Packages and Software:

With this system, there are many packages of both hardware and software available. Looking for a portable package or maybe a complete package if you don’t have a projector, computer and screen? Those packages and more are available. There are over 35 software titles currently available, which can be purchased separately or in 15 game packages. Software titles are being added, so you will always have the option to buy the latest games on the market. Do you have the best Halloween party on your block? There is a Halloween software package that will insure your party is unforgettable. Do you have a young hunter or marksman that could benefit from “Hunter’s Education” software? It is an option on this simulator. Teach them everything from ethical shooting to animal anatomy, with the hunter’s Ed package. Looking to hone your archery skills? This simulator has packages available for you bow enthusiasts. There are several optional firearms which can be added to the system, to maximize the skill development and enjoyment of the simulator.

Adding a shooting simulator to your theater room is easy and a cost effective way of increasing the entertainment value of your room as well as improve shooting skills. If you would like some more information on the shooting simulators or have any questions please contact me through the website.

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Schedule Slippage – Root Causes

“The single most important task of a project: setting realistic expectations. Unrealistic expectations based on inaccurate estimates are the single largest cause of software failure.”- Futrell, Shafer

Introduction

With global and competitive market, it is very important to launch a product or service in the market on time, ahead of competitors. Definitely, timely launch depends on on-time-completion of the product development projects. Project planning has lots of challenges to overcome in order to finish the project on time – right from schedule predictability, envisioning future/possible risks and coming up with mitigation plans.

This article talks about some of the challenges, often faced in the Software Product Development industry that causes the schedule slippage.

Schedule slippage: Delay in the project completion from its initial estimated date of completion.

Each project plan will have a planned completion date (NRA, RA), and a bounding box or upper limit in schedule. Nowadays, it is a common practice to have three dates associated with any project plan:

  • Non-Risk Adjusted (NRA) date: Project completion date assuming no hurdles – Ideal conditions.
  • Risk Adjusted (RA) date: Project completion date assuming some risks will come on the way and will need extra time to attend to them.
  • Bounding Box (BB) or upper limit: The upper limit on the project plan before which the project has to be finished under any circumstances – Generally decided by the top management based on product/services roadmap and launch in the market.

Under ideal circumstances, any project is scheduled to complete by NRA date. Considering some risks that may come on the way and would eat some time off the schedule, the project should be over by RA date. If the risks were not envisioned and hence not planned well, then project may get delayed and would complete after RA date. Project completion crossing the RA or upper limit is neither good nor expected out of a well-planned project.

Root Causes

As we always plan for a project to get over before RA date, seldom is the case it happens as expected. There are multiples reasons for schedule slippage, right from improper planning, lack of resources to unplanned requirements and rework that eat away vital time off the planned schedule.

A typical project development process – Each project will have a team (development, testing and other functions) that will work through a process (requirement analysis, schedule estimation, design, implementation and testing) to deliver a product to the customer/end user. Each entity that participate in the project – directly or indirectly affect the schedule.

From the development process, we can identify the items that can cause delay in the execution of the project – for example, misinterpreted or unclear requirement adds up to completion time, unavailability of development tools or resources can prolong the project duration. Various processes like schedule estimation, detailed design and product development if not executed skillfully, may significantly blow up the project cycle.

For better understanding all these possible causes that may result in schedule slippage are categorized .

Let’s have a detailed look at the root causes of schedule slippage category wise.

1) Schedule Estimation: “The key is not to prioritize what’s on your schedule, but to schedule your priorities.” – Stephen Covey

For a project to be executed on time, it is very important to have it planned very well. Any mistake in project schedule estimation reflects as delay in the project completion from its deadline. There are several factors that contribute to improper schedule estimation:

· Underestimation of technical complexities: At the start of the project, many of the team members may not have thorough knowledge of technical complexities and hence their estimation would be incorrect. Sometimes it may so happen that the person giving estimates for a particular task is having no idea about the technical challenges involved in carrying out that particular task. You might hear, towards the mid/end of the project life cycle when the task is not finished on time – “Oh, I didn’t know that this feature also requires 5 more tasks to be done!” or “I was thinking this task to be so simple, but I under estimated it!”. · Lack of Design/Big picture: It is important to have a bigger picture / overview of the complete project to understand how a particular module/feature would fit in to complete project. Product or system level design helps in understanding the interfaces among other modules and the required coordination for product assembly and hence, a better insight into the work involved. Often, estimates without focus on detailed design tend to deviate more from the actual time taken for finishing the job. · Integration Testing: While making a project plan, testing also needs to be accommodated in the schedule. At times, the unit testing or testing done by individual contributors on their module is taken into account but not the system level testing. Toward the release, when all the individually tested modules are brought together, a system level or integration testing is a must. Having the time for integration testing not accounted in the overall project schedule will cause delay in the project completion.

· Unplanned dependencies: Project planning is not only about breaking the project into minute tasks and managing them. A well-planned project schedule also needs to consider certain unplanned dependencies. Some of these are:

o People: Optimum utilization of human resources calls for same set of people working in multiple projects. A person may not be available to work for currently planned/assigned project due to extended/unplanned work in another parallel project. Another issue related to people could be unplanned/unexpected attrition that will affect the project plan. Time is also lost in mentoring of new member by a senior (more experienced) person which goes unaccounted if not planned.

o Tools & Equipments: Project can be delayed if team is waiting for release of upgrade or procurement of any vital tool (hardware or software being used in the project) or if the equipments required for development and testing are not available. “We had a 3-months project for validating our existing solution on new product platform using customer DUT (device under test). We had to wait for the DUT for nearly 1.5 months as it got stuck in customs. After getting the DUT, we realized that it’s been damaged partially during transportation. As a result we had to ask for another DUT and whole project took more than 5 months to get finished.” – I am sure that such cases will be quite familiar to many organizations. Other reason for timely unavailability of tools / equipments is that they are shared among various projects to reduce the operating cost. Any unplanned dependency on their usage or wrong assumption about availability of these shared resources would cause delay in the program. Team members might have to work on shifts to optimize the usage of shared resources which can cause reduced work hours and/or productivity loss and results to schedule slippage.

“I was waiting for Matlab license to be released by another person in the team but he left the office without doing so and I lost 3 hours figuring out what to do?” – is it something you faced before?

o Other programs: If multiple programs have deliverable dependencies, then delay in one project will have cascaded effect on other projects, which directly or indirectly depend on its deliverable. “We got delayed because we had to wait for a critical UI component from the framework project team” or “We didn’t plan for bug fixes for a component which was supposed to be delivered defect free for our usage” are the common scenarios for delays in program which are dependent on other program deliverables. Parallel programs may affect the schedule of your program in a different way as well – Sometimes, management changes the priority of the programs running in parallel. If your project is considered as a low priority one then there might be lack of resources assigned to your project that may result in schedule slippage.

· Beta releases: How many times we seek feedback on our product during development? And how often we allocate time for it? It’s important to plan beta releases if we desire to have our product validated by expert users or lighthouse customers during development. Getting feedback from beta customers becomes important especially when their requirements echo that of a mass customer base. Process of giving workable releases to customers, collecting their experience, having their feedback analyzed, and then incorporating in the final product version takes significant time.

· Risk mitigation and plan B: Every project will have some or the other risks. These risks can be of varying severity and probabilities. While making project plan, it is important to treat the risk individually based on their severity and probability of occurrence. If high probable risks with higher severity are not planned with their mitigation plan (or plan B), they will have huge impact on schedule deviation from planned one. As in one of the previous examples quoted, getting a DUT on time for validation was a risk. Had there been a mitigate plan (plan B) like – Validate with other DUT or if DUT is not available here, let one developer travel to customer’s place and finish the validation on time, the schedule slippage would have been avoided.

2) People: Ultimately, projects are executed by people who may not be skilled or talented. Hence, looking for perfection in projects involving human beings may not be a feasible thought. Certain unpredictable and hence unavoidable issues under this category are:

· Poor leadership: Before thinking of project execution, it is project planning that actually would set the platform of success. Execution of the project depends on its team while planning is taken care by the project leader. The project leader is expected to have enough technical know-how to understand the project goals and to the details of the tasks involved. Poor leadership and superficial knowledge of assignments often results in invalid effort estimation and ad hoc task delegation causing stress and possible delay in project execution. People leading the team are also responsible for keeping the team spirit and motivation level upbeat. Poor personal commitment due to lack of motivation results in loss of productivity and may cause schedule to slip. Another reason that adds up to delay in projects is inability of leadership team to track the schedule progress and take the correction action.

· Attrition: If the project duration is large and job market is hot, it may be difficult to retain people in the project till its completion. Attrition may further delay the completion especially if the person leaving the job was in critical path. A person leaving the organization would leave a gap in the project that a new person may not fill immediately, which in turn causes sudden reduction in the task force.

· Learning curve: When ever a new person or team member is included in the project, he or she may require some time to understand the project to keep in pace with other members. Learning curve is needed for new team members, joining the team either due to attrition or due to any specific technical competency requirement. · Context switching: In smaller organization or groups where people work on multiple projects simultaneously, it is important to have some buffer for context switching. A person planned to work in project ‘A’ for two hours after a gap of two weeks, would take more than scheduled time to complete that task. Gap of two weeks and the fact that he or she was involved in other project would require some time for the member to get back to the context of current project. · Global development teams: In an era of globalization and outsourcing, it is common these days to have development team distributed over different geographical regions. Project plan needs to account for different time zones and working culture. You might expect an input for your task on Monday morning your time but it may be Sunday late evening for that person and finally when the input arrives, you might be on your way to home after work.

Sometimes schedule estimation might go completely wrong if you have not understood the work culture of the region your teammate belongs to – “In my previous work, I was given a task to be completed with a heads up that its very critical task and needs immediate attention’. When I asked my project lead how many days/hours I have for it, I had been time for 2 weeks for high priority and ‘immediate-attention’ work.” Definition of ‘urgent’, ‘high priority tasks’ changes with culture and region.

· Communication Issues: People communicate differently. If important issues are not brought to the notice of the team members, or are not escalated on time, the entire project may suffer. Often fear of embarrassment stops team members from reporting issues faced during execution leading to more time being spent on that task that can easily be executed additional help.

3) Customer Involvement: These issues are quite serious if customer or end users of the product are involved in the development phase. Understanding customer’s priorities, defining your expectation from their involvement needs to be clear and in agreement with both the parties.

· Expert user testing: In the beginning of the project, expert user testing cycle needs to be planned. Process of giving builds or releases for testing and collecting their feedback, analyzing and incorporating them in your product takes significant time which, if not planned, can delay your program. · Timely feedback: “I got feedback from customers for features, delivered in development milestone-1, after milestone-5 towards the release. These feedbacks are critical but now I am worried how to incorporate them without affecting the schedule.” It sounds like a common problem. Incorporation of feedback from customers needs to be planned well taking a commitment from the customer. · Product requirement specification review: Having a product requirement review planned and executed will keep you on right track throughout the project. Reviewing the requirement specification will avoid requirement related defects fixing which otherwise would have delayed, the project.

4) Ambiguous Project Requirement: For any project to be initiated, the first thing is to have requirements for it. In the product development life cycle, requirement phase acts like a foundation. Clear requirement or vision for the project navigates the team to success. However, requirements may not be clear at the time of estimation and may result in delay in the project completion. Issues related:

· Evolving specs: If you are making a product based on a standard which is not yet matured or still evolving, you are more prone to have this risk. Frequency changes in the specs will change the requirement for the project during different stages of product development and team will continue to work on something that is not yet evolved. This results in rework that would delay the project if time for dealing with these changes is not accommodated in the schedule. “We developed an algorithm and hence measurement that was based on certain industry standard. Towards the release of the product, the specs changed and our measurement was no more valid. We had to redo the algorithm to reflect the changes in the specs. This caused our product release delayed by 2 months.” · New requirements: Sometimes new requirements are added as the project evolves towards completion. Implementation of new requirements is not planned at the beginning of the project and hence is not accounted in schedule. Adding new feature without revising the schedule may result in delay.

· Untold expectation: Requirements from the customers may be of two types – implicit or explicit. It is important to have the requirements well documented. Implicit requirements needs to be better defined and documented to avoid any confusion towards the end of the project. Customers may not describe their requirements related to system performance, memory issues, user interface quality and usability but they are very keen on providing feedback in those aspects once the product is given for expert user testing. If we are not clear about such requirements, out design might not address them. Addressing them towards the end of the project may call for design changes and extra work that would delay the project.

5) Unplanned Tasks / Reworks: Bounding box for the project is set by higher management and often lack buffer for unplanned task(s). Having more of unplanned task that creep up at different phases of project can cause schedule slippage. The unplanned tasks or rework may arise due to:

· Sustaining work: In smaller organizations, some of the project team may also be responsible for sustaining / customer support of existing products. These unplanned tasks, which come on event basis, related to customer support are always of high priority. Excess or prolonged sustaining work may take resource out of the planned project causing a potential threat for schedule slippage. · Defect fixes: Defects are bad as they degrade the product quality and consume extra time/effort to fix them. It is good to have testing of the intermediate releases of the project to find and fix defects sooner in the development life cycle. If the fixing-cycle for such internal-milestone defects is not planned, then either the project is either going to slip or product is going to be of poorer quality. Poor programming skill of the team, not adapting to modern programming practices and having ad hoc development processes may lead to higher number of defects which would take more time to fix then planned and cause slippage.

· Task spillover from previous milestone: Tasks that are not completed in previous milestone, due to whatever reason (inefficiency, vacation of the team member, resource crunch etc), will have to be completed in the next milestone thereby increasing the load on the team. If adequate buffer is not planned, these tasks spilled from previous milestone over to next, can delay the project. · Requirement change / refinement: Requirement changes during the product development will result in rework of what has been previously done with first version of requirement(s). Addressing changes in the requirements needs extra time and effort and may cause schedule slippage. In some cases, the requirement from customer is misunderstood resulting in wrong system design and implementation. Additional, unplanned time is lost in correcting the design/implementation which causes schedule slippage.

Conclusion

On time delivery is the challenge software development companies are facing globally. To have a complete control over estimated schedule, it is very important to identify the elements in the development cycle that cause schedule slippage. This article uncovers and explains the root causes of delay in programs using examples from real world. Having an insight to the root causes will help the program managers to make good decisions to avoid future schedule slippage.

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Wide Area Network (WAN)

Types and Characteristics of WANs

What is a WAN?

There are two prevailing definitions of a Wide Area Network (WAN). The book definition of a WAN is a network that spans large geographical locations, typically to interconnect multiple Local Area Networks (LANs). The practical definition of a WAN is a network that traverses a public network or commercial carrier, using one of several WAN technologies

What are its Main Components?

The main components for a WAN are routers, switches and modems. These components are described below in the hardware section.

CPE – Devices on the subscriber contracts are called customer premises equipment (CPE).
The subscriber owns the CPE or leases the CPE from the service provider. A copper or fiber cable connects the CPE to the service provider's nearest exchange or central office. This cabling is often called the local loop, or "last-mile".

DTE / DCE – Devices that put data on the local loop are called data circuit-terminating equipment, or data communications equipment (DCE). The customer devices that pass the data to the DCE are called data terminal equipment (DTE). The DCE primarily provides an interface for the DTE into the communication link on the WAN cloud.

Hardware

In a WAN you will need various types of hardware components for it to function. The typical items of hardware that you will need in a WAN are:

Router – An electronic device that connects a local area network (LAN) to a wide area network (WAN) and handles the task of routing messages between the two networks. Operates at layer 3, and makes decisions using IP addresses.

Switch – A switch is a network device that selects a path or circuit for sending a unit of data to its next destination. Operates at layer 2, and uses MAC addresses to send data to correct destination.

Modem – Short for modulator / demodulator, a modem that enables a computer to communicate with other computers over telephone lines. Operates at layer 1, where signals are converted from digital to analogue and vice versa for transmission and receiving.

Wan Standards

WANs operate within the OSI model using layer 1 and layer 2 levels. The data link layer and the physical layer. The physical layer protocols describe how to provide electrical, mechanical and functional connections to the services provided by the ISP. The data link layer defines how data is encapsulated for transmission to remote sites.

Encapsulation

Encapsulation is the wrapping of data in a particular protocol header. Remember that WANs operate at the physical layer and the data link layer of the osi model and that higher layer protocols such as IP are encapsulated when sent across the WAN link. Serial interfaces support a wide range of WAN encapsulation types, which must be manually specified. These types include SDLC, PPP, Frame delay etc. Regardless of WAN encapsulation used it must be identical on both sides of the point to point link.

Packet and Circuit Switching

Circuit switching and packet switching are both used in high-capacity networks.
The majority of switched networks today get data across the network
Through packet switching.

Circuit-switching is more reliable than packet-switching. Circuit switching is old and expensive, packet switching is more modern.

General Routing Issues

What is a Routing Protocol?

A routing protocol is a protocol that specifies how routers communicate and exchange information on a network. Each router has prior knowledge of its immediate neighbors and knows the structure of the network topology. The routers know this because the routing protocol shares this information.

Protocol

RIP (Routing Information Protocol) was one of the most commonly used protocols on internal networks. Routers use RIP to dynamically adapt changes to the network connections and communicate information about which networks routers can reach and the distance between them. RIP is sometimes said to stand for Rest in Pieces in reference to the reputation that RIP has for breaking unexpectedly and rendering a network unable to function.

Routing Algorithms

Distance Vector

This type of routing protocol requires that each router simply inform its neighbors of its routing table. The distance vector protocol is also known as the bellman-ford algorithm.

Link State

This type of routing protocol requires that each router maintain a partial map of the network. The link state algorithm is also know as Dijkstra's algorithm.

IGRP

IGRP is a type of distance vector routing protocol invented by cisco used to exchange routing data in a autonomous system. Distance vector protocols measure distances and compare routes. Routers that use distance vector must send all or a portion of their routing table in a routing update message at regular intervals to each neighbor router.

Addressing and Routing

What does routing mean?

Routing is the process of deciding how to move packets from one network to another.
The directions also known as routes can be learned by a router using a routing protocol then the information is passed from router to router along the route of the destination.

IP Address's

Every machine connected to the internet is assigned an IP address. An example of an IP address would be 192.168.0.1. IP addresses are displayed in decimal format to make it easier for humans to understand but computers communicate in binary form. The four numbers that separate an IP address are called Octets. Each position consists of eight bits. When added to together you get 32 ​​bit address. The purpose of each octet in an IP address is to create classes of IP addresses that can be assigned within a network. There are three main classes that we deal with Class A, B and C. The octets of an IP address are split into two parts Network and Host. In a class A address the first octet is the network portion, this determinates which network the computer belongs to, the last octets of the address are the hosts that belong to the network.

Sub netting

Sub netting allows you to create multiple networks within a class A, B or C address. The subnet address is the address used by your LAN. In a Class C network address you would have a subnet mask of 255.255.255.0. A subnet mask identifies which portion is network and which is host. For example 192.168.6.15 the first octet three octets are the Network address and the last octet being the host (Workstation). It is important to subnet a network because gateways need to forward packets to other LANS. By giving each NIC on the gateway an IP address and a Subnet mask it allows the gateways to route packets from LAN to LAN. Once the packet arrives at its destination, the gateway then uses the bits of the subnet portion of the IP address to decide which LAN to send the packets.

Circuit Switched Leased Lines

A circuit switched network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Here are some terminologies associated with a Circuit switched network.

Frame relay is a telecommunication service designed for cost-efficient data transmission between local area networks (LANs)

Basic rate interference is a service used by small business for internet connectivity. An ISDN BRI provides two 64 Kbps digital channels to the user.
Primary rate interface (PRI) is a telecommunications standard for carrying voice and data transmissions between two locations
All data and voice channels are ISDN and operate at 64kbit / s

Packet Switching

Http://www.raduniversity.com/networks/2004/PacketSwitching/main.htm – _Toc80455261

Packet switching refers to protocols in which messages are broken up into small packets before they are sent. Each packet is then transmitted over the Internet. At the destination the packages are reassembled into the original message. Packet switching main difference from Circuit Switching is that that the communication lines are not dedicated to passing messages from the source to the destination. In Packet Switching, different messages can use the same network resources within the same time period.

Http://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode

Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and protocolwhich encodes data into small fixed-sized cells.

ISDN is used to carry voice, data, video and images across a telephone network. ISDN stands for integrated services Digital Network. Isdn also provides users with a 128kbps bandwidth. This is done through frame relay. Frame relay complements and provides a service between ISDN, which offers bandwidth at 128 Kbps and Asynchronous Transfer Mode which operates in somewhat similar fashion to frame relay but at speeds from 155.520 Mbps or 622.080 Mbps. Frame relay is based on the older X.25 packet switching technology and is used to transmit analogue signals such as telephone conversations.

PSDN stands for packet switched data network and is a data communication network. Packet switched networks do not establish a physical communication signal like the public telephone circuit (circuit switched network) Packets are sent on a fixed length basis and assigned with a source and a destination address. The packages then explicitly on the routers to read the address and route the packets through the network.

Mobile and Broadband Services

Digital Subscriber Line (DSL) is mainly used to bring high bandwidth connections to homes and small business's over a copper wire telephone line. This is can only be achieved if you stay within the range of the telephone exchange. DSL offers download rates of up to 6mbps allowing continuous transmission of video, audio and 3D effects. DSL is set to replace ISDN and compete with the cable modem in providing multimedia to homes. DSL works by connecting your telephone line to the telephone office over copper wires that are twisted together.

Asymmetric Digital Subscribers Line is most commonly used for home users. It provides a high download speed but a lower upload speed. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.

Http://en.wikipedia.org/wiki/Symmetric_Digital_Subscriber_Line

Symmetric Digital Subscriber Line is a digital subcriber line which runs over one pair of copper wires. The main difference between ADSL and SDSL is the difference in upload and download speeds. SDSL allows the same upstream data rate and downstream data rate as ADSL upstream can be very slow.

[Http://searchnetworking.techtarget.com/sDefinition/0],,sid7_gci558545,00.html

HDSL High bit-rate Digital Subscriber Line, one of the earliest forms of DSL, is used for wideband digital transmission within a corporate site and between the telephone company and a customer. The main characteristic of HDSL is that that provides equal bandwidth in both directions.

IDSL is a system in which data is transmitted at 128 Kbps on a regular copper telephone line from a user to a destination using digital transmission.

The Local Loop enables operators to connect directly to the consumer via copper local loops and then add their own equipment to offer broadband and other services. This process involves operators accessing local exchange buildings to connect to a network of copper lines which connect them to homes and businesses. BT is an Example of a Local Exchange. The local loop connecting the telephone exchange to most subscribers is capable of carrying frequencies well beyond the 3.4 kHz upper limit.

Benefits of using DSL

DSL can provide a virtual instantaneous transmission of voice, data and video over ordinary copper phone lines. A DSL connection can eliminate delays while waiting to download information and graphics from the Internet. It provides users with a cost effective high speed Internet connection. Another benefit is that a DSL connection is always on-line (like a LAN connection) with no waiting time for dialing or connecting.

There are now more than 10 million broadband connections in the UK. By December 2005 there were 9.792 million broadband connections in the UK and the average broadband take up rate during the three months to December was more than 70,000 per week.

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How to Repair DBF Files by Using DBF Recovery Software

As a computer user you must have heard about a DBF file or some of you have used it. DBF is a database file format used by various database software programs, such as: Visual FoxPro, Clipper, dbFast, CodeBase, MultiBase, dbXL, Arago and similar database programs. A database file is a collection of data organized in a tabular form. A DBF file can be easily opened, edited and saved by any of these database programs therefore, this file format is very popular among computer users.

The most common use of a database file is to store a large amount of data and information. The file is widely used in almost every sector, such as: corporate and educational sectors to store the data and information. It has become an essential file format for an individual and an organization.

Where this file format is very useful for users on the other hand, it may create some serious problems as well. Sometimes a DBF file may become inaccessible or invalid due to corruption. DBF is not immune to corruption; in fact, this file format is prone to corruption due to its large size and complex file structure. It might be easily corrupted due to various reasons, such as: virus attacks, malfunction in database application, hard disk drive failure, software collision, unexpected cancellation of DBF, human errors and many more. These are some common reasons which can play an important role in database file corruption.

While opening a corrupt DBF file you may receive some error messages something like these:

  • “File .dbf does not exist”.
  • “The fields in table did not match the entries in the database”.
  • “Access to table disabled due to previous error”.
  • “Database file appears corrupt: Page is of wrong type.
  • “Corrupt table”/ “index header”.
  • “Filename .dbf has become corrupted”.

These are some common errors which frequently take place at the time of corruption. For example: you are working on your DBF file, everything is fine. But all of a sudden your database application (Visual FoxPro or other) starts hanging. You have no other option other than restarting the system. But when you restart your system and open the same DBF file, in which you were working earlier, it does not open or you get an error message saying the file is corrupted or damaged. This must be very frustrating situation for any user since all the hard work will go into the vain. All the data and information stored in the file might be lost forever. You have to re-create the file, which might not be possible in some cases.

In such critical state a BKF file will definitely help you. If you have backed up the database file (which is now corrupted), then you can easily restore it from the BKF file. But sometimes the BKF file may not be available or corrupted or invalid. In this situation you can use third-party DBF recovery software. This is one of the most efficient and effective solutions to fix corrupt DBF files. The DBF recovery software is designed to repair an extremely corrupted DBF file and to restore maximum data from it. It is highly capable to resolve or fix all the errors from corrupted DBF files. The software supports all popular database applications, such as: dBase III, dBase IV, dBase V, Visual FoxPro, Clipper, dBFast, CodeBase, MultiBase, dBXL and Arago. The best feature of the software is its self-describing user interface. It requires no technical knowledge or skills to use this software. Any tech savvy and a novice user can easily and comfortably use this software to repair corrupted DBF files. The DBF Recovery software is available with free demo version. Users can download the demo version before buying the full software. This helps users to examine the features and performance.

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Futon Frame Maintenance and Common Replacement Parts and Hardware

A little preventative maintenance of your futon frame can greatly increase how long it lasts. We recommend checking the bolts on your futon frame every month or two, depending on how often it's used. If they are loose, gently tighten them, but be careful not to over tighten them. If you have a wooden frame, you can rub a bar of Ivory soap in the arm tracks every now and then, to keep things operating smoothly.

Most of the damage that we see is from forcing the frame to operate, when it's stuck. If you are converting your frame from a bed to a sofa, or from a sofa to a bed, and it does not easily convert, stop what you are doing, and remove the mattress, and carefully examine why it's not moving easily. Usually if you try to convert the frame and you pull on one side more than the other, something will jam, and if forced, you may break something.

Normally a guest will try to make their bed in the morning, and not knowing how to do it, they may break your frame. We suggest telling your guests to leave the futon as a bed, and you'll take care of changing it from a bed to a sofa for them.

Some parts wear out, and some of the plastic parts can dry out over the years. If the bolts are not tightened, a part can move around in a way that it's not recommended to, and that can cause it to break. People ask us why they do not make some of the parts in futon frames out of metal so they're never break. The reason is, if they were metal, and something jammed up, and was forced, the seat, or back, or an arm would crack, and that would be a more costly repair.

Here's a list of some of the more common futon frame hardware and parts. This is by no means a complete listing of all the parts, but it includes most of the common parts. Some items are called more than one name, so we list them twice. Futon store that has been around a long time, might even have obsoleste parts that you might need.

If you need a part that you can not find anywhere, consult a good futon store who's willing to help you, and give them a description and a couple of pictures showing what you need and see if they are willing to help you. They may need to know the name of the manufacturer of the frame because there are many frames that look the same, but the size of the bolts or seat decks and other items will all be slightly different.

Futon Bolts
Standard Futon Hinges
Click Click Hinges
Triple Click Hinges
Futon Mattress Storage Bags
Oblong Rollers
Carriage Blocks
Round Futon Rollers
Double Futon Rollers
Nylon Roller Inserts
Futon Barrel Nuts, Nuts, and Cross Dowels
Larger Futon Barrel Nuts
Futon Seat Stoppers
Futon Storage Bags
Allen Wrenches
Larger Allen Wrenches
Plastic Leg Caps
1/2 "Futon Hardware Sets
5/8 "Futon Hardware Sets
Angle Support Brackets
Decorative Bolt Covers or Plugs
Clevis Pins and Assemblies
Various Plastic Rollers, Glides and Carriage Blocks
Stretcher Support Rails
Futon Seat Decks
Futon Back Decks
Futon Arms
Cotter Pins
Washers and Clips
Futon Slats and Supports

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Examples Of Spyware And What They Are

Spyware is a general term used to describe software that performs certain behaviors such as advertising, collecting personal information, or changing the configuration of your computer, generally without appropriately obtaining your consent first.

Spyware is often associated with software that displays advertisements (called adware) or software that tracks personal or sensitive information.

That does not mean all software that provides ads or tracks your online activities is bad. For example, you might sign up for a free music service, but you “pay” for the service by agreeing to receive targeted ads. If you understand the terms and agree to them, you may have decided that it is a fair tradeoff. You might also agree to let the company track your online activities to determine which ads to show you.

Other kinds of Spyware make changes to your computer that can be annoying and can cause your computer slow down or crash.

These programs can change your Web browsers home page or search page, or add additional components to your browser you don’t need or want. These programs also make it very difficult for you to change your settings back to the way you originally had them.

The key in all cases is whether or not you (or someone who uses your computer) understand what the software will do and have agreed to install the software on your computer.

There are a number of ways Spyware or other unwanted software can get on your computer. A common trick is to covertly install the software during the installation of other software you want such as a music or video file sharing program.

Any software that covertly gathers user information through the user’s Internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of freeware or shareware programs that can be downloaded from the Internet; however, it should be noted that the majority of shareware and freeware applications do not come with SpyWare. Once installed, the Spyware monitors user activity on the Internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers

Aside from the questions of ethics and privacy, SpyWare steals from the user by using the computer’s memory resources and also by eating bandwidth as it sends information back to the spy ware’s home base via the user’s Internet connection. Because SpyWare is using memory and system resources, the applications running in the background can lead to system crashes or general system instability.

Because SpyWare exists as independent executable programs, they have the ability to monitor keystrokes, scan files on the hard drive, snoop other applications, such as chat programs or word processors, install other SpyWare programs, read cookies, change the default home page on the Web browser, consistently relaying this information back to the SpyWare author who will either use it for advertising/marketing purposes or sell the information to another party.

Licensing agreements that accompany software downloads sometimes warn the user that a SpyWare program will be installed along with the requested software, but the licensing agreements may not always be read completely because the notice of a SpyWare installation is often couched in obtuse, hard-to-read legal disclaimers.

Examples of SpyWare

These common SpyWare programs illustrate the diversity of behaviors found in these attacks. Note that as with computer viruses, researchers give names to SpyWare programs which may not be used by their creators. Programs may be grouped into “families” based not on shared program code, but on common behaviors, or by “following the money” of apparent financial or business connections. For instance, a number of the SpyWare programs distributed by Claria are collectively known as “Gator”. Likewise, programs which are frequently installed together may be described as parts of the same SpyWare package, even if they function separately.

o CoolWebSearch, a group of programs, takes advantage of Internet Explorer vulnerabilities. The package directs traffic to advertisements on Web sites including coolwebsearch.com. It displays pop-up ads, rewrites search engine results, and alters the infected computer’s hosts file to direct DNS lookups to these sites.

o Internet Optimizer, also known as DyFuCa, redirects Internet Explorer error pages to advertising. When users follow a broken link or enter an erroneous URL, they see a page of advertisements. However, because password-protected Web sites (HTTP Basic authentication) use the same mechanism as HTTP errors, Internet Optimizer makes it impossible for the user to access password-protected sites.

o Zango (formerly 180 Solutions) transmits detailed information to advertisers about the Web sites which users visit. It also alters HTTP requests for affiliate advertisements linked from a Web site, so that the advertisements make unearned profit for the 180 Solutions Company. It opens pop-up ads that cover over the Web sites of competing companies.

o HuntBar, aka WinTools or Adware,WebSearch was installed by an ActiveX drive-by download at affiliate Web sites, or by advertisements displayed by other SpyWare programs-an example of how SpyWare can install more SpyWare. These programs add toolbars to IE, track aggregate browsing behavior, redirect affiliate references, and display advertisements.

oZlob Trojan or just Zlob, Downloads itself to your computer via ActiveX codec and reports information back to Control Server. Some information can be as your search history, the Websites you visited, and even Key Strokes.

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3 Main Causes of Kernel Errors

A kernel error is a failure in some code critical to Windows. If you have ever encountered a Blue Screen of Death (BSoD), then you have seen a kernel error. Windows is actually several layers of programs made to work together. You can think of Windows as if it were your body, with many pieces working together to make a whole, and, like your body, some parts of Windows are more important than others.

The kernel is the most important part of Windows. It includes critical programs to handle things like memory management and device drivers for the graphics card. These programs are like a body's heart and brain. If something in the kernel crashes, it will often cause all of Windows to crash.

Software Failures

Because there are a lot of programs in the kernel, there are many opportunities for bugs to appear. Although Microsoft does extensive testing to get rid of bugs, their testing facilities can not run through all the combinations that billions of computers use with Windows when some bugs get through.

However, many of the kernel failures are in device drivers written by companies that make hardware, not by Microsoft. Your graphics card, for example, probably uses a driver created by the video company. These companies often work with Microsoft to test their drivers, but having companies working together adds an additional layer of complexity.

Hardware Failures

A hardware failure can cause a kernel error. If your graphics card fails, it can send bad data to the graphics device driver, which then crashes, creating a kernel error. If your hard disk fails, it can corrupt files used by Windows and cause the programs that use those files to crash.

Registry Failures

Registry failures can cause kernel errors. The registry is a database of information that Windows uses to store information about programs. If the registry gets corrupt, the programs that use it can cause kernel errors.

Registry corruption can come from either software or hardware failures. Software corruption can come from a bug in one of the programs that writes information out to the registry. Or if you turn off your computer without doing a complete shutdown, the registry files may not get completely written to the disk. Hardware corruption can happen when the hard disk fails causing parts of the registry files to be lost. It's a good idea to do some research on kernel errors and other registry issues.

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How Useful is CAD Software to Engineers and Architects?

The emergence of advanced technology has made people today dependent on machines. Using computers and software, for example, is a very common illustration of this. Computer experts are coming up with more and more software to make more and more jobs easier.

A more specific illustration of this can be found in the modern approach towards engineering and architecture. These days, professionals in these fields use CAD computer software which is a program that allows them to create designs faster, easier and with more accurate measurements. Aside from the convenience that CAD software brings, it also helps put architects and engineers ahead of their competitors. CAD, which can render designs that are two-dimensional or three dimensional, stands for Computer Aided Design and has been in use since 1982.

So how does CAD computer software work? And what does it do exactly to help engineers and architects? The program is actually multifaceted in the sense that there are many ways it can help. To make CAD work will require, however, a careful study of its features and the many ways it can be used. It is rather a complex yet flexible and highly functional program.

This article will not be enough to discuss the various ways that CAD works but pinpointing its advantages could give some very good ideas. One great advantage of CAD computer software is its easy-to-use tools in the creation and alteration of designs. Obviously, this is so much better than the old fashioned way of using a pencil and eraser directly on paper. This method of designing is obviously so much easier and engineers and architects simply have more time to finish other tasks. In other words, high productivity is going to be the main end result of using CAD.

Before the design is actually printed on paper, CAD also allows both the design professional and the client to preview what has been finished so far. Any alterations can be made simply by manipulating the drawing through the use of the software. With CAD, it is so much easier to spot errors because the designs can be rendered exactly as they would be in reality. Hence, modifications can be done even before printing, thus, allowing one to save.

With the tough competition that everyone has to face these days, it is wise to take advantage of new technologies that can help put them ahead in the race. While traditional methods hold a significant part in the history of design, advanced tools such as CAD software should only be welcomed as man’s way of furthering development in a field of expertise that he himself has created long ago.

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