Passing The CCNA And CCNP: Cisco Home Lab FAQ

There is a real revolution today among CCNA and CCNP candidates. More and more of you are turning your back on "router simulators" and putting your own CCNA and/or CCNP Home Lab together, which is the best way to totally prepare to pass these tough Cisco exams.

I get hundreds of emails every month from CCNA and CCNP candidate who are putting together their first lab or adding to their existing one. I'm always glad to help with suggestions, and I thought I'd list five common questions regarding home labs here.

Do I have to spend thousands of dollars?

No! There are vendors all over the web, as well as on ebay, who sell used Cisco routers and switches to Cisco exam candidates like you every single day. They sell kits that consist of multiple routers and switches, as well as single routers and switches. You can add one piece at a time, or make a larger investment. You can spend just a few hundred dollars and put together a very nice lab.

What's an "access server"?

It's not what it sounds like. When I first heard the term, I thought of a typical server like we see in LANs every single day. An access server is actually a Cisco router that allows you to connect to multiple other routers and switches without continually moving the rolled cable around.

You don't have to have an access server right away, but once you add a few more routers and switches to your lab, you'll get tired of moving the rollover cable from console port to console port. (The console port is used to directly connect your PC to the router.) You'll find an access server is easy to set up and configure, and will save you quite a bit of time. 

What's a "frame relay switch"?

Again, it's not quite what it sounds like. A frame relay switch is not a switch; it's a Cisco router that has been configured to serve as a frame relay provider in your home lab.

This is very close to being a "must" for your home lab. You don't need it right away if your budget allows for only one or two routers to get started. To truly practice frame relay map statements and see the effect of different frame relay statements, you'll need a Cisco router to serve as a frame switch. Again, the configuration is easy, and having a frame relay switch in your home lab will give you practice that will be invaluable on exam day.

Do I need a switch? What switch should I buy?

I recommend you get at least one switch in your lab; two if your budget allows. Make sure that at least one of your switches has an IOS; 1900 switches do not have an IOS and while they're better than not having a switch, they're not going to give you the practice you need to pass the CCNA and CCNP. Look to the 2500 family of switches.

I want to build my CCNP lab and then use it for the CCIE. What should I buy?

It's impossible to tell what technologies and devices will be on the CCIE lab, even if you zip through the CCNP and then take the IE within six months. Cisco refreshing the CCIE lab blueprint every six months, and different technologies can be taken off the lab. While Cisco gives plenty of notice that these changes are going to take effect, it can be a big pain in your wallet if Cisco takes something off of the exam after you spend a bundle to add it to your lab.

As an example, Cisco is in the process of removing ISDN and ATM from the CCIE Routing & Switching lab. If you bought an ATM switch for your lab, you've got an expensive paperweight right now. While you may be able to practice your core protocols on a CCIE home lab, it's going to be difficult and expensive to keep your home lab totally current with the Cisco lab blueprint.

The decision to put together your own CCNA or CCNP home lab is the best decision you can ever make - and I speak from experience. With home labs becoming less expensive every day, it's becoming more affordable as well. Start looking into used Cisco router vendors today (ebay is a great place to find some vendors, as is Google), and you can be practicing on REAL Cisco routers and switches soon - and be totally prepared for CCNA and CCNP exam success. 

Protect Your Computer With Zone Labs

 Zone Labs is the most trusted name in Internet security, and with good reason. The Zone Labs products are effective at keeping computers protected from spyware, hackers and other Internet bad guys without clogging up your system. 

They're also easy to install and configure to meet your needs. Zone Labs' products offer a range of services depending on what you need and want from an Internet protection program. 

ZoneAlarm, the most basic firewall program offered by Zone Labs, can be downloaded for free and used for personal, non-business use. 

ZoneAlarm Antivirus adds the Zone Labs triple-defense firewall, antivirus protection, e-mail security and protection for your wireless network. 

Zone Labs' ZoneAlarm Anti-Spyware offers the same features as the antivirus program except with anti-spyware protection instead of antivirus. 

The added power of ZoneAlarm Pro includes Zone Labs' identity theft and privacy protection programs, e-mail security and anti-spyware. 

The all-in-one solution from Zone Labs is ZoneAlarm Internet Security Suite, which includes the basic and triple defense firewalls, anti-spyware, antivirus, identity theft and privacy protection, anti-phishing and spam blocker, e-mail security, instant messenger security, parental controls and protection for wireless PCs. 

You can also buy the instant messenger security and parental controls separately from Zone Labs in the product IMsecure Pro. 

These products from Zone Labs can give you peace of mind as they protect your computer from a variety of problems you don't want to have. Zone Labs can protect you from hackers, spam, viruses, identity theft and more. Stop these menaces before they get to your computer and your information, with a little help from Zone Labs

Zone Labs is the trusted leader in Internet protection and personal firewall systems. More than 30 million computers worldwide are trusted to Zone Labs products. And it couldn't be easier to protect your computer from all of the various threats that are out there when one Zone Labs product can do it all for you. 

The Zone Labs products are easy to install and use but still very powerful. They allow customers to protect themselves without a lot of effort or thought on their part. Zone Labs also allows more knowledgeable users to fine-tune the settings on their products to give them exactly what they need from the firewall and Internet protection package. 

If you need technical help when working with any product from Zone Labs, you can find support online, via e-mail and through the ZoneAlarm Support Center. Zone Labs is there with you to help make your Internet systems work for you and protect your computer in the best way possible. 

There's no better feeling than being able to get online and know that your computer is safe from viruses, hackers and identity thieves. Zone Labs can give you that kind of security. 

Television Tuners, Making Television on your Computer Possible

Television tuners allow a user to watch television on their computer monitor. There are several different types of television tuners which we will discuss in this article.

The most common type of television tuner for a computer is the USB television tuner. USB ports are common on all computer so this type of connectivity make it possible to connect the tuner to pretty much any computer.

The television tuner acts just like a normal television would but with the need for a bulky antenna. USB television tuners can receive standard definition, or high definition signals depending of the type of tuner you have.

Most television tuners are bundled with some sort of software. This software allows the user to record the streaming television onto their computer so they can watch programs at a later date. In most cases this software is easy to use and easily setup.

Television tuners are constantly evolving. The newest wave of television tuners allow the user to use two streams from the one tuner. Meaning, you can record one television show while watching another. This is very convenient but at present, only one stream can be recorded and the recorded stream cannot be viewed in conjunction with the non-recorded stream.

Television tuners are a great way to watch television on notebook computers. With the portability of notebook computers, watching television anywhere your notebook can go is possible.

Television tuners can be bought for different prices depending on the quality of the product and the features/software they provide. A simple tuner can be bought for around 50 dollars whereas a more expensive alternative with more comprehensive software will cost upwards of 100 dollars.

With portability becoming more and more of an issue with today's consumers, a USB television tuner is a great solution to watching television from your computer.

Digital Projector Guide- Some tips for Digital Projectors

                     Digital projectors are equipments of modern technology. These are used to convert image data directly from the computer onto a screen via lens system. Digital projectors provide visualization of data that is actually stored in a computer for presentation. These projectors enable the viewers to watch moving images from a DVD, digital versatile disc player. Advertisers or sellers also use these projectors to give demonstration of products to a large number of customers. It can easily convert written documents onto an interactive whiteboard.

Digital projectors play an important role in the formation of home theater systems. These projectors use resolution of SVGA standard i.e. 800×600 pixels in expensive devices. Cost of digital projector is determined by its resolution as well as its brightness. If you're going to use it in large rooms or big conference halls its brightness should be from 1,000 to 4,000 ANSI lumens.

First digital projectors, Eidophor projectors were introduced in 1950. Eidopher projectors used an oily surface in a rotating disk with light shining through it and employed an electron beam to disrupt oil in a specific manner. Eidophor projectors were not able to produce colors. Nowadays there are several high quality models of digital projectors are available in market so Eidopher projectors are less common.

Following four technologies are used in digital projectors:



High intensity CRT

LCD projectors using LCD light gates

Texas Instruments' DLP technology

Eidophor oil-film projectors (obsolete)

At present LCD projectors use Texas Instruments' DLP technology whereas the high intensity CRT devices are suitable for enduring installations. Entire working of cathode ray tube digital projectors is like CRT television set. These projectors may be configured with one RGB color tube that has three colors red, green and blue with a single lens, one black & white tube with a rotating color wheel or three RGB color tubes with three lenses.

Projectors having cathode ray tubes are usually bulky thats why these are the best projectors for fixed installations.

LCD digital projectors are portable and lighter enough in comparison to CRT and can be easily shifted from one place to another. These are very much popular and available in various shapes and sizes. CRT and LCD digital projectors come under the category of transitive projectors.

Reflective projectors are the superior digital projectors that provide high quality images. These are affordable and offer next level of entertainment. Everyone can enjoy home theater applications with the help of digital projectors.

What is Computer Virus?

A computer virus is an executable program. Depend on the nature of a virus, it may cause damage of your hard disk contents, and/or interfere normal operation of your computer.

By definition, a virus program is able to replicate itself. This means that the virus multiplies on a computer by making copies of itself. This replication is intentional; it is part of the virus program. In most cases, if a file that contains virus is executed or copied onto another computer, then that computer will also be "infected" by the same virus.

A virus can be introduced to a computer system along with any software program. For Internet users, this threat can come from downloading files through FTP (file transfer protocol), or referencing email attachments. (Please refer to our web page on Handling Email's File Attachments for details.)

When a virus is introduced to a computer system, it can attach itself to, or sometimes even replace, an existing program. Thus, when the user runs the program in question, the virus is also executed. This usually happens without the user being aware of it.

A virus program contains instructions to initiate some sort of "event" that affects the infected computer. Each virus has an unique event associated with it. These events and their effects can range from harmless to devastating. For examples:

·         An annoying message appearing on the computer screen.

·         Reduced memory or disk space.

·         Modification of data.

·         Files overwritten or damaged.

·         Hard drive erased.

Finding Your MAC Address On Wired And Wireless Network Cards

Over the past few weeks I have received quite a few e-mails about Ethernet cards, both wired and wireless, and more specifically, about Media Access Control (MAC) addresses. I think the main reason I've received so many questions about Ethernet cards and MAC addresses is people trying to secure their home wireless networks and their desire to use MAC address filtering. This type of filtering in wireless networks can be configured to allow or deny specific computers to use or attach to the wireless network, based on the MAC address.

My first thought was to write an article just about MAC addresses and wireless Ethernet. After thinking about it I decided to expand on this and go over some specific information about Ethernet cards and communication.

Different Ways Of Finding Your MAC Address And More
--------------------------------------------------
There are several ways of finding your Ethernet and communications protocol information. Many Ethernet card manufacturer's have proprietary software that can reveal this information but they work differently depending on the manufacturer. So we will use the Windows 2000 and XP "ipconfig" utility since this is available in the majority of Windows Operating Systems.

First, go to "start" -> "run" and type "cmd" without the quotes. Then hit the enter key. At the command line type "ipconfig /all", again without the quotes. Actually, just typing ipconfig without the /all will work but will only provide you with abbreviated information regarding your network cards. An example of what you might see by typing the "ipconfig /all" command is below with each item commented in green lettering:

Fault Tolerant And Highly Availability Computer Systems
----------------------------
There are several ways of finding your Ethernet and communications protocol information. Many Ethernet card manufacturer's have proprietary software that can reveal this information but they work differently depending on the manufacturer. So we will use the Windows 2000 and XP "ipconfig" utility since this is available in the majority of Windows Operating Systems.

First, go to "start" -> "run" and type "cmd" without the quotes. Then hit the enter key. At the command line type "ipconfig /all", again without the quotes. Actually, just typing ipconfig without the /all will work but will only provide you with abbreviated information regarding your network cards. An example of what you might see by typing the "ipconfig /all" command is below:

OutPut Of The "Ipconfig /All" Command
----------------------------------------------------------
Windows IP Configuration


Host Name . . . . . . . . . . . . : Home Computer
This is the name of your computer, typically defined during the windows installation. However, it can be changed after installation. 

Primary Dns Suffix . . . . . . . : domain.com
If your computer participates in a network such as a Microsoft Windows domain this item may contain the name of the domain. 

Node Type . . . . . . . . . . . . : Unknown
The Node Type may say Unknown, or peer-to-peer, or in some cases "hybrid". It is a setting that has to do with the Windows Internet Naming Services used in certain types of Windows domain networks. 

IP Routing Enabled. . . . . . . . : No
This setting determines if Windows XP or 2000 will function as an IP router. If you have two or more network cards you can setup your system to act as a router, forwarding communications requests from one network to another. Windows 2000 can be configured to do this in a pretty straight forward fashion; Windows XP will need a registry modification. 

WINS Proxy Enabled. . . . . . . . : No
WINS Proxy is another setting that is related to the "Node Type" we discussed earlier. It is normally not a required setting in a home or small office network, or newer types of Microsoft Windows domains. 

Ethernet adapter Wireless Network Connection 2: 
If you have multiple Ethernet (network) cards in your systems, as I do in this laptop, you will have multiple listings. This one happens to be the second Ethernet card, an internal wireless Ethernet card. 

Description . . . . . . . . . . . : Broadcom 802.11b/g WLAN
This is the description of the Ethernet card, usually the Name / Manufacturer and type of Ethernet card. In this case, it is a Broadcom wireless Ethernet card built into my laptop. 

Physical Address. . . . . . . . . : 00-90-4B-F1-6E-4A
And here we have the MAC address. The MAC address is a 48 bit hexadecimal code and is suppose to be a totally unique address. It is 48 bits because each number or letter in hexadecimal represents 8 bits. Hexadecimal numbers range from 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E, F. There are 6 alpha-numeric codes hence 6*8=48(bits). The first 3 codes identify the manufacturer of the card and the remaining codes are used to create a unique number. Theoretically there should never be a card with same MAC address on a local network. However, there are a few exceptions. There are software tools that allow you to change this code. In fact, this is a step some hackers take to attack other systems on a local network. I say local network because MAC addresses are not routable between network segments. By spoofing this address, you can impersonate another machine on the local network. Traffic that was bound for the intended target can be redirected to the hacker's machine. This is the address you would also use to populate a MAC address, or physical address table when setting up your wireless access point to support MAC address filtering. 

DHCP Enabled. . . . . . . . . . . : Yes
DHCP, or the Dynamic Host Control Protocol, if enabled means your computers IP address is being provided by a DHCP server on you network. The DHCP server could be your wireless access point, cable/dsl router, cable modem, or a server on your network. Also, if a DHCP server is not enabled on your network, your computers Operating System will auto generate a random IP address within a certain predefined range. This means you could network a group of systems together without having to manually assign the IP settings. 

IP Address. . . . . . . . . . . . : 192.168.0.117
This parameter provides you with your current IP address. The address listed above is what is called a "private" address. There are certain classes of IP addresses that have been set aside for private use. This means for your internal, local, or private network at home or office. These addresses are not, or should not, be routable on the Internet. The Internet routes what are called "valid" IP addresses. Your cable/dsl router or cable modem has a valid IP address assigned to its "external" network interface. The external interface may be your phone line or cable TV cable.

Subnet Mask . . . . . . . . . . . : 255.255.255.0
The Subnet Mask is a special number, or in some sense, filter, that breaks down your IP address, in this case private IP address, into certain groups. IP addresses and Subnet Masks can be a complicated matter and would take an entire article to go over. 

Default Gateway . . . . . . . . . : 192.168.0.254
The default gateway, the IP addresses listed above, is the IP address of the device that will route your request, such as when you try to browse a website, to the Internet. It is a bit more complicated than that though as gateways or routers can route traffic to various different networks, even other private networks. At your home or small office, this gateway most likely is your cable/dsl modem or router. 

DHCP Server . . . . . . . . . . . : 192.168.0.49
The DHCP server, remember we talked a little about this above, is the device that assigns your computer an IP address and other information. DHCP servers can assign all kinds of information such as; Default Gateway, Domain Name Servers (DNS), IP address, Subnet Mask, Time Server, and much more. 

DNS Servers . . . . . . . . . . . : 192.168.0.49, 64.105.197.58
DNS Servers are internal or external servers that resolve Fully Qualified Domain Names (FQDN), such as www.defendingthenet.com , to IP addresses. This is done because computers don't actually transmit your requests using the domain name, they use the IP address assigned to the FQDN. For most home or small office users, the primary DNS server is the IP address of your cable/dsl router. Your cable/dsl router than queries an external DNS server on the Internet to perform the actual resolution of the FQDN to IP address. The address 192.168.0.49 is an internal private device on my network whereas the 64.105.197.58 is an external public Internet DNS server and is present just in case my router has trouble performing the DNS resolution tasks. 

Lease Obtained. . . . . . . . . . : Sunday, March 19, 2006 6:38:16 PM
This information tells you when your computer received its IP address and other information from a DHCP server. You will notice it says "Lease Obtained", that is because most DHCP servers only lease the IP address to you from a pool of available address. For instance, your pool may be 192.168.1.1 through 192.168.1.50. So your DHCP server has 50 IP addresses to choose from when assigning your computer its IP address. 

Lease Expires . . . . . . . . . . : Wednesday, March 29, 2006 9:38:16 PM
When the IP address, assigned by the DHCP server, lease expires it will attempt to lease you the same or another IP address. This function can typically be changed on the DHCP server. For instance, on some fully functional DHCP servers, you can configure the Lease to never expire, or to expire within 1 day and so on. 

Why Are MAC Addresses So Important And How Do They Work
------------------------------------------------------
To jump back to MAC address for just a bit. You may think that IP addresses are the most important thing when it comes to network communication. The reality is, MAC addresses are very important because without them computers would not be able to communicate over Ethernet networks. When a computer wants to speak with another computer on a local network, it will make a broadcast request, or ask a question, of who owns a particular IP address. For instance, your computer may say "Who is 192.168.0.254". Using the information above, my default gateway is 192.168.0.254 and will answer "I am "00-90-4B-F1-6E-4A" 192.168.0.254". It sends back its MAC address. That MAC address then goes into what is called a Address Resolution Protocol (ARP) table on your computer. You can see this information by going to the command prompt like you did above and typing "arp –a". You will get information like the following:


Internet Address Physical Address Type
192.168.0.49 00-12-17-5c-a2-27 dynamic
192.168.0.109 00-12-17-5c-a2-27 dynamic
192.168.0.112 00-0c-76-93-94-b2 dynamic
192.168.0.254 00-0e-2e-2e-15-61 dynamic

How A Hacker Can Use MAC Addresses In An Attack
----------------------------------------------
You will notice the IP addresses and to the right of them the MAC addresses. Without this information, without the MAC address, you would not be reading this article right now. MAC addresses are not routable like IP addresses. They work on your local or private network. However, devices on the Internet perform the same tasks. Routers and switches maintain a list of their peer devices MAC address just like your computers and devices on your home or office network. I mentioned above that MAC addresses can be changed in order to redirect requests. For instance, if I were on your office network and you had an internal web server that took personal information as input, I could tell your computer to go to my laptop for the web site by broadcasting my MAC address tied to the real web servers IP address. I would do this when you computer asked "Who is the "Real Web Server"". I could setup a fake web server that looks just like the real thing, and start collecting information the real web server would normally collect. You can see how dangerous this can be.

Conclusion
-----------
There are several other easy ways you can find your MAC address but they can be a little confusing if you have more than one internal network card. Most external USB, or PCMCIA wired and wireless Ethernet cards have their MAC address printed on them. In cases where the wired or wireless network card are inside your computer, such as in laptops, the MAC address is sometimes printed on the bottom of the laptop. Even Desktop systems cards that are inserted in PCI slots have the MAC address printed on the Ethernet card.

You may reprint or publish this article free of charge as long as the bylines are included. 

Original URL (The Web version of the article)
------------
http://www.defendingthenet.com/NewsLetters/FindingYourMACAddressOnWiredAndWirelessNetworkCards.htm

About The Author
----------------
Darren Miller is an Information Security Consultant with over seventeen years experience. He has written many technology & security articles, some of which have been published in nationally circulated magazines & periodicals. If you would like to contact Darren you can e-mail him at Darren.Miller@defendingthenet.com. If you would like to know more about computer security please visit us at http://www.defendingthenet.com. 

How to recover lost photos

t happens all too often. You're downloading your latest snaps from your digital camera, and the computer freezes. After you restart and try again, there appear to be no pictures in the camera. Or perhaps the photos were on your hard drive and you deleted them accidentally, or you didn't have a backup and your hard drive failed. 

Whatever the cause, there is no reason to panic. The computer may no longer be able to find your pictures, but it's unusual for a fault to completely wipe them from the storage card or disk. With the aid of some inexpensive data recovery software, you're almost certain to be able to get your photos back. 

There are many data recovery programs on the market, but for photo recovery I strongly advise using software specifically designed to recover digital images. This kind of software has several benefits, not least the ability to show a preview of every recovered image. Often, data recovery tools find files that look like they might have been a digital image, but aren't. The preview feature saves you wasting time recovering files that turn out to be junk. 

Another advantage of specialised photo recovery software is that it looks only for photo image file types. It knows what JPEG and other image files look like on disk. This improves the chances of a successful recovery, and reduces the number of junk files that are found. 

Modern data recovery software is easy enough to use that anyone can do it. You just start the software and tell the program where the drive containing the missing images is. The software scans the drive looking for the patterns that it recognizes as photo image files. When it has finished, it will display a list of files, with thumbnail images showing the content. All you have to do is select the photos you want to recover, and safe them to a safe place on your hard disk. 

Router - Transmitting Packets

In a previous article we discussed the basics of what a router did. We're now going to get into a more detailed, and yes technical, explanation of how packets are transmitted as well as a few other tech specs of how routers work. So put on your learning caps because you're in for a real mind bender. 

Internet data, whether it be in the form of a web page, a downloaded file or an email message, travels over what is called a packet switching network. Basically what happens is that the data is broken up into individual packets because there is only so much data that can be transmitted at one time. Each packet is about 1500 bytes long. Each packet contains quite a bit of information including the sender's address, the receiver's address and of course the information being sent which includes the order of each packet how it should be put back together so that the end user can make sense of the data. The packet is sent off to its destination based on what the router believes to be the best route to follow, which is usually the route with the least amount of traffic and if possible, the shortest route. Each packet may actually given a different route depending on conditions at the time, which in a high traffic network can change every second. By doing this, the router can balance the load across the network so that no one segment gets overloaded. Also, if there is a problem with one piece of equipment in the network, the router can bypass this piece of equipment and send the packet along another route. This way if there is a problem, the entire message will still arrive intact.

In conducting this process, routers have to speak to each other. They tell each other about any problems on the network and make recommendations on routes to take. This way, paths can be reconfigured if they have to be. However, not all routers do all jobs as routers come in different sizes and have different functions. 

There are what we call simple routers. A simple router is usually used in a simple small network. Simple routers simply look to see where the data packet needs to go and sends it there. It doesn't do much else. Slightly larger routers, which are used for slightly larger networks, do a little bit more. These routers will also enforce security for the network, protecting the network from outside attacks. They are able to do a good enough job of this that additional security software is not needed. The largest routers are used to handle data at major points on the Internet. These routers handle millions of packets of information per second. They work very hard to configure the network as efficiently as possible. These are stand alone systems and actually have more in common with supercomputers than with a simple server one might have in a small office. In our next instalment we'll look at how to actually trace the path that a message has taken and some examples of transmitting packets. 

How To Recover Lost Data

Computer files are a lot more important to some people than their lives because it represents their whole life's work and achievement. There are people who rely on their computers for almost everything, from their daily schedules, business and personal files and what have you. The possibility of losing their computer data is thus a horrifying thought for them.

Even a student who uses his computer to store assignments, research papers and other school data will be dismayed at the though of losing such files. What more for a computer dependent entrepreneur who relies on his computer for the day to day existence of his business. Losing computer data for both types of computer users would mean a catastrophe because once lost, computer data can no longer be recovered.

However, technological advancements have made data recovery possible depending on a lot of factors. For one, computer users are advised to make back ups of their computer data to make sure they would not be caught red handed when computer data is destroyed. For some who hold very important computer data, the back up itself should even be further backed up to make sure there is a way of recover lost data.

Fortunately, there are companies who offer data recovery services in case of an unforeseen disaster like corruption of files or crashing of a computer hard drive. People who store very important data in their computers need to have back ups but in any case, they should be acquainted with a computer company that can offer them fast and efficient services for the recovery of their lost computer data

It is thus pertinent that computer users have a way of knowing where to contact computer companies who can recover lost data for them no matter how such data was lost. There are various ways of losing precious data and one of those is carelessness. People take for granted that computers are very fast and efficient machines they can accidentally command their computers to lose or delete data in a flash.

The widespread use of internet has also been responsible for thousands of computer crashes all over the world because of viruses that attack computer hard drives. There are plenty of technical reasons why data is lost. Added to that are unforeseen disasters like fire or other calamity.

Computer users who have backed up their lost data but who discover that their back ups do not work still have a recourse. Rest assured that there are companies and software that can recover your computer files efficiently and quickly to minimize your potential losses.

Companies providing data recovery are equipped with technical people who around the globe and are more than capable of bringing back lost data. You just have to be able to know them beforehand so that when your computer data gets lost or destroyed then you have immediate access to their services. 

Wireless Networks: How Do They Work?

Wireless networks use radio waves instead of wires to transmit data between computers. Here's how:

The Binary Code: 1s and 0s

It's well known that computers transmit information digitally, using binary code: ones and zeros. This translates well to radio waves, since those 1s and 0s can be represented by different kinds of beeps. These beeps are so fast that they're outside the hearing range of humans.

Morse Code: Dots And Dashes

It works like Morse code, which is a way to transmit the alphabet over radio waves using dots (short beeps) and dashes (long beeps). Morse code was used manually for years via telegraph to get information from 1 place to another very quickly. More importantly for this example, though, it is a binary system, just as a computer system is.

Wireless networking, then, can be thought of as a Morse code for computers. You plug in a combined radio receiver and transmitter, and the computer is able to send out its equivalent of dots and dashes (bits, in computer-speak) to get your data from here to there.

Wavelengths And Frequencies

You might wonder how the computer can send and receive data at high speed without becoming garbled nonsense. The key to wireless networking is how it gets around this problem.

First, wireless transmissions are sent at very high frequencies, which allows more data to be sent per second. Most wireless connections use a frequency of 2.4 gigahertz (2.4 billion cycles per second) -- a frequency similar to mobile phones and microwave ovens. However, this high frequency produces a wavelength that is very short, which is why wireless networking is effective only over short distances.<

Wireless networks also use a technique called "frequency hopping." They use dozens of frequencies, and constantly switch among them. This makes wireless networks more immune to interference from other radio signals than if they transmitted on a single frequency.

Internet Access Points

The final step for a wireless network is to provide internet access for every computer on the network. This is done by a special piece of wireless equipment called an access point. An access point is more expensive than a wireless card for 1 computer, because it contains radios capable of communicating with around 100 computers, sharing internet access among them. Dedicated access points are necessary only for larger networks. With only a few computers, it is possible to use 1 of them as the access point, or to use a wireless router.

Industry Standards

Wireless equipment from different manufacturers can work together to handle these complex communications because there are standards which guide the production of all wireless devices. These standards are technically called the 802.11. Because of industry compliance with these standards, wireless networking is both easy to use and affordable today.

Wireless Is Simple To Use

If all this talk of frequencies has you worried -- relax. Wireless networking hardware and software handle all of this automatically, without need for user intervention. Wireless networking, for all its complicated ability, is far simpler to use than you might expect. 

High Definition Tuners

High definition TV tuners or HDTV tuners are designed to receive high definition programs by connecting to an external antenna. HDTV tuners will not only show movies and DVD's at high definition, but will improve the viewing of normal TV. It is because of the improved definition or color and picture quality of DVD's and programs that make HDTV tuners very popular with viewers.

Television sets often come with HDTV tuners already built into them, these are called integrated HDTV's. If you are considering buying an external high definition TV tuner for your television, make sure that your TV set is HDTV compatible. A separate tuner may also be needed. This can be either a cable or satellite box for watching high definition programs.Most people have heard that there is a mandate on televisions to make integrated HDTVs. This is not entirely correct. Certain televisions that are for sale after a certain date will be required to have built in tuners. The tuners required won't be HDTV. The mandate is actually referring to ATSC tuners. It is not even necessary that TV's be able to display HDTV resolutions without either an internal or external tuner. This new mandate will not apply to plasma and front projectors. The mandate will not take effect for some time. Until then there will be no change in television manufacture or tuners.

It is important to ask about features of high definition TV tuners before making a choice. If you are not sure what some of the features are, ask for clarification. Make sure that your television is compatible, HDTV tuners may not work with older televisions. Ask your cable or satellite company weather they support high definition TV, as many people find out later down the road that they cannot receive HDTV programs through cable or satellite.

Ask about what kind of warranties are available and what parts they actually cover before buying. External high definition TV tuners are quite reasonably priced. Prices start at around $150. If you are on a budget, make sure not to buy cheaply made appliances. Always wait for specials or price reductions on reliable brands.One of the most popular brands available is the Samsung SIR-T451. This one is ideal for high definition programming on any high definition TV compatible television. There are many more HDTV tuners available on the market. By doing a quick search on your favorite search engine, you will be able to find a HDTV tuner that will fit both your budget and your TV's requirements.