How to Fix DNS or Cannot Find Server Error

All of us, who have used the Internet have come across DNS error 'cannot find server'. Why is it, that we get this error? Let's get an answer.

I had just logged onto the Internet, but I was not able to reach the page I was looking for, as I kept getting the DNS error - cannot find server. I tried again and again, but in vain. That is when a friend suggested, I talk to my Internet service provider. They were also not able to help me. That is when I decided to take the issue in my hand. And I found out, that the DNS error of not being able to find server is, more often than not, your computer's inability to make a two-way connection to the Internet. If you have had an interrupted connection to the Internet, then the issue lies with your personal computer itself. All said and done this error will restrict you from using Internet technology to the fullest.

How to Fix DNS Error - Server Cannot be Found

The first step is to refresh the page, which failed to load. If the page reloads, then this was just a momentary lapse in service, which happens even to the best Internet service provider. If the problem is not resolved, you will need to follow the following steps.

• Check the page address you have typed into the address bar. There is a chance, that you may have misspelled the address. In most cases, an error in the URL address gives rise to this error message.
• Try to refresh the page, you will now be able to view the web page, you are looking for.
• If the above mentioned step, is not able to solve the problem, you will have to go to connection settings. You will have to ensure, that the settings, match with those of the Internet service provider or that of the local area network.
• To do this you will have to click on the tools menu on the tool-bar, then click on Internet options. There you will come across the Connections tab, under which you will notice Settings.
• Now you can try to refresh the page and check, if you are able go to the web page you have been looking for.
• If this option does not work either, then click on the link 'Detect Network Settings' on the Internet Explorer page, which accompanies the error message to let Windows try to find an optimum connection to the Internet.
• Now again refresh the page.
• You can download DNS server error software off the Internet, if all the above options do not work.
• These software are free on some of the websites, and they would be able to identify the problem. A PS3 DNS error problem can also be corrected by downloading this software.

In case you persistently face the problem DNS error server cannot be found, you may have to put in a request for a new IIS Certificate. Depending on the situation you may have to renew the existing license. The certificate will be issued to you or you will be asked to check back within 10 days. In case the policy module has been set to automatically issue the request, you will not have to put in a request yourself. Apart from all these steps for DNS error cannot find server, you may want to check the modem or router for any sort of irregularities. In case there are some lights flashing or some of them are not seen at all, which ideally should be on, then the server error is most probably not correctable on your computer. You will have to get in touch with your Internet service provider to rectify the problem.

How to Find a MAC Address

What is a MAC address and why is it essential that it be located? How to find it on your computer? If you are configuring your router, these questions are bound to come to your mind.

Computer networking is a very precise form of applied science and to understand it completely, you need to study many of its intricacies. One of the things that you need to know while setting up your home Ethernet network or home wireless network, you will need to know what are known as MAC addresses. You need these addresses, when setting up a wireless network and configuring your router. One way of securing your wireless network is to use filters based on these addresses, to restrict access.

What is MAC Address?

The short form - MAC stands for Media Access Control. A Media Access Control address is assigned as a unique identifier to every network adapter fitted in any device that is connected in an Ethernet or wireless network. Every device connected to the Internet has an inbuilt network interface card that enables its connection to an Ethernet network or wireless network. Thus every device with a network adapter like your own laptop computer can be identified by its MAC number.

The address, also known as physical address or hardware address is stored in the read only memory of the network interface card. According to the IEEE 802 standard, a convention is set for how these addresses are written. The number is written as a string of six hexadecimal numbers, separated into six groups with two numbers in each. They can be retrieved through the installed operating system on a device.

How to Find It?

Here are ways in which you can retrieve the address on any operating system.

On Windows

If you are using a computer operating system of the Windows family (including Windows XP, Windows Vista and Windows 7), to find the MAC address, you will need to open 'Command Prompt', which can be located in Start > Accessories on Windows Vista and Windows 7 machines. Once you open the command prompt, first type in 'cmd'. Then type in 'ipconfig/all'. This will display a list of details which includes the address. It will be listed as 'Physical Address'. It can be identified as a 12 digit hexadecimal number separated in groups of two each and with dashes in between.

On a Mac

To find the address on a Mac OS X snow leopard based machine, select 'System Preferences' from the Mac Menu. Among the many icons that you will see in the windows that opens next, click on 'Network' icon. A windows will open with various tabs. To get address, click on the tab that has 'Ethernet' written on it (if you have an ethernet connection) and it will be displayed as 'Ethernet ID'. To find the wireless network card or Airport card address, click on the Airport tab. You will see its address displayed below as AirPort ID.

On Linux

On any Linux system, to find the MAC address, you must first be signed in as root. Once you are signed in as root user, type 'ifconfig -a ' in the command terminal. You will see a lot of information displayed below. The number listed as 'HWaddr' (Hardware Address) is the address of that computer's network adapter.

All you have to do is follow the simple instructions explained above and you will be able to retrieve the information you need. Once you find the addresses of the computers that are going to be connected in your home network and add them to the filter list, only they will be granted exclusive access to the network. That way, you can prevent unauthorized access to your network.

Coaxial Cable Connectors

With the advancing technology in the modern world today, wherever you look around, you see wires and cables connecting people's lives. Doubtlessly, we call it a wired world and the truth is that we cannot do without these connectors now! Coaxial cable connectors are dual-layered electrical cables, with an insulating layer on its inside and tubular layer on the outside. But there are times when these electrical cable connectors differ from one another due to its make and wide range of varieties. So, let us first see its definition, and later, let's see what are the different types and forms available in the market, which are used to connect a variety of home appliances and electronic devices in our daily lives.

What are Coaxial Cable Connectors

A cable that shares a common axis consisting of two conductors is called a coaxial cable. The conductor present inside the cable is generally a straight wire (solid or stranded) and the conductor present outside is a shield (braided or foil). These cable connectors are practically used as a transmission line for transmitting video and radio frequency data and measurement signals obviously in applications such as radio receivers, transmitters, Internet (for networking), TV and so on. Moreover, the best part about coaxial cables is that the electromagnetic field which carries the signals simply exists between the outer and inner conductors. This means, these cables can be connected next to any sort of metal object without the concern of any type of signal (power) loss. They also reject the entry of external electromagnetic interference via signal transmission.

Types of Coaxial Cable Connectors

A coaxial cable is also termed as coax cable or just coax. As the built of a coaxial cable has been already mentioned, it is the most popular cable as a transmission line in terms of high-frequency signals, like the ones for computer networking and cable television transmission. With this take, let us further look at some information on coaxial cable types.

Hard Line Coaxial Cable: A hard line cable is used for broadcasting and radio communications and has a copper plated aluminum conductor as a building material in its core. The outer shields are made of silver or gold materials.

RG-6 Coaxial Cable: The built of the outer and inner part of RG-6 is simply separated by a copper braided dielectric insulator. There are several kinds in RG-6 as well, like the plain RG-6 expended for internal/external wiring. And there is waterproof flooded coax used in underground wiring. RG-6, on regular basis, has many commercial as well as residential uses.

Radiating Coax Cable: Almost similar to hard line coax, the built of these electrical cable connectors has slots cut into shields, that are specifically pitched for RF wavelength and radio frequency band.

Triaxial Cable: Triaxial cable has a construction wherein the single copper inside the core has three protecting shields, (two copper and one dielectric insulator) on its outside. These cables reduce signal leakage, transmission and external noise interference to a substantial level.

Twin-axial Cable: There is a pair of solid conducting wires at the core of these cables which are actually plastic-coated in nature. The outside is confined by two copper braids separated by some insulating material. The pair of coaxial cables at the core of the cable basically, carry two varying electric voltages.

Semi-rigid Coaxial Cable: This type is not flexible in nature, and has a solid conducting sheath confining the internal conductor. These connectors are expended in applications where microwave signals are garnered using scientific methods.

As mentioned before, coax (coaxial) cables are used for satellite connectivity and cable television transmission, they prove to be extremely effective for transmitting signals responsive to radio frequencies. The connectors are fitted at the terminal ends of the coax cables. Also, they are fitted in a screw-type style with needles at the center so that the contact is made with a female connector on any receiver appliance. The coax cable connectors are literally simple to attach to the cables, if you know how to install these cable connectors in the coax cables in the correct way. Here is a short procedure on the same.

How to Connect Coaxial Cable Connectors

Most of the coaxial connectors have a needle sticking out from its center to make contact with a female pin on a receiving device. So find the male and female coaxial connectors first. Next, check on the condition of the connectors whether they are damaged, needs a replacement, or they are corroded. Once you determine that, make a male connector from the piece of a cable and replace the old for new. To make this new piece of coaxial cable, you might have to strip out the covering on the outside to ½'' of wire. The stripping of the cable should be performed very carefully so that the outer wire mesh isn't damaged. Once the wire mesh is visible on the inside, expand it and strip off the final 3/8'' of the plastic coat placed at the end of the wire. This will give you an exposed center conductor. Now press the ends of the wire properly to ensure it passes through the screw-form of the connector. Also, check that there is no plastic left behind, on the center conductor and covering shield across the fitted dual-layered cable connector. The final action is to place the center conductor at the center of the female pin and screw the newly fitted connector firmly, for completing the entire procedure.

Coaxial connectors are thick sheath coax cables, transmitting signals down the center of the conductor to various appliances, also taking care of the noise cancellation factor. With this information, you now know how to connect the connectors to the cable and also know how to install them to desired devices.

Wireless Bridge Vs. Access Point

Wireless bridges and access points offer radio link connectivity over a computer network, but they are structurally and functionally designed to serve slightly different purposes. The wireless bridge vs access point comparison presented in this article is aimed at clarifying the differences between the functionality and applications of both devices.

Setting up a vast wireless network for a corporate office space requires the installation of many networking devices, that facilitate connectivity over the entire network. Two such devices are 'Wireless Bridges' and 'Wireless Access Points'. Since both have overlapping areas of functionality, there seems to be confusion regarding how they differ from each other.

What are Wireless Bridges?

Let me first define what is meant by a 'Network Bridge'. A computer network tends to be divided into various segments that need to be integrated together. A network bridge connects such divided network segments together, facilitating data sharing. Before the advent of Wi-Fi technology, network bridges were connected through wired ethernet cables. Specifically, in context of the OSI model, network bridges connect segments on layer 2 (data link layer).

These are intelligent devices compared to hubs and repeaters, that control data flow to and fro, from the connected network segments. A wireless bridge performs the same function of linking network segments, but it does that through a Wi-Fi link, instead of a wired ethernet link. It can connect two networks together with a radio link, to facilitate connectivity and data transfer between them.

Such bridges may also be used to connect an ethernet network, with an access point or wireless router, for Internet connectivity. Using a 'Wireless Distribution System', bridges are set up to connect multiple networks. There are more than one types of wireless bridges, ranging from basic ones, which facilitate ethernet connectivity with a wireless access point, to ones that double up as a wireless access point and a bridge. That seems to be the source of confusion between the two devices.

What are Wireless Access Points?

As their name suggests, wireless access points primarily provide Internet access by connecting wireless devices with routers. They act as extenders of a Wi-Fi network, by directly providing Internet access over long distances. Popularly known as 'Wireless Hotspots', they are some of the most widely used networking instruments. Thus a wireless access point provides Internet and LAN connectivity to multiple devices simultaneously.

Some wireless access points also provide the functionality of a wireless bridge, by providing connectivity between two wireless networks. Modern access points can connect more than 200 wireless devices simultaneously. Some wireless access points are in fact wireless routers which directly provide Internet access, through connection with a modem.

Wireless Bridge Vs Access Point

The central point of difference between the two devices lies in their functionality. While wireless bridges are designed to integrate two physically separated networks through a radio link, an access point connects multiple wireless devices with a router. Thus, a wireless bridge connects two computer clusters together and a wireless bridge connects multiple devices with a single Internet connection simultaneously. A bridge can also be used to connect an existing ethernet network with an access point.

Though wireless bridges and access points were separately manufactured before, today a combination of these two devices is more popularly used. These devices offer both bridging and multiple device wireless connectivity. Therefore, the boundary between the functionality of both devices has become blurred. If you are thinking of buying a wireless access point/bridge device, make sure that you go for a 802.11n wireless networking standard based device, which offers the highest data transmission speed currently.

CCNA Certification Cost

The Cisco Certified Network Associate (CCNA) certification has helped several students secure high paying jobs in the field of networking. This article has information on CCNA certifications, like its cost and exam details.

CCNA is an industry accepted and reputed certification offered by Cisco Systems. When a candidate obtains such world-class certifications, employers are assured that the candidate has excellent knowledge of the concepts and fundamentals of networking. More over, a candidate obtaining such certifications is considered as an industry-ready professional, and that is why CCNA job salaries have been very impressive throughout the world.

CCNA Certification Details

CCNA certified professionals are considered to be experts in the installation and operation of a LAN, Wireless LAN and WAN and the Switched Network Services. These professionals make use of the Cisco compatible equipment in the installation and maintenance of infrastructure in companies they work for. To get CCNA certifications, you need to clear the ICND1 640-822 and ICND2 640-816 exams or a single 640-802 CCNA composite exam. Those who opt to study CCNA security should be able to give services like troubleshooting of network devices, installation of network and identification of threats to networks. This CCNA security certification requires you to clear the IINS 640-553 exam.

Some professionals opt for the CCNA voice certification which can help them get jobs like voice technology manager, voice engineer etc. This certification is also in demand like the CCN security one, and requires you to clear the IINS 640-553 exam. On the other hand, the CCNA wireless certified professionals are experts in configuring and implementing LAN's. For this particular certification, you need to clear the 640-721 IUWNE exam.

CCNA is an entry-level networking certification offered by Cisco. This is considered to be one of the best certifications for fresh graduates to start a lucrative career in the information technology (IT) sector. Generally, it is suggested that you have a networking background for getting this certification, though it is not mandatory. Those with networking skills will be able to understand and learn the course contents better. For other students, it takes anything between four to six months to prepare for the CCNA exam. Remember that this is one of the most widely accepted computer based exam for which you need to have analytical skills, mathematical ability, logical thinking skills and great presence of mind along with networking abilities to fare well. Taking mock tests and practicing solving multiple choice questions is necessary to clear the CCNA examination. After clearing the CCNA exam which is administered by the Pearson VUE, you become eligible for following jobs:

* Network security manager

* Network administrators

* Network engineers

Certification Cost

The CCNA certification expense would be $250. International candidates can convert the amount into their own currency to get an idea of how much exactly they will have to spend. If you wish to take the two separate CCNA exams, then you will have to pay $125 for each exam. The fees for the CCNP Composite (642-892) exam is $300. The Cisco CCNA certification expense is same worldwide and hence, there has been no discrimination regarding price in this context. For all those who are eager to know how much the overall certification cost, knowing that cost of books and study material might not be entirely included in the above mentioned fees. Also students will have to bear expenses of traveling to the test venue themselves. The certification requires renewal after every three years and the cost for the same is also not included in the CCNA certification expense. You can also consider the A+ certification which has great job openings in today's job market.

So, these were some vital details about the CCNA certification. Many students from varied backgrounds eager for a career in networking are taking the can exams. To fare well in the exam and become successful in this career, you need to have patience and hard-working ability. Good luck!

Computer Network Topology

Network topology is the physical interconnection of the elements of a computer network. Broadly there are two kinds of elements in computer networks - node and link. Topology is the two dimensional geometric shape or structure formed in a network with its nodes being apices and the links being the sides. This shape may or may not match with the actual physical design of the devices on the computer network. Even in identical topologies, distances between nodes, physical interconnections, information transmission rates, and/or signal types may vary from each other. Exclusively in Local Area Networks (LAN) both a physical topology and a logical topology are homologous with respect to links and nodes.

Broadly network topology can be categorized into two types:

• Physical
• Logical

Physical topologies are commonly:

• Bus - nodes occurring on both sides of a single line of link; it can be linear with two end points or, distributed with multiple end points.
• Star - multiple nodes around being connected in radiating fashion to a central node.
• Tree (hierarchical) - links being branched into multiple levels to connect nodes.
• Ring - each node being connected to adjacent two nodes, forming a close ring.
• Mesh - each node connected to other nodes in the network:
• Partially connected -each node being connected to at least one node of the network,
• Fully connected (sometimes known as fully redundant) - each node connected to at least two adjacent nodes in the network.

Types of logical topologies are analogous to the types of physical topologies. Yet the links among nodes are defined by the actual direction of flow of data among the nodes. Actual physical connectivity between the nodes of logical topology may or may not exist.

There also exists signal topology. It is defined by the path of actual signal transmission among the nodes. For a given point of time, signal topology is the real mapping of connectivity among the nodes.

Often signal topology is used interchangeably with logical topology. But they are quite different indeed. Signal topology is the geometry of signal transmission, while logical topology is the map of data transmission. The two are always not analogous.