Showing posts from May, 2012

A+: More on TCP/IP Configuration

TCP/IP Alternate Configuration
The Alternate Configuration tab is used to set up a different configuration for use when a DHCP server is not available or when a different set of user-configured settings are needed, as when a laptop is being used at a secondary location. By default, automatic private IP addressing (APIPA) is used when no DHCP server is in use. APIPA assigns each system a unique IP address in the 169.254.x.x range. APIPA enables a network to perform LAN connections when the DHCP server is not available, but systems using APIPA cannot connect to the Internet.  When you see a 169.254 series address, DHCP has failed, and should be repaired.

You can also use the Alternate Configuration tab to specify the IP address, subnet mask, default gateway, DNS servers, and WINS servers. This option is useful if this system is moved to another network that uses different IP addresses for these servers.

TCP/IP User-Configured IP and DNS Addresses When a DHCP server is not used, the Gen…

A+: Installing Network Protocols

Before a network connection can function, it must be properly configured. Here;s some terminology you'll need:

The IP address identifies a computer or device on the network and must be unique. To make sure it is unique, it can be auto-assigned by a DHCP server.

The DNS configuration identifies the DNS (Domain Naming System) and speficies one or more DNS servers. It is the 'White Pages' of the Internet, providing the IP address when requested for any web address, host name or domain name.

A Gateway here is a logical device (the term is also used for a hardware device) which identifies the IP address of a device which connects a computer or network to the Internet or another network. It is the same address for all computers and devices on the same network.

The WINS configuration maps IP addresses to NetBIOS computer names, and was used with NT4 and earlier versions of Windows. It is obsolete.

Installing Network Protocols in Windows Depending upon the network protocol you w…

A+: Switches and Hubs for LANs, Repeaters, Bridges, and Routers for WANs

Hubs connect different computers with each other on an Ethernet network based on UTP or STP cabling. A hub has several connectors for RJ45 cabling, a power source, and signal lights to indicate network activity. Most hubs are stackable, meaning that if you need more ports than the hub contains, you can connect it to another hub to expand its capabilities.

A hub is the slowest connection device on a network because it splits the bandwidth of the connection among all the computers connected to it. For example, a five-port 10/100 Ethernet hub divides the 100 Mbps speed of Fast Ethernet among the five ports, providing only 20 Mbps of bandwidth to each port for Fast Ethernet and 10/100 adapters, and only 2 Mbps per port for 10BASE-T adapters. A hub also broadcasts data to all computers connected to it.

A switch resembles a hub but creates a dedicated full-speed connection between the two computers that are communicating with each other. A five-port 10/100 switch, for example, provides the …

A+: Wireless Ethernet (WLAN) Configuration

Most home and small-business networks using encryption will use a pre-shared key (PSK). When a pre-shared key is used, both the wireless router or access point and all clients must have the same PSK before they can connect with each other. WPA and WPA2 also support the use of a RADIUS authentication server, which is used on corporate networks.

Wireless Ethernet requires additional configuration compared to wired Ethernet, as shown below:

The SSID (Service Set Identifier) names the network. XP and later can detect SSIDs on unsecured ('open') networks.

The Channel specifies a predefined frequency for all stations to use. Since the Wireless Zero Configuration service of XP, WIndows will determine the channel to use automatically, but if ad-hoc (peer-to-peer) configurations are used or if vendors software is used for configuration, a manual assignment may be needed. Only channels 1, 5, 11 and 14 do not overlap with other channels, and channel 14 can't be used in North America.

A+: Installing Network Interface Cards

Although many recent computers include a 10/100 or 10/100/1000 Ethernet port or a Wireless Ethernet (WLAN) adapter, you often need to install a network interface card (NIC) into a computer you want to add to a network.

PCI, PCI Express
To install a Plug and Play (PnP) network card, follow this procedure:

Turn off the computer and remove the case cover.Locate an available expansion slot matching the network card’s design (most use PCI, but some servers and workstations might use PCI-X or PCI Express).Remove the slot cover and insert the card into the slot. Secure the card in the slot.Restart the system and provide the driver disk or CD-ROM when requested by the system.Insert the operating system disc if requested to install network drivers and clients.The IRQ, I/O port address, and memory address required by the card will be assigned automatically.Test for connectivity (check LED lights, use a command such as ping, and so on), then close the computer case.

Although USB network adapt…

A+: Connector Types

Most coaxial cables, including RG-58, RG-59, and RG-6 use a BNC (Bayonet Neill-Concelman) connector. RG-58 uses a T-adapter to connect to a 10BASE2 Ethernet adapter. RG-11 (Thicknet) cable is connected to an Ethernet card by means of an external transceiver, which attaches to the AUI port on the rear of older Ethernet network cards. The transceiver attaches to the cable with a so-called “vampire tap.”

10BASE-T, 100BASE-T, and 1000BASE-T Ethernet cards using copper wire all use the RJ45 connector, as do newer token-ring, some ISDN and most cable Internet devices. DSL devices often use the RJ11 connector, as do dial-up modems.

To attach a cable using RJ11 or RJ45 connectors to a network card or other device, plug it into the connector so that the plastic locking clip snaps into place; the cable and connector will fit together only one way. To remove the cable, squeeze the locking clip toward the connector and pull the connector out of the jack. Some cables use a snagless connector; sque…

A+: Fiber Optic and Coax Cables

Fiber-optic cabling transmits signals with light rather than with electrical signals, which makes it immune to electrical interference. It is used primarily as a backbone between networks.

When Ethernet is run over fiber-optic cables, the letter F is used in place of T (twisted pair) in the name. For example, 10BASE-F is 10 Mbps Ethernet running on fiber-optic cable, 100BASE-F is 100 Mbps Ethernet running on fiber-optic cable, and so on.

Fiber-optic cable comes in two major types:

    • Single-mode— Has a thin core (between 8 and 10 microns) designed to carry a single light ray long distances.

    • Multi-mode— Has a thicker core (62.5 microns) than single-mode; carries multiple light rays for short distances.

Fiber-optic cabling can be purchased prebuilt, but if you need a custom length, it should be built and installed by experienced cable installers because of the expense and risk of damage. Some network adapters built for servers are designed to use fiber-optic cable. Otherwise, …

A+: Cable and Connector Types

Network cards are designed to interface with one or more types of network cables. UTP and STP cable can be purchased in prebuilt assemblies or can be built from bulk cable and connectors. Four major types of network cables are:

    • Unshielded twisted pair (UTP)
    • Shielded twisted pair (STP)
    • Fiber-optic
    • Coaxial (rare now)

USB, serial (RS-232) null modem and parallel (LPT) crossover cables can be used with direct parallel or direct serial connections (also known as direct cable connection), which are special types of two-station networking included in Windows that use standard network protocols but do not use network cards. Infrared (IR) ports built into many notebook computers can also be used with direct serial connection.

Unshielded twisted pair (UTP) cabling is the most common of the major cabling types. The name refers to its physical construction: four twisted pairs of wire surrounded by a flexible jacket.   It comes in various grades, of which Category 5e is…

A+: Wireless LAN compatibility chart

------         ---        ---
802.11a5 GHz54 MbpsReq dual-mode hw (a/b or a/g) 802.11n supports 5GHz
802.11b2.4 GHz11 Mbps802.11g
802.11g2.4 GHz54 Mbps802.11b, 802.11n
802.11n2.4 GHz (std)600 Mbps max802.11b, 802.11g (802.11a on WLANs also supporting 5GHz)
5 Ghz (opt)(300 Mbps typ max)

A+: Other popular protocols

Bluetooth: Bluetooth is a short-range low-speed wireless network primarily designed to operate in peer-to-peer mode (known as ad-hoc) between PCs and other devices such as printers, projectors, smart phones, mice, keyboards, and other devices. Bluetooth runs in the same 2.4GHz frequency used by IEEE 802.11b, g, and n wireless networks, but uses a spread-spectrum frequency-hopping signaling method to help minimize interference. Bluetooth devices connect to each other to form a personal area network (PAN).

Some systems and devices include integrated Bluetooth adapters, and others need a Bluetooth module connected to the USB port to enable Bluetooth networking.

Infrared:  Infrared is a short-range, low-speed, line-of-sight network method that can be used to connect to other PCs, PDAs, or Internet kiosks. Infrared networking is based on the Infrared Data Association (IrDA) protocol. Some laptops include an integrated IrDA port. IrDA can also be used for printing to printers that include an…

A+: Network Topologies and Ethernet

The physical arrangement of computer, cables, and network devices is referred to as a network topology. There are four different types of network topologies:

    • Bus— Computers in a bus topology share a common cable. Connections in this topology are made largely with coaxial 10BASE2 and 10BASE5 cables. The network goes down if a single computer on a bus-topology network fails, but the other network types stay up if one or more computers fail.

    • Star— Computers in a star topology connect to a central hub or switch (wired) or access point (wireless). This topology is used by 10BASE-T (10 Mbps Ethernet), 100BASE-T (Fast Ethernet), and 1000BASE-T (Gigabit Ethernet) Ethernet networks and by Wireless Ethernet (Wi-Fi) when configured for the default infrastructure mode.

    • Ring— Computers in a ring topology either connect as a physical ring, for example FDDI networks; or a logical ring, as is the case with Token Ring networks.

    • Peer-to-peer (Mesh)—Computers in a peer-to-peer or…

A+: Ports

For two computers to communicate they must both use the same protocol. In order for an application to send or receive data it must use a particular protocol designed for that application, and open up a port on the network adapter to make a connection to another computer. For example, let us say you wished to visit You would open up a browser and type The protocol being used is HTTP, short for Hypertext Transfer Protocol. That is the protocol that makes the connection to the web server: The HTTP protocol would select an unused port on your computer (known as an outbound port) to send and receive data to and from On the other end,’s web server will have a specific port open at all times ready to accept sessions. In most cases the web server’s port is 80, which corresponds to the HTTP protocol. This is known as an inbound port.

If the port is blocked, the service it depends on will fail.


A+: TCP/IP Applications and Technologies

TCP/IP actually is a suite of protocols used on the Internet for routing and transporting information. Here are   some of the application protocols that are part of the TCP/IP suite, as well as some of the services and technologies that relate to TCP/IP.

ISP: An ISP (Internet service provider) provides the connection between an individual PC or network and the Internet. ISPs use routers connected to high-speed, high-bandwidth connections to route Internet traffic from their clients to their destinations.

HTTP/HTTPS: Hypertext Transfer Protocol (HTTP) is the protocol used by web browsers, such as Internet Explorer and Netscape Navigator, to access websites and content. Normal (unsecured) sites use the prefix http:// when accessed in a web browser. Sites that are secured with various encryption schemes are identified with the prefix https://.   Most browsers connecting with a secured site will also display a closed padlock symbol onscreen.

SSL: Secure Socket Layers (SSL) is an encryption t…

A+: LANs, Internet Connectivity and Network Protocols

A LAN is an ideal way to provide Internet access to two or more users. However, a LAN by itself cannot connect to the Internet. Two additional components must also be used with a LAN to enable it to connect to the Internet:

    • An Internet access device— This could be a dial-up modem, but more often a broadband connection such as DSL, cable, or satellite is used.

    • A router—This device connects client PCs on the network to the Internet through the Internet access device. To the Internet, only one client is making a connection, but the router internally tracks which PC has made the request and transmits the data for that PC back to that PC, enabling multiple PCs to access the Internet through the network.

As an alternative to a router and modem or codec, some small networks use a gateway, which is a PC configured to share its Internet connection with others on the network. Windows 2000 and later versions support this feature, known as Internet Connection Sharing. Note that wirele…

A+: Broadband Internet Services (DSL, Cable, Satellite)

Broadband Internet service is a blanket term that refers to the following Internet access methods: digital subscriber line (DSL), cable, and satellite. All of these methods provide bandwidth in excess of 300Kbps, and current implementations are two-way services, enabling you to use your telephone while accessing the Internet. Other types of broadband Internet service, including direct wireless (using microwave transceivers) and powerline, are not part of the A+ Certification exam domains, but you might encounter them in some areas.
DSL (Digital Subscriber Line), like ISDN, piggybacks on the same telephone line used by your telephone and fax machine, but it differs from ISDN in many ways. Like ISDN, DSL requires a high-quality telephone line that can carry a digital signal, but unlike ISDN, DSL is designed strictly for Internet access.
When it comes to connection speed, DSL leaves BRI ISDN in the dust. There are two major types of DSL: ADSL (Asynchronous DSL and the predominant…

A+: ISDN, Hardware & Connections

ISDN (Integrated Services Digital Network) was originally developed to provide an all-digital method for connecting multiple telephone and telephony-type devices. such as fax machines, to a single telephone line and to provide a faster connection for teleconferencing for remote computer users. A home/small office-based connection can also provide an all-digital Internet connection at speeds up to 128Kbps. Line quality is a critical factor in determining whether any particular location can use ISDN service. If an all-digital connection cannot be established between the customer’s location and the telephone company’s central switch, ISDN service is not available or a new telephone line must be run (at extra cost to you!).

The telephone network was originally designed to support analog signaling only, which is why an analog (dial-up) modem that sends data to other computers converts digital signals to analog for transmission through the telephone network. The receiving analo…

A+: Dial-Up Internet Service Providers and Connections

An Internet service provider (ISP) provides a connection between the user with an analog (dial-up) modem (or other connectivity device) and the Internet. ISPs that provide dial-up access have several modems and dial-up numbers that their customers can access. The ISP’s modems are connected to the Internet via high-speed, high-capacity connections.

An ISP can be selected from many different sources: • National companies • Local or regional providers • Specialized providers such as those that provide filtered, family-friendly access Choose an ISP based on its rates, its reliability, or special services (such as content filtration or proprietary content) that are appropriate to your needs. Creating a Dial-Up Connection Windows Vista creates dial-up networking (DUN) connections within the Network and Sharing Center window. Windows XP and 2000 create DUN connections within the same window that stores other types of network connections: • Windows XP stores all types of network conn…

A+: Analog Modem Installation

The method used for physical installation of the modem varies with the modem type. To install a PCI modem, follow these steps: Step 1. Take ESD precautions. (See Chapter 17, “Safety and Environmental Issues,” for details.)
Step 2. Open the system and locate an empty slot of the appropriate type.
Step 3. Remove the screw holding the slot cover in place.
Step 4. Remove the slot cover.
Step 5. Install the modem into the slot and fasten it into place with the screw previously used to secure the slot cover.
Step 6. Connect an RJ-11 telephone cable running from the telephone jack in the wall to the line connection.
Step 7. If desired, plug a telephone into the telco jack.
Step 8. Close the system and restart it.
Step 9. Install drivers as required. You can drive yourself crazy trying to make a connection with your modem if you plug the RJ-11 telephone cord into the wrong jack. There are actually three ways to make this mistake:
• Plugging the RJ-11 cord into the phone jack instead of the line or t…

A+: Internet connectivity and dial-up modems

One of the best reasons to create a network of any size is to provide access to the Internet.  Properly used, the term modem (modulator-demodulator) refers only to a device that connects to the telephone line and performs digital-to-analog or analog-to-digital conversions. However, other types of Internet connections such as satellite, wireless, DSL, and cable Internet also use the term modem, although they work with purely digital data; the proper term is codec (coder-decoder). When used by itself here, however, modem refers only to dial-up (telephone) modems. Dial-Up Modems and Internet Connectivity Until the late nineties, dial-up networking (DUN) had been the most common way for home and small businesses to connect to the Internet. Dial-up connections are often referred to as analog connections because the device used to make the connection is an analog modem, which connects to the Internet through an ordinary telephone line. Every time you connect to the Internet with a di…

A+: Peer-to-Peer

The network features built into Windows allow for peer servers: Computers can share resources with each other, and machines that share resources can also be used as client workstations. As with client/server networking, resources on peer servers can be accessed via universal naming convention or by mapping drive letters and printer ports on a client to server resources.

If mapped drive letters and printer ports are used in a peer-to-peer network, the same resource will have a different name, depending on whether it’s being accessed from the peer server (acting as a workstation) itself or over the network. 
In a simple two-station peer-to-peer network, each computer acts as a peer server to the other. One PC shares its external hard disk drive with another PC, which refers to the shared hard disk drive as F:\. The second PC  shares its printer with the first PC, which has mapped the shared printer to LPT2.
The peer server loads file and printer-sharing software to make printers and dr…

A+: Client/Server

The roles of each computer in a client/server network are distinctive, affecting both the hardware used in each computer and the software installed in each computer. In a client/server environment there are many advantages including centralized administration, better sharing capabilities, scalability, and possibly increased security.

Most departmental and larger networks are client/server networks. The networks controlled by Windows Server 2008 and 2003, Windows 2000 Server, and Novell NetWare servers are examples of client/server networks.

One example is a server with three workstations, each of which is using a different shared resource: One is using the server’s inkjet printer, one is printing to the server’s laser printer, and one is copying a file to the server’s RAID array.

Servers A server is a computer on the network that provides other computers (called clients or workstations) with access to resources, such as disk drives, folders, printers, modems, scanners, and In…

A+: Networking

A network is a group of computers, peripherals, and software that are connected to each other and can be used together. Special software and hardware are required to make networks work.
Two or more computers connected together in the same office are considered a LAN (local area network). LANs in different cities can be connected to each other by a WAN (wide area network). The Internet represents the world’s largest network, connecting both standalone computers and computers on LAN and WAN networks all over the world.
At one time, it was necessary to use a network operating system (NOS) such as Novell NetWare to enable networking. However, current operating systems, including Windows, include the components needed for networking.
Windows Vista, XP, and Windows 2000 include the following NOS features, enabling systems running these operating systems to be used either as network clients or as peer network servers: • Client software— Enables systems to connect with other netwo…

A+: More options for failing system devices with conflicts

If the device has a conflict with another device, you might be able to change the settings in the device’s Properties page/Resources tab. If the device is a legacy (non-PnP) device, you might need to shut down the system and reconfigure the card manually before you can use Device Manager to reset its configuration in Windows.

You can also use the Device Manager to disable a device that is conflicting with another device. To disable a device, follow these steps:

    Step 1. Click the plus (+) sign next to the device category containing the device.

    Step 2. Right-click the device and select Disable.


    Step 1. Right-click the device and select Properties.

    Step 2. On the General tab, look for the Device Usage display at the bottom of the window. Click the menu and select Do Not Use This Device (disable).   If you prefer to solve the problem with the device, click the Troubleshoot button.

Depending on the device, you might need to physically remove it from the system to resolve…

A+: Options for solving failing system devices

When you have a malfunctioning device, you have several options for resolving the problem:

    • Look up the Device Manager code to determine the problem and its solution. (These are just a few examples of the codes you might see in Device Manager. For a complete list, see .)

Code 1: Not configured properly, so update the driver.
Code 3: Driver could be corrupted, so uninstall-reinstall the driver.
Code 3: Your system might be running low on memory or other resources, so close some open apps and/or install more RAM.
Code 10: Device cannot start, so update the driver, and visit Microsoft KnowledgeBase article 943104 for more information.
Code 12: Device can't find adequate free resources to use; you must disable another device to use it, so use the Device Manager Troubleshooting Wizard to find the coflict, and disable or reconfigure the conflicting device, else you must disable the device.

    • Click the Troubleshoot button (if any) shown on the dev…

A+: Troubleshooting with Device Manager

If your computer has devices that are malfunctioning in a way that Device Manager can detect, or has devices that are disabled, they will be displayed as soon as you open Device Manager. If the Ports (COM and LPT) category displays a malfunctioning port, COM 2, displays an exclamation mark (!) in a yellow circle. The parallel printer port, LPT1, if disabled, shows a red X. If the malfunctioning or disabled device is an I/O port, such as a serial, parallel, or USB port, any device attached to that port cannot work until the device is working properly. Not every problem with a device shows up in Device Manager, but most problems with resource conflicts or drivers will be displayed there.To troubleshoot problems with a device in Device Manager, open its Properties sheet by double-clicking the device. Use the General tab to display the device’s status and to troubleshoot a disabled or malfunctioning device.  If the device’s General Properties sheet lacks a solution button, look up t…