Line-of-Sight Wireless Internet Service

 

A popular choice for Internet access in rural areas, this type of Internet access uses small micro-wave antennas that receive signals from and send signals to relay towers connected to the ISP. Typical speeds range between 256Kbps and 6Mbps download (slower for upload).

 

WiMAX

 

A standard for wireless broadband Internet access advocated by the World Wide Interoperability for Microwave Access, WiMAX has a range of about 50 kilometers, making it suitable for a Metropolitan Area Network. WiMAX devices are available as adapters and as gateways.

 

 

Network Types

 

A network is a group of devices that share services. The following are the types of networks:

 

PAN (personal-area network) —Devices a few feet from each other, such as wirelessphones, mice, keyboards, and printers, can exchange information using Bluetooth.

 

LAN (local-area network) —Devices are close by (within a building, campus, or house).Wired or wireless Ethernet is used to connect devices.

 

MAN (metropolitan-area network) —Network that connects two or more locations in thesame city to each other.

 

WAN (wide-area network) —Covers a wide geographic area. WANs connect LANs to eachother.

58 CompTIA A+ Quick Reference

 

Network Topologies

 

You need to understand five different network topologies for the A+ Certification exams:

 

Mesh —All computers on the network are connected directly to each other. Typical exam-ple: Wi-Fi ad hoc network.

 

Ring —All computers pass information from computer to computer in either a physical ringlayout (typical example: FDDI network) or a logical ring layout (typical example: Token Ring).

 

Bus —All computers share a common cable. Typical examples: 10BASE2 (ThinnetEthernet) or 10BASE5 (Thicknet Ethernet).

 

Star —All computers connect to a central point (hub, switch, or access point). Typicalexamples: Wired Ethernet (10/100/1000BASE-T), wireless Ethernet running in infrastruc-ture mode.

 

Hybrid —Combination of any two or more of the above networks. For example, a mesh net-work connecting via a bridge to a star network. The combination is a hybrid network.

 

Network Devices

 

You need to know the names of the following devices as well as their functions and features for the CompTIA A+ Certification exams:

 

Hubs —A hub looks like a switch, but it is not as sophisticated. It only provides ingress, andit subdivides the overall bandwidth of the network among connected devices. For this rea-son, hubs are obsolete. A repeater retimes and regenerates signals that travel great distances. A host is any device on a network. Usually, the name host implies a PC, but it could be a printer, access point, or another networked device.

 

Switches —Switches connect to a router and provide both ingress to the network (manyports) and make forwarding decisions based on the location of the sending and receiving hosts. Switches use MAC addresses to make these decisions. They only forward packets to the intended host, which reduces overall network traffic. Most wireless routers also include a Fast Ethernet or Gigabit Ethernet switch.

 

Routers —Routers connect networks to each other. They control the addressing scheme forattached networks and route data packets to other networks. IP addressing is used by Layer 3 devices, such as routers, to identify computers on networks. A router can work with wired networks, wireless networks, or both.

 

Access points —Access points connect wireless Ethernet (Wi-Fi) clients to each other. Awireless router includes access point capabilities.

 

Bridge —A device that connects two local area networks together or separates them intosections. Bridging features are also built in to Windows.

Chapter 2: Networking 59

 

Modem —Short form of modulate-demodulate. Properly speaking, a modem is a device thatchanges computer signals into telephone signals and back again. However, Internet access devices for cable, DSL, and satellite are also referred to as modems.

 

NAS —Network-attached storage, which refers to a drive or array that has its own IPaddress. NAS devices are available for all sizes of networks, including SOHO networks.

 

Firewall —A device or program that blocks unwanted access via the network or Internet.The term firewall by itself usually refers to a hardware firewall; a software firewall is often referred to as a firewall program.

 

VoIP phone —A telephone that uses voice over IP protocols; in essence, a telephone thatuses an Internet connection rather than the traditional telephone network.

 

Internet appliance —A device that allows Internet access.

 

Using Networking Tools

 

The following tools are used to build and test a network. Make sure you know the names and func-tions of each of these tools for the CompTIA A+ Certification exams:

 

Wire or cable cutter —Use this to make a clean cut off the end of a network cable.

 

Wire stripper —Use this tool to remove the outer jacket from a network cable so the wirepairs can be exposed.

 

Punchdown tool —Use this tool to punch individual wires down into the 110 IDC clips ofan RJ-45 jack and the patch panel. This “punching down” of the wires is the actual termina-tion.

 

Crimper —Use this tool to crimp an RJ-45 connector after you insert the wire pairs into theconnector when building a patch cable or replacing a defective RJ-45 connector.

 

Loopback plug —Connect this to the RJ-45 port on a network card or port cluster to simu-late a network connection for testing.

 

Multimeter —Set it to continuity mode and use it to check the connections at both ends of anetwork cable for continuity.

 

Cable tester —A device that plugs into a port on a patch panel with a corresponding termi-nator on the other end of the cable. This device tests all wire pairs in the cable.

 

Toner probe (also known as tone and probe) —A type of cable tester that includes a tonedevice, which connects to one end of the network cable and when turned on, sends a tone along the length of the cable; and a probing device, also known as an inductive amplifier, that can pickup the tone anywhere along the cable length and at the termination point. Unlike a true cable tester, it tests only one wire pair.

 

 

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Chapter 3

 

 

Laptops

 

Laptops is one of nine domains in the 2012 CompTIA A+ exams. Laptops accounts for 11% of the 220-801 exam. This domain focuses on the unique features of laptop hardware.