A+ Chptr. 16

Clients

A client is a computer that uses the resources on a server. Depending on the network OS in use, clients and servers can be separate machines or a client can act as a server and a server can act as a client. Clients can refers to servers either by assigning drive letters to shared folders or by using a Universal Naming Convention (UNC) path name to refer to the server.

Firewall

A firewall is any hardware appliance or software application that protects a computer from unwanted intrusion. In the networking world we are more concerned with hardware-based devices that protect an entire group of computers such as a LAN. When it comes to small offices and home offices, firewall functionality is usually built into the router. In larger organizations it is a separate device. The firewall stops unwanted connections from the outside and can block basic networking attacks.

Servers

A server is a computer on the network that provides other computers (called clients or workstations) access to resources, such as disk drives,folders,printers,modems,scanner and Internet access. Because these resources can be used by different computers over the network, they are called shared resources. (Application servers run apps for clients, File servers store data and program files for clients, and mail servers store and distribute email to clients. Servers typically have more powerful hardware features, such as SCSI or SATA RAID arrays or network-attached storage for hard disk storage, larger amounts of RAM, hot-swap power supplies, and server-optimized network adapters.

Modem Technologies and Types: Add-On Card

Add-on card modems for desktop computers

Dial-Up Internet Service Providers

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

Network Devices: Bridge

Bridges can either connect two LANs together or separate them into two sections. There are wired and wireless bridges.

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 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.

Cable Internet

Cable Internet service piggybacks on the same coaxial cable that brings cable TV into a home or business. A few early cable ISPs used internet cable modems, which supported one-way traffic (The cable was used for downloads, and a conventional telephone line was used for uploads and page requests.) Virtually all cable Internet service today is two-way and is built upon the fiber-optic network used for digital cable and music services provided by most cable TV vendors. (Downlaod 2Mbps- 50Mbps, Upload 10% of Download)

Peer to Peer

Computers can share resources with each other, and machines that share resources can also be used as client workstations. Peer to Peer connections also use the UNC (or Universal Naming Convention). The peer server loads file and printer-sharing software to make printers and drives or folders available to others.

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.

Network Topologies: Peer to Peer (Mesh)

Computers in a peer to peer or mesh topology can connect directly to every other computer. This topology is used by computers with multiple adapters, Wireless Enet (Wi-Fi) when config'd for peer to peer, and bluetooth.

Network Topologies: 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.

Network Topologies: Star

Computers in a star hub connect to a central hub or switch (wired) or access point (wireless). This topology is used by 10BASE-T (10Mbps Enet), 100BASE-T (Fast Enet), and 1000BASE-T (Gigabit Enet)

Network Devices: Hub

Creates a simple shared physical plant that all computers use to send data. This device broadcasts data out to all computers. The computer that it is meant for accepts the data; the rest drop the information. B/c of this broadcasting and sharing, this device allowed only two computers to communicate with each other at any given time. (Uses the IEEE standard of 802.3)

DSL

DSL can piggyback on the same telephone line used by your telephone and fax machine, or it can be installed as a distinctly separate line. Either way, DSL requires a high-quality telephone line that can carry a digital signal. For home use, DSL is designed strictly for Internet access. But for business use, DSL can be used for additional services and can be used in site to site scenarios between organizations.

Network Devices: Network Attached Storage (NAS)

Device that contains multiple hard drives (often hot-swappable) that connect directly to the network. Data can be stored to and retrieved from these devices by way of mapped network drives, and of course exploring the network.

Modems and Dial-Up Internet Connectivity

Dial-up networking (DUN) was 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 dial-up modem, you are making a network connection

Network Devices: Switch

Each port on the switch works independently allowing more than one concurrent session. The switch sends information to specific computer that it was meant for, and that computer only; it does this by identifying the MAC address of each computer. In today's networks, the switch is king and is common in 10Mbps and 100Mbps, and 10 Gbps networks. (Uses the IEEE standard of 802.3)

Modem Technologies and Types: External

External modems plug into a serial or USB

FTP

File Transfer Protocol (FTP) is a protocol used by both web browsers and specialized FTP programs to access dedicated file transfer servers for file downloads and uploads. When you access an FTP site, the site used the prefix ftp://.

HTML

Hypertext Markup Language (HTML) is the language used by web pages. An HTML page is a specially formatted text page that uses tags (commands contained in angle brackets) to change text appearance, insert links to other pages, display pictures, incorporate scripting languages, and provide other features. Web browsers, such as Mircosoft Internet Explorer and Firefox, are used to view and interpret the contents of web pages, which have typical file extensions such as .HTM, .HTML, .ASP and others.

HTTP/HTTPS

Hypertext Transfer Protocol (HTTP) is the protocol used by web browser, such as Internet Explorer, Firefox, Chrome, to access websites and content. Normal (unsecured) sires use the prefix http:// when accessed in a web browser. Sites (HTTPS) that are secured with various encryption schemes are identified with the prefix https://.

ISDN Internet Connectivity

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 connections 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 telephone company's central switch, ISDN service is not available or a new telephone line must be run.

Fiber-Optic

Instead of using a copper connection to the home or business the way dial-up, DSL, or cable Internet do, some companies offer fiber-optic connections direct to the home. Fiber-optic cables can run at much higher data transfer rates than copper-based cables. One example where this is evident is Verizon FIOS, which can be used to bundle various services but especially offers much faster download speeds, from 3Mbps to 150 Mbps. Upload speeds are typically less as they are in most Internet Services, generally from 1Mbps to 35 Mbps

Cellular

It's also possible to connect to the Internet directly through your cellular phone or smartphone even if no Wi-Fi access point is available. This is usually done through the Global System for Mobile Communications (GSM) you might have heard of terms 2G, 3G and currently 4G These refer to the different generations (and speeds) of GSM. Most Cellular devices are equipped with 3G antenna, which can achieve a maximum theoretical DL speed of 56 Mbps,through rarely accomplished in reality due to signal strength, location, and so on. 4G has peak requirements of 100Mbps.

WAN

LANs in different cities can be connected to each other by a WAN network.

LAN

Local Area network is when two or more computers are connected together in the same office/space.

Modem Technologies and Types: Mini-PCIe Card

Many late-model notebook computers that appear to have built-in modems actually use modems that use the mini-PCIe form factor and can be removed and replaced with another unit

Modem Technologies and Types:Motherboard-integrated

Many recent desktop computers have integrated modems, as do many notebook computers

Modem

Now, let's move outside the LAN and talk about Internet and wide area network connectivity. The term modem is a conjunction of the words modulate and demodulate. It is a device that allows a computer to access the Internet by changing the digital signals of the computer to analog signals used by a typical land-based phone line. These are slow devices and are usually used only if no other Internet option is available.

Modem Technologies and Types: PC Card

PCMCIA (PC Card) modems are sometimes built in a combo design that also incorporates a 10/100 Ethernet network adapter

Satellite

Satellite Internet providers, such as HughesNet (previously known as DirecWAY and before that as DirecPC), StarBand, and WildBlue use dish antennas similar to satellite TV antennas to receive and transmit signals between geosynchronous satellites and computers. In some cases, you might be able to use a dual-purpose satellite dish to pick up both satellite Internet and satellite TV service.

SSH

Secure Shell (SSH) allows data to be exchanged between computer on a secured channel. This protocol offers a more secure replacement to FTP and Telenet. The Secure Shell server housing the data you want to access would have port 22 open. Several other protocol use SSH as a way of making a secure connection. One of these is Secure FTP (SFTP). Regular FTP can be insecure. SFTP combats this by providing file access over a reliable data stream, generated and protected by SSH.

SSL

Secure Socket Layers (SSL) is an encryption technology used b y secured (https://) websites. To access a secured website, the web browser must support the same encryption level used by the secured website (noramlly 128-bit encryption) and the same version(s) of SSL used by the website (normally SSL version 2.0 or 3.0)

Modem Technologies and Types: Mini-PCI Card

Some older-model computers that appear to have built-in modems actually use modems that use the mini-PCI form factor and can be removed and replaced with another unit.

TCP/IP

TCP/IP is short for Transport Control Protocol/Internet Protocol. It is a multi-platform protocol used for both Internet access and local area networks. Though there are other networking protocols, TCP/IP is by far the most common and is used by all major operating system including Windows 7/Vista/XP and Linux.

Telenet

Telenet enables a user to make a text-based connection to a remote computer or networking device and use it as if he were a regular user sitting in front of it, rather than simply downloading pages and files as he would with an http:// or ftp:// connection.

WiMAX

The Worldwide Interoperability for Microwave Access (WiMAX) is a wireless technology that offers high-speed connections within the 4G range, but over much larger distances than a standard Wi-Fi access point could, on average 50 KM. So, if your organization is within 50Km of an urban area, it might be able to connect its LAN to the Internet at high-speed in a completely wireless fashion. There are individual WiMAX modems for laptops and PCs and gateway devices for entire LANs. For an optimal connection, these gateways (or routers) will usually be placed on a window sill facing where the signal is coming from.

DNS

The domain name system (DNS) is the name for the network of servers on the Internet that translate domain names, such as www.informit.com, and individual host names into their matching UP addresses. If you manually configure an IP address, you typically provide the IP address, you typically provide the IP addresses of one or more DNS servers as part of the configuration.

Client/Server

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

Router

The router enables these connections with individual high-speed interconnection points. A common example would be an all-in-one device or multifunction network device that might be used in a home or small office. These devices route signals for all the computer on the LAN out to the Internet.

Internet Appliance

The term Internet appliance refers to any device that enables easy connectivity to the Internet. Historically, that was usually its only function and was often implemented in the form of handheld devices. Nowadays, some people refer to tablets such as Apple's iPad as an Internet appliance though the iPad is not limited to that singular purpose.

ISDN Hardware

To make an ISDN connection, your PC (and any other devices that share the ISDN connection) needs a device called a ISDN terminal adapter (TA). A TA resembles a conventional analog modem. Internal models plug into the same PCI, ISA, and PC Card slots used by analog modems, and eternal models use USB or serial ports. External TAs often have two or more RJ-11 ports for telephony devices an RJ-45 port for the connection to ISDN line, and a serial or USB port for connection to the computer.

TLS

Transport Layer Security (TLS) is the successor to SSL. SSL3 was somewhat of a prototype to TLS and was not fully standardized. TLS was ratified by the IETF in 1999. However, many people and companies might still refer to it as SSL.

VoIP Phones

Voice over Internet Protocol (VoIP) is a collection of technologies, devices, and protocols that allows voice communication over IP-based networks. VoIP phones are the Internet telephony devices that a person would use to make conversations. These devices connect directly to the Ethernet network and communicate on the network just like a computer. All of the words you speak are converted and encapsulated into packets that are sent across the network. It is a cheaper method of telephony, but there can be sound quality and latency issues if they are not configured properly

Network Devices: Wireless Access Point (WAP)

WAP is the wireless equivalent of the Switch, but instead of using the IEEE 802.3 standard it uses the 802.11 group of standards, which define wireless LANs (WLANs).