Networking All-in-One For Dummies®, 7th Edition
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Library of Congress Control Number: 2018934082
ISBN 978-1-119-47160-8 (pbk); ISBN 978-1-119-47162-2 (ebk); ISBN 978-1-119-47159-2 (ebk)
Welcome to the seventh edition of Networking All-in-One For Dummies, the one networking book that’s designed to replace an entire shelf full of the dull and tedious networking books you’d otherwise have to buy. This book contains all the basic and not-so-basic information you need to know to get a network up and running and to stay on top of the network as it grows, develops problems, and encounters trouble.
If you’re just getting started as a network administrator, this book is ideal. As a network administrator, you have to know about a lot of different topics: installing and configuring network hardware and software, planning a network, working with TCP/IP, securing your network, working with mobile devices, virtualizing your servers, backing up your data, managing cloud services, and many others.
You can, and probably eventually will, buy separate books on each of these topics. It won’t take long before your bookshelf is bulging with 10,000 or more pages of detailed information about every imaginable nuance of networking. But before you’re ready to tackle each of those topics in depth, you need to get a bird’s-eye picture. This book is the ideal way to do that.
And if you already own 10,000 pages or more of network information, you may be overwhelmed by the amount of detail and wonder, “Do I really need to read 1,000 pages about BIND to set up a simple DNS server?” or “Do I really need a 6-pound book to show me how to install Linux?” Truth is, most 1,000-page networking books have about 100 or so pages of really useful information — the kind you use every day — and about 900 pages of excruciating details that apply mostly to networks at places like NASA and the CIA.
The basic idea of this book is that I’ve tried to wring out the 100 or so most useful pages of information on nine different networking topics: network basics, building a network, network administration and security, troubleshooting and disaster planning, working with TCP/IP, home networking, wireless networking, Windows server operating systems, and Linux.
So whether you’ve just been put in charge of your first network or you’re a seasoned pro, you’ve found the right book.
Networking All-in-One For Dummies, 7th Edition, is intended to be a reference for all the great things (and maybe a few not-so-great things) that you may need to know when you’re setting up and managing a network. You can, of course, buy a huge 1,000-page book on each of the networking topics covered in this book. But then, who would you get to carry them home from the bookstore for you? And where would you find the shelf space to store them? In this book, you get the information you need all conveniently packaged for you in between one set of covers.
This book doesn’t pretend to be a comprehensive reference for every detail of these topics. Instead, this book shows you how to get up and running fast so that you have more time to do the things you really want to do. Designed using the easy-to-follow For Dummies format, this book helps you get the information you need without laboring to find it.
Networking All-in-One For Dummies, 7th Edition, is a big book made up of several smaller books — minibooks, if you will. Each of these minibooks covers the basics of one key element of network management, such as setting up network hardware, installing a network operating system, or troubleshooting network problems. Whenever one big thing is made up of several smaller things, confusion is always a possibility. That’s why Networking All-in-One For Dummies, 7th Edition, is designed to have multiple access points (I hear an acronym coming on — MAP!) to help you find what you want. At the beginning of the book is a detailed table of contents that covers the entire book. Then each minibook begins with a minitable of contents that shows you at a glance what chapters are included in that minibook. Useful running heads appear at the top of each page to point out the topic discussed on that page. And handy thumb tabs run down the side of the pages to help you find each minibook quickly. Finally, a comprehensive index lets you find information anywhere in the entire book.
This isn’t the kind of book you pick up and read from start to finish, as though it were a cheap novel. (If I ever see you reading it at the beach, I’ll kick sand in your face.) This book is more like a reference — the kind of book you can pick up, turn to just about any page, and start reading. You don’t have to memorize anything in this book. It’s a need-to-know book: You pick it up when you need to know something. Need to know how to set up a DHCP server in Windows? Pick up the book. Need to know how to create a user account in Linux? Pick up the book. Otherwise, put it down, and get on with your life.
Within this book, you may note that some web addresses break across two lines of text. If you’re reading this book in print and want to visit one of these web pages, simply key in the web address exactly as it’s noted in the text, pretending as though the line break doesn’t exist. If you’re reading this as an e-book, you’ve got it easy — just click the web address to be taken directly to the web page.
As I was writing this book, I made a few assumptions about you, the reader:
Like any For Dummies book, this book is chock-full of helpful icons that draw your attention to items of particular importance. You find the following icons throughout this book:
Hold it — technical stuff is just around the corner. Read on only if you have your pocket protector.
Pay special attention to this icon; it lets you know that some particularly useful tidbit is at hand.
Did I tell you about the memory course I took?
Danger, Will Robinson! This icon highlights information that may help you avert disaster.
In addition to what you’re reading right now, this product also comes with a free access-anywhere Cheat Sheet that includes tables where you can record key network and Internet connection information, the RJ-45 pin connections, private IP address ranges, and useful websites for networking information. To get this Cheat Sheet, simply go to www.dummies.com and type Networking All-in-One For Dummies Cheat Sheet in the Search box.
Yes, you can get there from here. With this book in hand, you’re ready to plow right through the rugged networking terrain. Browse the table of contents, and decide where you want to start. Be bold! Be courageous! Be adventurous! And above all, have fun!
Book 1
Chapter 1
IN THIS CHAPTER
Getting a handle on networks
Considering why networking is useful (and is everywhere)
Telling the difference between servers and clients
Assessing how networks change computing life
Examining network topology
Identifying (and offering sympathy to) the network administrator
Computer networks get a bad rap in the movies. In the 1980s, the Terminator movies featured Skynet, a computer network that becomes self-aware (a computer network of the future), takes over the planet, builds deadly terminator robots, and sends them back through time to kill everyone unfortunate enough to have the name Sarah Connor. In the Matrix movies, a vast and powerful computer network enslaves humans and keeps them trapped in a simulation of the real world. And in the 2015 blockbuster Spectre, James Bond goes rogue (again) to prevent the Evil Genius Ernst Blofeld from taking over the world (again) by linking the computer systems of all the world’s intelligence agencies together to form a single all-powerful evil network that spies on everybody.
Fear not. These bad networks exist only in the dreams of science-fiction writers. Real-world networks are much more calm and predictable. Although sophisticated networks do seem to know a lot about you, they don’t think for themselves and they don’t evolve into self-awareness. And although they can gather a sometimes disturbing amount of information about you, they aren’t trying to kill you, even if your name is Sarah Connor.
Now that you’re over your fear of networks, you’re ready to breeze through this chapter. It’s a gentle, even superficial, introduction to computer networks, with a slant toward the concepts that can help you use a computer that’s attached to a network. This chapter goes easy on the details; the detailed and boring stuff comes later.
A network is nothing more than two or more computers connected by a cable or by a wireless radio connection so that they can exchange information.
Of course, computers can exchange information in ways other than networks. Most of us have used what computer nerds call the sneakernet. That’s where you copy a file to a flash drive or other portable storage device and then walk the data over to someone else’s computer. (The term sneakernet is typical of computer nerds’ feeble attempts at humor.)
The whole problem with the sneakernet is that it’s slow, and it wears a trail in your carpet. One day, some penny-pinching computer geeks discovered that connecting computers with cables was cheaper than replacing the carpet every six months. Thus, the modern computer network was born.
You can create a simple computer network by hooking together all the computers in your office with cables and using the computer’s network interface (an electronic circuit that resides inside your computer and has a special jack on the computer’s backside). Then you tweak a few simple settings in the computer’s operating system (OS) software, and — voilà! — you have a working network. That’s all there is to it.
If you don’t want to mess with cables, you can create a wireless network instead. In a wireless network, the computers use wireless network adapters that communicate via radio signals. All modern laptop computers have built-in wireless network adapters, as do most desktop computers. (If yours doesn’t, you can purchase a separate wireless network adapter that plugs into one of the computer’s USB ports.)
Figure 1-1 shows a typical network with four computers. You can see that all four computers are connected by a network cable to a central network device: the switch. You can also see that Ward’s computer has a fancy laser printer attached to it. Because of the network, June, Wally, and the Beaver can also use this laser printer.
FIGURE 1-1: A typical network.
Computer networking has its own strange vocabulary. Although you don’t have to know every esoteric networking term, it helps to be acquainted with a few of the basic buzzwords:
LAN: Networks are often called LANs, short for local area network.
LAN is the first three-letter acronym (TLA) of this book. You don’t really need to remember it or any of the many TLAs that follow. You may guess that the acronym for four-letter acronym is FLA. Wrong! A four-letter acronym is an ETLA, which stands for extended three-letter acronym. After all, it just wouldn’t be right if the acronym for four-letter acronym had only three letters.
Frankly, computer networks are a bit of a pain to set up. So, why bother? Because the benefits of having a network outweigh the difficulties of setting one up.
You don’t have to be a PhD to understand the benefits of networking. In fact, you learned everything you need to know in kindergarten: Networks are all about sharing. Specifically, networks are about sharing three things: files, resources, and programs.
Networks enable you to share information with other computers on the network. Depending on how you set up your network, you can share files with your network friends in several different ways. You can send a file from your computer directly to a friend’s computer by attaching the file to an email message and then mailing it. Or you can let your friend access your computer over the network so that your friend can retrieve the file directly from your hard drive. Yet another method is to copy the file to a disk on another computer and then tell your friend where you put the file so that your friend can retrieve it later. One way or the other, the data travels to your friend’s computer over the network cable and not on a CD or DVD or flash drive, as it would in a sneakernet.
You can set up certain computer resources — such as hard drives or printers — so that all computers on the network can access them. For example, the laser printer attached to Ward’s computer in Figure 1-1 is a shared resource, which means that anyone on the network can use it. Without the network, June, Wally, and the Beaver would have to buy their own laser printers.
Hard drives can be shared resources, too. In fact, you must set up a hard drive as a shared resource to share files with other users. Suppose that Wally wants to share a file with the Beaver, and a shared hard drive has been set up on June’s computer. All Wally has to do is copy his file to the shared hard drive in June’s computer and tell the Beaver where he put it. Then, when the Beaver gets around to it, he can copy the file from June’s computer to his own (unless, of course, that hooligan Eddie Haskell deletes the file first).
You can share other resources, too, such as an Internet connection. In fact, sharing an Internet connection is one of the main reasons why many networks are created.
Instead of keeping separate copies of programs on each person’s computer, put programs on a drive that everyone shares. For example, if ten computer users all use a particular program, you can purchase and install ten copies of the program, one for each computer. Or you can purchase a ten-user license for the program and then install just one copy of the program on a shared drive. Each of the ten users can then access the program from the shared hard drive.
In most cases, however, running a shared copy of a program over the network is unacceptably slow. A more common way of using a network to share programs is to copy the program’s installation disks or CDs to a shared network drive. Then you can use that copy to install a separate copy of the program on each user’s local hard drive. For example, Microsoft Office enables you to do this if you purchase a license from Microsoft for each computer on which you install Office.
The advantage of installing Office from a shared network drive is that you don’t have to lug around the installation disks or CDs to each user’s computer. And the system administrator can customize the network installation so that the software is installed the same way on each user’s computer. (However, these benefits are significant only for larger networks. If your network has fewer than about ten computers, you’re probably better off installing the program separately on each computer directly from the installation disks or CDs.)
Remember that purchasing a single-user copy of a program and then putting it on a shared network drive — so that everyone on the network can access it — is illegal. If five people use the program, you need to either purchase five copies of the program or purchase a network license that specifically allows five or more users.
That being said, many software manufacturers sell their software with a concurrent usage license, which means that you can install the software on as many computers as you want, but only a certain number of people can use the software at any given time. Usually, special licensing software that runs on one of the network’s server computers keeps track of how many people are currently using the software. This type of license is frequently used with more specialized (and expensive) software, such as accounting systems or computer drafting systems.
Another benefit of networking is that networks enable computer users to communicate with one another over the network. The most obvious way networks allow computer users to communicate is by passing messages back and forth, using email or instant-messaging programs. Networks also offer other ways to communicate: For example, you can hold online meetings over the network. Network users who have inexpensive video cameras (webcams) attached to their computers can have videoconferences. You can even play a friendly game of Hearts over a network — during your lunch break, of course.
The network computer that contains the hard drives, printers, and other resources that are shared with other network computers is a server. This term comes up repeatedly, so you have to remember it. Write it on the back of your left hand.
Any computer that’s not a server is a client. You have to remember this term, too. Write it on the back of your right hand.
Only two kinds of computers are on a network: servers and clients. Look at your left hand and then look at your right hand. Don’t wash your hands until you memorize these terms.
The distinction between servers and clients in a network has parallels in sociology — in effect, a sort of class distinction between the “haves” and “have-nots” of computer resources:
In some networks, a server computer is a server computer and nothing else. It’s dedicated to the sole task of providing shared resources, such as hard drives and printers, to be accessed by the network client computers. This type of server is a dedicated server because it can perform no other task than network services.
Some smaller networks take an alternative approach by enabling any computer on the network to function as both a client and a server. Thus, any computer can share its printers and hard drives with other computers on the network. And while a computer is working as a server, you can still use that same computer for other functions, such as word processing. This type of network is a peer-to-peer network because all the computers are thought of as peers, or equals.
Here are some points to ponder concerning the differences between dedicated server networks and peer-to-peer networks while you’re walking the dog tomorrow morning:
The network server features that are built into desktop versions of Windows (such as Windows 7 and 8) aren’t particularly efficient because these versions of Windows weren’t designed primarily to be network servers.
If you dedicate a computer to the task of being a full-time server, use a special server operating system rather than the standard Windows desktop operating system. A server operating system is specially designed to handle networking functions efficiently.
Besides being dedicated, your servers should also be sincere.
To use a network, you don’t really have to know much about how it works. Still, you may feel a little bit better about using the network if you realize that it doesn’t work by voodoo. A network may seem like magic, but it isn’t. The following list describes the inner workings of a typical network:
Network cable: The network cable physically connects the computers. It plugs into the network interface card (NIC) on the back of your computer.
The type of network cable most commonly used is twisted-pair cable, so named because it consists of several pairs of wires twisted together in a certain way. Twisted-pair cable superficially resembles telephone cable. However, appearances can be deceiving. Most phone systems are wired using a lower grade of cable that doesn’t work for networks.
For the complete lowdown on networking cables, see Chapter 2 of this minibook.
Network cable isn’t necessary when wireless networking is used. For more information about wireless networking, see Chapter 2 of this minibook.
Network switch: Networks built with twisted-pair cabling require one or more switches. A switch is a box with a bunch of cable connectors. Each computer on the network is connected by cable to the switch. The switch, in turn, connects all the computers to each other.
In the early days of twisted-pair networking, devices known as hubs were used rather than switches. The term hub is sometimes used to refer to switches, but true hubs went out of style sometime around the turn of the century.
I explain much more about switches and hubs in Chapter 2 of this minibook.
Network router: A router is used to connect two networks. Typically, a router is used to connect your network to the Internet. Figure 1-2 shows what the Cleaver family network would look like if they added a router to connect to the Internet. As you can see, the router is connected to the switch and also to the Internet. As a result, any computer that’s connected to the switch can also reach the Internet via the router.
In networks with just a few computers, the network switch and router are often combined into a single device. By combining a router and a switch in a single box, you can easily connect several computers to the Internet and to each other.
Wireless networks: In a wireless network, most cables and switches are moot. Radio transmitters and receivers take the place of cables.
The main advantage of wireless networking is its flexibility: No cables to run through walls or ceilings, and client computers can be located anywhere within range of the network broadcast.
There are trade-offs, though. For example, wireless networks are inherently less secure than a cabled network because anyone within range can intercept the radio signals. In addition, cabled networks are inherently faster and more stable than wireless networks.
Figure 1-3 shows how the Cleaver’s network might look if they used a single device that combines a wireless router, which also includes a built-in switch. In this example, Ward’s printer and computer are connected by wires because they’re in the same room as the router. June’s, Wally’s, and the Beave’s computers are connected wirelessly, so no cables are required.
FIGURE 1-2: Connecting to the Internet via a router.
FIGURE 1-3: Using a wireless router/switch combo.
Networks come in all sizes and shapes. In fact, networks are commonly based on the geographical size they cover, as described in the following list:
Local area networks (LANs): In this type of network, computers are relatively close together, such as within the same office or building.
Don’t let the descriptor “local” fool you. A LAN doesn’t imply that a network is small. A LAN can contain hundreds or even thousands of computers. What makes a network a LAN is that all its connected computers are located within close proximity. Usually a LAN is contained within a single building, but a LAN can extend to several buildings on a campus, provided that the buildings are close to each other (typically within 300 feet of each other, although greater distances are possible with special equipment).
Wide area networks (WANs): These networks span a large geographic territory, such as an entire city or a region or even a country. WANs are typically used to connect two or more LANs that are relatively far apart. For example, a WAN may connect an office in San Francisco with an office in New York.
The geographic distance, not the number of computers involved, makes a network a WAN. If an office in San Francisco and an office in New York each has only one computer, the WAN will have a grand sum of two computers — but will span more than 3,000 miles.