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Head First Networking

Cover of Head First Networking by Al Anderson... Published by O'Reilly Media, Inc.
  1. Dedication
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  5. Authors of Head First Networking
  6. How to Use this Book: Intro
    1. Who is this book for?
      1. Who should probably back away from this book?
    2. We know what you’re thinking
    3. We know what your brain is thinking
    4. Metacognition: thinking about thinking
    5. Here’s what WE did:
    6. Here’s what YOU can do to bend your brain into submission
    7. Read Me
    8. The technical review team
    9. Acknowledgments
    10. Safari<sup xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:pls="http://www.w3.org/2005/01/pronunciation-lexicon" xmlns:ssml="http://www.w3.org/2001/10/synthesis" xmlns:svg="http://www.w3.org/2000/svg">&#174;</sup> Books Online Books Online
  7. 1. Fixing Physical Networks: Walking on Wires
    1. Coconut Airways has a network problem
      1. The booking system network cable is busted
    2. How do we fix the cable?
      1. But how do we do this?
    3. Introducing the CAT-5 cable
    4. The CAT-5 cable dissected
      1. So why are the pairs twisted?
    5. So what’s with all the colors?
    6. Let’s fix the broken CAT-5 cable
    7. A closer look at the RJ-45 connector
      1. So which wire goes where?
    8. So what are the physical steps?
    9. You fixed the CAT-5 cable
    10. Coconut Airways has more than one network
    11. Introducing the coaxial cable
    12. Coaxial networks are bus networks
    13. So can we fix the cable?
    14. The network’s still not working
    15. So what goes on inside a coaxial cable?
      1. But what if there’s a break in the conductor?
    16. What about connectors and terminators?
    17. Use toner-tracer sets to listen to electrons
    18. No sound means no electrons
      1. So how do we find the continuity break?
    19. You’ve fixed the coaxial cable
    20. Introducing fiber-optic cables
      1. Fiber-optics have connectors too
    21. The Coconut Airways cable’s over-bent
      1. So what’s a fusion splicer?
    22. How to fix fiber-optics with a fusion splicer
    23. A fiber-optic connector needs fitting too
    24. We’re nearly ready to fix the connector
    25. There are two types of fiber
      1. Single mode fiber
      2. Multimode fiber
    26. Which mode fiber should you use?
    27. Let’s fit the connector on the fiber-optic
      1. So which technique should we use?
    28. Coconut Airways is sky high
  8. 2. Planning Network Layouts: Networking in the Dark
    1. Ghost Watch needs your help!
    2. Every good network needs a good plan
    3. So how does the device list help us plan a network?
    4. How to plan a network layout
    5. Let’s plan the cabling with a floorplan
    6. Ready to plot some network cables?
    7. So where have we got to?
    8. We need to decide on the cable management hardware
    9. Uh oh! The cabling is a mess
    10. Ghost Watch needs cable management hardware
    11. Things that go bump...
    12. You’ve really cleaned up that noise and straightened out <span xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:pls="http://www.w3.org/2005/01/pronunciation-lexicon" xmlns:ssml="http://www.w3.org/2001/10/synthesis" xmlns:svg="http://www.w3.org/2000/svg" class="underline">MOST</span> of the cables! of the cables!
      1. What’s in the closet?
    13. Let’s start by labeling the cables
    14. But there are still lots of cables
      1. But what else can we do?
    15. So what’s a patch panel?
    16. Behind the scenes of a patch panel
    17. The wires go into a punch down block
    18. Roll the cameras!
  9. 3. Tools and Troubleshooting: Into the Wire
    1. Mighty Gumball won the Super Bowl contract
    2. A toner and tracer can check for a signal...
    3. ... but can’t check for signal quality
    4. Introducing the multimeter
      1. Use a multimeter to measure resistance
    5. So what’s resistance?
      1. When resistance is low
      2. When resistance is high
    6. So how well did the multimeter do?
    7. An oscilloscope shows voltage changes
    8. Voltage is really electrical pressure
      1. So how does this help us troubleshoot problems?
    9. Where does noise on network cables come from?
    10. So how well did the oscilloscope perform for Mighty Gumball?
    11. A logical analyzer uses voltage too
    12. When is a logical analyzer useful?
    13. So which tool is best?
    14. The Mighty Gumball bonus went to Jill
    15. A LAN analyzer combines the functions of all the other tools
    16. A LAN analyzer understands the network traffic in the signal
    17. So which tool is best?
    18. The Mighty Gumball problems are fixed!
  10. 4. Packet Analysis: You’ve Been Framed
    1. What’s the secret message?
      1. So how do we extract a message from a signal?
    2. Network cards handle encoding
      1. So how does the NIC encode the data?
    3. To get the message, reverse the encoding
      1. So how do we decode the signal?
    4. The Ethernet standard tells hardware how to encode the data
    5. A quick guide to binary
      1. So how do we convert a binary to decimal?
    6. Computers read numbers, humans read letters
      1. But isn’t there an easier way?
    7. Hexadecimal to the rescue
      1. So how do we convert a hexadecimal to decimal?
    8. We can convert to ASCII using hex
    9. Back at the spy agency...
    10. Protocols define the structure of a message
    11. Network frames have lots of layers
    12. Your friendly packet field guide
      1. UDP Packet - Protocol Type 17
      2. ICMP Packet - Protocol Type 1
      3. TCP Packet - Protocol Type 6
    13. So can we decode the secret message?
    14. We’ve got all the right packets... but not necessarily in the right order
    15. The packet tells you the correct order
  11. 5. Network Devices and Traffic: How Smart is Your Network?
    1. You’ve decoded the secret message...
      1. ...but how do we know who sent it?
    2. The packet information tells us where the packet came from
    3. So who’s the mole?
    4. There’s more to networks than computers
    5. Hubs don’t change the MAC address
      1. So which device sent the packet to the hub?
    6. A hub sends signals, and sends them <span xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:pls="http://www.w3.org/2005/01/pronunciation-lexicon" xmlns:ssml="http://www.w3.org/2001/10/synthesis" xmlns:svg="http://www.w3.org/2000/svg" class="underline">everywhere</span>
      1. Hubs think in terms of electricity
    7. So what passed the signal to the hub?
    8. A switch sends frames, and only sends them where they need to go
      1. Switches think in terms of frames
    9. Switches store MAC addresses in a lookup table to keep the frames flowing smoothly
    10. The switch has the information...
    11. We can use software to monitor packets
    12. Let’s hook Wireshark up to the switch
    13. Wireshark gives us traffic information
    14. Routers have MAC addresses too
    15. We’re closing in!
    16. You’ve found the mole!
  12. 6. Connecting Networks with Routers: Bringing Things Together
    1. Networking <span xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:pls="http://www.w3.org/2005/01/pronunciation-lexicon" xmlns:ssml="http://www.w3.org/2001/10/synthesis" xmlns:svg="http://www.w3.org/2000/svg" class="strikethrough">Walking</span> on the moon on the moon
    2. We need to connect two networks together
    3. The light’s on, but nobody’s home
      1. What do you think the flashing LEDs have to do with traffic on the network?
    4. Let’s see what traffic is on our network!
    5. MAC address versus IP address
    6. IP addresses give our networks a sense of location, and network nodes a sense of belonging to that location
    7. We retrieve IP addresses using the MAC address and the Address Resolution Protocol (ARP)
    8. So what’s the problem with the Moonbase?
    9. How do we get network traffic to move between networks?
    10. How the router moves data across networks
    11. Back to the Moonbase problem
    12. The secret of IP numbers is...
    13. Routers connect networks by doing the math...
    14. Back at the Moonbase...
    15. Are you ready to program the router?
    16. You just created this router config file!
    17. Let the router tell us what’s wrong...
  13. 7. Routing Protocols: It’s a Matter of Protocol
    1. Houston, we have a problem...
    2. Routing tables tell routers where to send packets
      1. We can see routes in the table using the show command
    3. Each line represents a different route
    4. So how do we enter routes?
    5. Routes help routers figure out where to send network traffic
    6. So are the moonbases now connected?
    7. Back on the moon...
      1. Moonbase 1 still has problems
    8. So how do we troubleshoot bad routes?
      1. We can start with the ping command
      2. So how does the ping command work?
    9. The traceroute command is useful too
    10. So what’s the problem with the network connection?
    11. The network address changes keep on coming...
    12. Use RIP to get routes to update themselves
      1. So what does this mean for Moonbase 1?
    13. So how do we set up RIP?
    14. But there’s still a problem...
    15. There are too many hops
    16. The routing protocol zoo
    17. So how do we setup EIGRP?
    18. We have lift off!
  14. 8. The Domain Name System: Names to Numbers
    1. The Head First Health Club needs a website
    2. Hello, my domain name is...
      1. So how do we get a domain name?
    3. Let’s go buy a domain name
    4. Uh-oh! We’re in trouble
      1. And she’s not the only one
    5. Introducing the DNS
    6. The DNS relies on name servers
    7. How the DNS sees your domain
    8. So how does this affect the Health Club?
    9. First install a DNS name server...
    10. ...then configure the name server
    11. The anatomy of a DNS zone file
    12. Here’s what the DNS zone file tells us about the Health Club servers
    13. The Health Club can’t send emails
    14. So what’s the problem?
    15. Email servers use RDNS to fight SPAM
    16. Check your sources with reverse DNS
    17. The dig command can do a reverse DNS lookup
    18. Your name server has another important zone file...
    19. The emails are working!
  15. 9. Monitoring and Troubleshooting: Listen to Your Network’s Troubles
    1. Pajama Death are back on tour
      1. So here’s your challenge...
    2. So where would you start troubleshooting a misfiring network?
    3. Start troubleshooting your network problems by checking in with your network devices
    4. Troubleshoot network connectivity with the ping command
      1. If you can ping, you get timings
      2. But what if you can’t ping?
    5. If the ping fails, check the cables
    6. Get started with the show interface command
      1. The interface’s network statistics are a gold mine of troubleshooting information
    7. The ticket network’s still not fixed
    8. SNMP to the rescue!
    9. SNMP is a network admininistrator’s communication tool
    10. How to configure SNMP on a Cisco device
    11. One hour to go...
    12. Get devices to send you their problems
    13. How to configure syslogd on a Cisco device
    14. How do you tell what’s in the logs?
      1. syslogd lets you fix problems before they’re problems
    15. Too much information can be just as bad as not enough
      1. What you need is <span xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:m="http://www.w3.org/1998/Math/MathML" xmlns:pls="http://www.w3.org/2005/01/pronunciation-lexicon" xmlns:ssml="http://www.w3.org/2001/10/synthesis" xmlns:svg="http://www.w3.org/2000/svg" class="underline">relevant</span> information information
    16. How do you know which events are important?
    17. Pajama Death’s a sell-out!
  16. 10. Wireless Networking: Working Without Wires
    1. Your new gig at Starbuzz Coffee
      1. Starbuzz Coffee needs a wireless hotspot
    2. Wireless access points create networks using radio waves
    3. Let’s fit the wireless access point
    4. What about the network configuration?
    5. So what’s DHCP?
      1. DHCP allocates IP addresses
    6. First make sure the client has DHCP turned on...
    7. Second, make the wireless access point a DHCP server...
    8. ...and then specify an acceptable range of IP addresses
    9. So has setting up DHCP solved the problem?
    10. This time it’s personal
    11. We’ve run out of IP addresses
    12. NAT works by reallocating IP addresses
    13. So how do we configure NAT?
    14. So has this fixed the problem?
    15. There’s more than one wireless protocol
      1. Most newer access point support multiple protocols
      2. So is the Starbuzz wireless access point sorted?
    16. The central Starbuzz server needs to access the cash register
    17. Port mapping to the rescue!
      1. So port mapping is a bit like NAT in reverse
    18. Let’s set up port mapping on the Starbuzz access point
    19. The wireless access point is a success!
  17. 11. Network Security: Get Defensive
    1. The bad guys are everywhere
      1. The evil impersonator
      2. The evil attacker
    2. And it’s not just the NETWORK that gets hurt...
      1. The evil eavesdropper
    3. The big four in network security
    4. Defend your network against MAC address spoofing
    5. So how do we defend against MAC address spoofing?
    6. Defend your network against ARP poisoning attacks
    7. So what can we do about ARP poisoning attacks?
    8. It’s all about the access, baby!
      1. If an attacker can get past your router, then he’s on your network!
    9. Set up your router’s Access Control Lists to keep attackers out
    10. So how do we configure the Access Control List?
    11. Firewalls filter packets between networks
    12. Packet-filtering rules!
    13. Master the static packet filter
    14. Get smart with stateful packet-filters
    15. Humans are the weakest link in your security chain
    16. So how do social engineers operate?
    17. Smash social engineering with a clear and concise security policy
    18. You’ve hardened your network
  18. 12. Designing Networks: You Gotta Have a Plan!
    1. Now you have to plan a network from scratch!
    2. You have to know what the needs are before you can plan
    3. So you’ve developed your questions, now what?
    4. Look at your action plan
    5. So you have a physical layout, what’s next?
    6. Blueprints show everything in a building’s design
    7. You may have to modify your network design based on what you see in the blueprints!
    8. So you’ve got your physical network layout, what’s next?
      1. You have got several options to segment this into two networks
    9. Finally, you need an implementation plan
    10. Leaving town...
    11. It’s been great having you here in Networkville!
  19. A. Leftovers: The Top Ten Things (we didn’t cover)
    1. #1 Network topologies
      1. Star topology
      2. Bus topology
      3. Token Ring topology
    2. #2 Installing Wireshark
      1. Windows Install
      2. Mac OS X Install
      3. Linux Install (Ubuntu)
    3. #3 How to get to the console or terminal
      1. Windows
      2. Linux
      3. Mac OS X
    4. #4 The TCP Stack
    5. #5 VLANS
    6. #6 Cisco IOS Simulators
    7. #7 BGP
    8. #8 VPN
    9. #9 Intrusion Detection Systems
    10. #10 Cisco Certification
  20. B. Ascii Tables: Looking Things Up
    1. ASCII tables 0-31
    2. ASCII code tables 32-63
    3. ASCII code tables 64-95
    4. ASCII code tables 96-127
  21. C. Installing Bind: Getting a Server to talk DNS
    1. #1 Installing BIND on Windows (XP, 2000, Vista)
    2. #2 Installing BIND Mac OS X Server
    3. #3 Installing BIND Mac OS X Client & Linux
  22. Index
  23. About the Authors
  24. Special Upgrade Offer
  25. Copyright
O'Reilly logo

How to Use this Book: Intro

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In this section we answer the burning question: “So why DID they put that in a networking book?”

Who is this book for?

If you can answer “yes” to all of these:

  1. Do you need to learn networking for a job, for a class (like CCNA), or just because you think it’s about time you learned the difference between a switch and a router?

  2. Do you want to learn, understand, and remember how to run an industrial-strength packet sniffer, set up a Domain Name System server, build firewall packet filters, and configure routing protocols like EIGRP?

  3. Do you prefer stimulating dinner party conversation to dry, dull, academic lectures?

this book is for you.

Who should probably back away from this book?

If you can answer “yes” to any of these:

  1. Are you completely new to computers?

  2. Are you a CCNA or CCNP looking for a reference book?

  3. Are you afraid to try something different? Would you rather have a root canal than mix stripes with plaid? Do you believe that a technical book can’t be serious if it anthropomorphizes multimeters and oscilloscopes?

this book is not for you.

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[Note from marketing: this book is for anyone with a credit card.]

We know what you’re thinking

“How can this be a serious networking book?”

“What’s with all the graphics?”

“Can I actually learn it this way?”

We know what your brain is thinking

Your brain craves novelty. It’s always searching, scanning, waiting for something unusual. It was built that way, and it helps you stay alive.

So what does your brain do with all the routine, ordinary, normal things you encounter? Everything it can to stop them from interfering with the brain’s real job—recording things that matter. It doesn’t bother saving the boring things; they never make it past the “this is obviously not important” filter.

How does your brain know what’s important? Suppose you’re out for a day hike and a tiger jumps in front of you, what happens inside your head and body?

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Neurons fire. Emotions crank up. Chemicals surge.

And that’s how your brain knows...

This must be important! Don’t forget it!

But imagine you’re at home, or in a library. It’s a safe, warm, tiger-free zone. You’re studying. Getting ready for an exam. Or trying to learn some tough technical topic your boss thinks will take a week, ten days at the most.

Just one problem. Your brain’s trying to do you a big favor. It’s trying to make sure that this obviously non-important content doesn’t clutter up scarce resources. Resources that are better spent storing the really big things. Like tigers. Like the danger of fire. Like how you should never have posted those “party” photos on your Facebook page. And there’s no simple way to tell your brain, “Hey brain, thank you very much, but no matter how dull this book is, and how little I’m registering on the emotional Richter scale right now, I really do want you to keep this stuff around.”

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Metacognition: thinking about thinking

If you really want to learn, and you want to learn more quickly and more deeply, pay attention to how you pay attention. Think about how you think. Learn how you learn.

Most of us did not take courses on metacognition or learning theory when we were growing up. We were expected to learn, but rarely taught to learn.

But we assume that if you’re holding this book, you really want to learn networking. And you probably don’t want to spend a lot of time. If you want to use what you read in this book, you need to remember what you read. And for that, you’ve got to understand it. To get the most from this book, or any book or learning experience, take responsibility for your brain. Your brain on this content.

The trick is to get your brain to see the new material you’re learning as Really Important. Crucial to your well-being. As important as a tiger. Otherwise, you’re in for a constant battle, with your brain doing its best to keep the new content from sticking.

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So just how DO you get your brain to treat networking like it was a hungry tiger?

There’s the slow, tedious way, or the faster, more effective way. The slow way is about sheer repetition. You obviously know that you are able to learn and remember even the dullest of topics if you keep pounding the same thing into your brain. With enough repetition, your brain says, “This doesn’t feel important to him, but he keeps looking at the same thing over and over and over, so I suppose it must be.”

The faster way is to do anything that increases brain activity, especially different types of brain activity. The things on the previous page are a big part of the solution, and they’re all things that have been proven to help your brain work in your favor. For example, studies show that putting words within the pictures they describe (as opposed to somewhere else in the page, like a caption or in the body text) causes your brain to try to makes sense of how the words and picture relate, and this causes more neurons to fire. More neurons firing = more chances for your brain to get that this is something worth paying attention to, and possibly recording.

A conversational style helps because people tend to pay more attention when they perceive that they’re in a conversation, since they’re expected to follow along and hold up their end. The amazing thing is, your brain doesn’t necessarily care that the “conversation” is between you and a book! On the other hand, if the writing style is formal and dry, your brain perceives it the same way you experience being lectured to while sitting in a roomful of passive attendees. No need to stay awake.

But pictures and conversational style are just the beginning...

Here’s what WE did:

We used pictures, because your brain is tuned for visuals, not text. As far as your brain’s concerned, a picture really is worth a thousand words. And when text and pictures work together, we embedded the text in the pictures because your brain works more effectively when the text is within the thing the text refers to, as opposed to in a caption or buried in the text somewhere.

We used redundancy, saying the same thing in different ways and with different media types, and multiple senses, to increase the chance that the content gets coded into more than one area of your brain.

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We used concepts and pictures in unexpected ways because your brain is tuned for novelty, and we used pictures and ideas with at least some emotional content, because your brain is tuned to pay attention to the biochemistry of emotions. That which causes you to feel something is more likely to be remembered, even if that feeling is nothing more than a little humor, surprise, or interest.

We used a personalized, conversational style, because your brain is tuned to pay more attention when it believes you’re in a conversation than if it thinks you’re passively listening to a presentation. Your brain does this even when you’re reading.

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We included more than 80 activities, because your brain is tuned to learn and remember more when you do things than when you read about things. And we made the exercises challenging-yet-do-able, because that’s what most people prefer.

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We used multiple learning styles, because you might prefer step-by-step procedures, while someone else wants to understand the big picture first, and someone else just wants to see an example. But regardless of your own learning preference, everyone benefits from seeing the same content represented in multiple ways.

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We include content for both sides of your brain, because the more of your brain you engage, the more likely you are to learn and remember, and the longer you can stay focused. Since working one side of the brain often means giving the other side a chance to rest, you can be more productive at learning for a longer period of time.

And we included stories and exercises that present more than one point of view, because your brain is tuned to learn more deeply when it’s forced to make evaluations and judgments.

We included challenges, with exercises, and by asking questions that don’t always have a straight answer, because your brain is tuned to learn and remember when it has to work at something. Think about it—you can’t get your body in shape just by watching people at the gym. But we did our best to make sure that when you’re working hard, it’s on the right things. That you’re not spending one extra dendrite processing a hard-to-understand example, or parsing difficult, jargon-laden, or overly terse text.

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We used people. In stories, examples, pictures, etc., because, well, because you’re a person. And your brain pays more attention to people than it does to things.

Here’s what YOU can do to bend your brain into submission

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Cut this out and stick it on your refrigerator.

So, we did our part. The rest is up to you. These tips are a starting point; listen to your brain and figure out what works for you and what doesn’t. Try new things.

  1. Slow down. The more you understand, the less you have to memorize.

    Don’t just read. Stop and think. When the book asks you a question, don’t just skip to the answer. Imagine that someone really is asking the question. The more deeply you force your brain to think, the better chance you have of learning and remembering.

  2. Do the exercises. Write your own notes.

    We put them in, but if we did them for you, that would be like having someone else do your workouts for you. And don’t just look at the exercises. Use a pencil. There’s plenty of evidence that physical activity while learning can increase the learning.

  3. Read the “There are No Dumb Questions”

    That means all of them. They’re not optional sidebars, they’re part of the core content! Don’t skip them.

  4. Make this the last thing you read before bed. Or at least the last challenging thing.

    Part of the learning (especially the transfer to long-term memory) happens after you put the book down. Your brain needs time on its own, to do more processing. If you put in something new during that processing time, some of what you just learned will be lost.

  5. Talk about it. Out loud.

    Speaking activates a different part of the brain. If you’re trying to understand something, or increase your chance of remembering it later, say it out loud. Better still, try to explain it out loud to someone else. You’ll learn more quickly, and you might uncover ideas you hadn’t known were there when you were reading about it.

  6. Drink water. Lots of it.

    Your brain works best in a nice bath of fluid. Dehydration (which can happen before you ever feel thirsty) decreases cognitive function.

  7. Listen to your brain.

    Pay attention to whether your brain is getting overloaded. If you find yourself starting to skim the surface or forget what you just read, it’s time for a break. Once you go past a certain point, you won’t learn faster by trying to shove more in, and you might even hurt the process.

  8. Feel something.

    Your brain needs to know that this matters. Get involved with the stories. Make up your own captions for the photos. Groaning over a bad joke is still better than feeling nothing at all.

  9. Get your hands dirty!

    There’s only one way to learn to network: get your hands dirty. And that’s what you’re going to do throughout this book. Networking is a skill, and the only way to get good at it is to practice. We’re going to give you a lot of practice: every chapter has exercises that pose a problem for you to solve. Don’t just skip over them—a lot of the learning happens when you solve the exercises. We included a solution to each exercise—don’t be afraid to peek at the solution if you get stuck! (It’s easy to get snagged on something small.) But try to solve the problem before you look at the solution. And definitely get it working before you move on to the next part of the book.

Read Me

This is a learning experience, not a reference book. We deliberately stripped out everything that might get in the way of learning whatever it is we’re working on at that point in the book. And the first time through, you need to begin at the beginning, because the book makes assumptions about what you’ve already seen and learned.

We begin by teaching basic concepts like cabling and physical layout, then we move on to signals and hardware, and then onto stuff like wireless networking, security, and network design.

While it’s important to create well-designed networks, before you can, you need to understand the basic components and concepts of networking. So we begin by having you physically layout simple networks and work with network cables. Then, a bit later in the book, we show you good network design practices. By then you’ll have a solid grasp of the basic information and can focus on the advanced aspects of network design.

We don’t cover every networking technology on the planet.

While we could have put every single networking technology in this book, we thought you’d prefer to have a reasonably liftable book that would teach you the networking technologies that will get you up and running. We give you the ones you need to know, the ones you’ll use 95 percent of the time. And when you’re done with this book, you’ll have the confidence to go research that hot new technology and implement on your kickass network.

We intentionally cover things differently than the other networking books out there.

Trust us. We’ve read a lot of networking books. We decided to write a book that our students could use, a practical book that didn’t start out with the OSI layer model. We like it when our students stay awake in class. We also cover stuff we couldn’t find in other books: all that structural stuff that keeps your cables neat and out of sight; how signals get encoded into binary, hex, and ascii; and how reading blueprints can help you lay out your network.

The activities are NOT optional.

The exercises and activities are not add-ons; they’re part of the core content of the book. Some of them are to help with memory, some are for understanding, and some will help you apply what you’ve learned. Don’t skip the exercises. The crossword puzzles are the only thing you don’t have to do, but they’re good for giving your brain a chance to think about the words and terms you’ve been learning in a different context.

The redundancy is intentional and important.

One distinct difference in a Head First book is that we want you to really get it. And we want you to finish the book remembering what you’ve learned. Most reference books don’t have retention and recall as a goal, but this book is about learning, so you’ll see some of the same concepts come up more than once.

The book doesn’t end here.

We love it when you can find fun and useful extra stuff on book companion sites. You’ll find extra stuff on networking at the following two urls:

http://www.headfirstlabs.com/books/hfnw/

http://www.hfnetworking.com

The Brain Power exercises don’t have answers.

For some of them, there is no right answer, and for others, part of the learning experience of the Brain Power activities is for you to decide if and when your answers are right. In some of the Brain Power exercises, you will find hints to point you in the right direction.

The technical review team

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Jonathan Moore

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Tim Olson

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Rohn Wood

Technical Reviewers:

Johnathan Moore has ten years of experience as a network technical consultant and contractor. He owns Forerunner Design, a Web design and development business located in Wenatchee Washington.

Tim Olson teaches computer engineering and physics at Salish Kootenai College and is on the science team for the NASA Mars Science Laboratory mission. He enjoys skiing and horseback riding with his family in the mountains of western Montana.

Rohn Wood lives and works in Montana trying to bring high performance computing to the old West. A full time employee of the University of Montana and half-time employee of the University of Washington, he makes his living off his UNIX chops and works remotely from his home in the Bitterroot Mountains with a view down into the valley a few miles from Travelers Rest where Lewis and Clark laid over with Corps of Discovery two hundred years ago. An 18 year user of Linux and a veteran of RS232 Gandalf Boxes, ThinNET, and Token Ring, Rohn appreciates the need for learning the hard way and RTFM.

Acknowledgments

Our editor:

Thanks to our editor, Brett McLaughlin, who dove into this project when he had a massive load of other things to do. Brett helped us by putting our ideas on trial, opening our eyes to things we didn’t see, and pushing us to produce the best book we possibly could. Brett, you are a juggernaut of production! Ryan would especially like to mention that his sessions with Brett and Al kept him going during a difficult life transition. Thanks, guys!

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The O’Reilly Team:

Thanks to Dawn Griffiths for the excellent and magical work she did to shape this book up and make it look beautiful.

Thanks to Catherine Nolan for taking a chance on two “fliers” from Montana.

Thanks to Laurie Petrycki for gambling on us and welcoming us to Boston and O’Reilly Media as if we were long-lost family.

Thanks also to the Head First folks we met in Boston, especially our brothers and sisters-in-arms: David Griffiths, Dawn Griffiths, Lynn Beighley, Cary Collett and Louise Barr. Thanks to Karen Shaner, Brittany Smith, and Caitrin McCullough.

We will never forget the day we discovered the Head First series at the bookstore. Thanks to Kathy Sierra and Bert Bates for lighting up the neurons of geeks everywhere.

Thanks to Tim O’Reilly for his vision in creating the best geek press ever!

Al’s Friends and Family:

Without Emily, my wife, I would have not been able to write this book. She took care of business while I hunkered down in the den all those countless weekends and evenings. I love you honey! Without Ella and Austin’s patience with their dad, this would have been a much harder project to accomplish. I love you guys too! Finally, my faithful dog CC, she was always with me in the den, sleeping of course.

Ryan’s Friends and Family:

Thank you to my daughter, Josefina, and my son, Vincenzo, who love books as much as I do. Thanks to my sweetie, Shonna Sims, who believed in me just when I was about to give up on this book. Thanks also to my Mom and Pops, my brother Jeff, my nieces Claire and Quinn, Dr. Tracee Jamison, Yumi Hooks, Dr. Giuseppi Onello, Curtis Cladouhos, Garret Jaros, Henrietta Goodman, and Dr. Paul Hansen (without whom I never would have gotten into technology in the first place). A huge thanks to my co-author, Al, about whom people often ask, “Is that your brother?” In many ways, he is.

A Special Thank You from Al and Ryan:

Thanks to the IT students of Salish Kootenai College, without whom we would never have been inspired to write this book in the first place.

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