Chapter 8: Network Implementation

Certification Objectives. 1

Administrative and Test Accounts. 3

From the Field. 5

Passwords. 6

IP Addresses. 8

IP Configurations. 9

Name Resolution. 11

WINS. 11

DNS. 11

Relevant SOPs. 11

Cables. 13

The Network Operations Center 14

Room Conditions. 14

Minimizing Electrical Interference. 14

Computer Chassis. 14

Error Messages. 15

Network Interface Card. 16

Network Connection. 17

Serial Port 17

Parallel Port 17

Universal Serial Bus (USB) 18

SCSI 18

Interrupts. 18

Print Servers. 18

Peripherals. 18

Bridge. 19

Hub (Shared) 19

Switch. 20

Router 21

Gateway. 23

Incompatibilities with Analog Modems and a Digital Jack. 23

Uses of RJ-45 Connectors with Different Cabling. 23

Patch Cables and Length of the Cabling Segment 23

 

Certification Objectives

       Installing the Network

       Environmental Factors That Affect Computer Networks

       Common Peripheral Ports and Network Components

       Compatibility and Cabling Issues

You’ll find many questions concerning installing and maintaining computer networks located throughout the Knowledge of Networking Technology section of the Network+ exam. Knowing the different concepts behind computer networking is very important and provides a strong foundation for other sections of the exam. When you work with computer networks, you need to know the different components that make up the physical network as well as know the theoretical terms used in computer networking as a whole.

Before you can begin connecting and shaping your network, you need to understand the concepts of computer networking. You might encounter problems with the computer network or the connection between two network segments and need to troubleshoot where the network problem is. Knowing the complete picture of how networking works and the different components involved, from the cabling technologies to networking appliances, such as routers and switches, will help you understand networking so much more.

In addition to knowing the different networking areas for this exam, you need to know and understand PC fundamentals. This includes different environmental characteristics of how PCs relate, as well as basic troubleshooting techniques. When you couple knowledge of these computer technologies with “real-world” experience, you will be a force to be reckoned with in the Information Technology industry.

Installing the Network

Installing a computer network may seem like a mindless task of just connecting a few cables, but it’s really much more complicated than that. You need to know how each independent component operates, and you need to learn many different terms. You have to think about many different aspects of your computer network other than how you are going to physically connect the network cables to your PC.

When you first decide to hook up a network, you will encounter many different things that you have probably never thought about before. Well, don’t worry, because every person in the IT field has been there before. Before you can consider yourself an expert on computer networking, several important areas need your undivided attention.

First, you need to plan how to configure your network. You have a lot of choices.  You have to decide how to lay out your physical location. You have to choose between several different network topologies , and some work better than others depending on the situation. As you learned in the first chapter, each topology comes with advantages and disadvantages; you have to choose which will fit your environment the best. Choosing the best networking topology and implementing that technology correctly is what separates the good network administrators from the not-so-good.

Although the physical structure of the network is very important, you also have to provide for the administrative duties that need to be performed for your network to operate. These include setting up administrative and test accounts, passwords, IP addresses, IP configurations, connectivity requirements, and the necessary software so that once you have your network working, each client can communicate with one another. Without these ingredients, all that you end up with are a lot of very expensive computer components.

When you’ve built the physical architecture for your network, you still have a lot of work in front of you to make sure that your network can function. As the administrator, you have total control over the layout and structure of your network, as well as how each client will communicate with other clients or servers. It’s up to you to decide upon which components to throw away and which technologies to utilize to the best of your ability.

You have “administrative” control over the network, so you are in control. With the Administrator account rights for your network comes a big responsibility. You will be responsible for the security of the data, the efficiency of the network, and many other aspects that you may not have thought of yet, such as printing, sharing of files, and e-mail. These specific areas of networking are probably not what you imagined when you first thought of creating a network. However, these are all very important in the big picture of what you have before you.

Your most important duty as network administrator is to make sure that the clients on your network can communicate with one another at all times. Without this capability, your network is pretty much worthless. Besides supplying fundamental non-stop access to the network, you have to try to make sure that the people who are using the network won’t be interrupted during working hours. Sounds like an easy job, right? Well, read on and see what’s in store.

Communication on a computer network is accomplished by the use of protocols. You can choose from hundreds of different protocols, but one of the most widely adopted standards in the computer industry is the TCP/IP protocol. You may be familiar with this protocol if you have ever surfed the Internet or downloaded a file.

An easy way to think of protocols is to consider them as you would a language. For example, for computers to talk to one another, they have to be speaking the same language, or using the same protocol. A French-speaking person and an English-speaking person might be able to hear one another speaking, but they are not able to understand each other, and that is where the importance lies. Communication between computers is actually a little more complicated than that, but that will do for now. You’ll learn more of the subtleties of the TCP/IP protocol later in this chapter.

A computer network is all about sharing data and exchanging ideas. These fundamental practices on a network, however, pose certain security problems. There are many different types of security to be concerned with on a network, such as physical security, file and directory security, and Internet security, but one core section of security that is often overlooked is password security. When you share files or printers with other users, you sometimes are asked for a password. This password is a “key” that will either admit or restrict your access to the data or peripherals on the network. Password security is the practice of making sure that the passwords are difficult to break into. Several fundamental practices are used when trying to enforce password security on a network. You’ll learn more about the different practices of password security later in this chapter.

Standard Operating Procedures (SOPs) are the practices that you follow to enable your network to run smoothly and efficiently. These typically consist of backing up the data on the network, making sure everyone can communicate, and fixing any problem that may arise at a moment’s notice. It doesn’t get much simpler than that!

Administrative and Test Accounts

The network administrator holds the keys to the network castle. Any actions that the network administrator makes can ultimately affect those who are part of the network. The person who holds the Administrator account has complete, unrestricted access to all of the files, folders, and shares on the network. He has complete power over the security of the network.

Because the Administrator account is a sensitive issue, those with system privileges to the account should be very careful and restrict access to only those who truly need the account to complete their jobs. In no case should a person who has the capability to log in using the Administrator account use this for his day-to-day usage of the network. That is a good way to inadvertently enable a virus or an unwelcome user complete access to the network. Remember that you are dealing with the sensitive nature of your data and you should do whatever you can to protect it.

Basically, the Administrator account should be used to perform administrative duties only. All other duties should be completed when logged on with a personal user account. This practice allows for safe and restricted access to the sensitive areas of the network. The role of any network administrator is to protect the data on the network. With this role comes a lot of responsibility. As the administrator of the network, you essentially hold the data in the palm of your hand. If by some chance the Administrator account accidentally becomes compromised, you could leave the safety of your network in the hands of others. This, of course, is not what you want to do.

The administrative account is the most sensitive account on your network, so you have to be extra careful to use a password that is difficult to break. A password should consist of more than eight characters that include both upper- and lower-case letters as well as numbers or symbols. You should never use a simple phrase or word for the Administrator account.

Some operating systems, such as Windows NT Workstation and Server, allow for some flexibility with the Administrator account. For example, a good practice to follow is to immediately rename the Administrator account to something other than “Administrator.” If someone is trying to break in to your computer network, they need two very important things. One, they need the name of the account and two, they need the password for that account. If a potential hacker knows the name of an administrative account, he’s already half way to gaining access to your network. By renaming the Administrator account, you eliminate fifty percent of the problem right off the bat.

Another standard practice is to limit access to the Administrator account to those who have a justifiable need for the account. When the network administrator grants administrative access to too many people, there is no accountability on the network. You cannot be sure who is making changes on the network because so many different people have access.

The worst-case scenario is when people have administrative access to important files that would normally be restricted to them under their personal accounts. With administrative access, they can roam and browse any files on the network without anyone being able to do anything.

Whenever you make a change to any part of your network, you should verify that the change didn’t affect any other part of your network. You can accomplish this by using a test account to make sure that your change works. A test account is an account with normal rights within the network. If you used an administrative account to make the change, then you should use a test account to test your changes. This practice is especially important when making changes to file and directory permissions. When you have administrative privileges, you have access to everything on the network, so you can’t test to see your changes from the perspective of a normal user. By using a test account, you can make sure that you didn’t give too much freedom on the network and that your changes went according to plan.

Consider this example of the consequences when the test account practice is not followed: A network administrator made a change to the Payroll folder and its subdirectories on one of the shares on a server. Instead of using a test account to verify that his changes went through as planned, he moved on to something else. What he didn’t discover until later is that he accidentally gave everyone on the network access to the Payroll share. Anyone on the network could access the payroll files.

Table 8-1 lists the standard practices for administrative and test accounts on a network.

Administrative Account

Test Account

Maintain exclusive permissions for all files and folders on the network.

Set with sample user rights—this account should have restricted privileges on the network.

Set and enforce tight security for anyone who has administrative rights on the network.

 

Setup your test account to resemble all other accounts on your network including privileges and password security.

 

Assign a strong password with at least eight characters, using a mix of upper- and lowercase letters as well as numbers and symbols.

Assign a strong password.

Restrict access to the administrative account to those few people who need access.

Assign restricted privileges to the network.

Use this account to make any necessary changes to the network.

Use this account to test the changes that you made to the network. You are simulating a normal user with this account.

Table 1: Administrative and Test Accounts

Table 8-1 will help you remember the advantages and purpose of having two separate accounts on the network. Usually, a network administrator has an account with administrative privileges and one without. During the course of the day, the network administrator uses his administrative account for making any needed changes. For normal day-to-day usage, the network administrator uses his account that does not have administrative access to the entire network.

From the Field

The Importance of Having a Backup Administrator Account

I never realized the importance of having another account with administrative rights on the Windows NT network until I found myself in a particular bind one day. While logging on to my Administrator account, I was prompted that my password was set to expire soon. I changed my password, and that’s where the trouble began. I had forgotten that I was currently logged on to another server in the server room. When I changed my password, Windows NT became confused that I was logged on to the network with a username that now had two different passwords assigned to it. The result is that my account got locked out. My administrative account! I couldn’t figure out what had happened, until I discovered that I was logged on to the server in the server room.

I had no way to unlock my Administrator account because you must have administrative rights in order to modify an account with administrative rights. Of course, I couldn’t find my boss to ask him to unlock my account. When I paged my boss he told me to check the filing cabinet for a sealed envelope containing the logon information for the backup Administrator account. I used this backup account to unlock my account and enclosed the logon information in another sealed envelope. The sealed envelope is to detect whether the account information has been tampered with.

The moral of this story is to always have a backup Administrator account ready for emergencies. Another important lesson to be learned is to always log out of machines when you are done if you are using your account with administrative rights. Someone could tamper with information logged on as you, and it would appear that you were responsible. Finally, the last lesson to be learned is to never change your password on a Windows NT server or workstation if you are currently logged on to more than one machine. You account will instantly be locked out! Be careful when you are using an account with administrative rights—it’s very powerful!

                                 Cameron Brandon, MCSE+Internet, CNE, A+, Network+                                 

Passwords

Passwords are another form of computer security to ensure that those who aren’t supposed to access certain files on the network don’t. Passwords aren’t a fail-safe method of securing your network, but if they are implemented and enforced correctly, they can impose a level of security that you should feel comfortable with.

You can think of passwords in terms of a lock-and-key system. The user account is the lock and the password associated with that account is the key. If you have both the lock and the key for the network, you can have access to any files or data that the user account has access to. It’s as simple as that.

As the network administrator, it’s your job to enforce strong passwords on the network and across your computing environment. A strong password is a password that is difficult to “crack” or break in to. With the intelligence, experience, and technology of today’s hackers, it’s getting easier and easier for them to gain access to our files. Your job is to keep them from doing so.

Exam Watch: You should memorize what makes a secure and safe password. Make sure to eliminate the use of easily guessed words or phrases in your password!

A good way to approach password security is to think like a hacker. If I were a hacker, I’d like to break into an account with a nice and easy password that resembles a common phrase or easily guessed word or group or words. This is an absolute no-no for password security. If you want to enforce password security, you cannot, under any circumstances allow your users to create passwords that include their names, the names of relatives, birthdays, or common phrases. Today’s hackers use technology that is called “brute force” attacks that run different dictionary files against the user account in question in an attempt to break into that account. They are usually successful because the user decided to utilize a commonly guessed word or phrase, such as their favorite baseball team or their spouse’s birthday. Unfortunately, when you prevent users from choosing easily remembered passwords, some users are prone to compromise security even further by writing their password on a yellow sticky-note and posting it to their monitor. You must educate your users about the need for password security and institute a policy that prohibits them from posting their passwords or sharing passwords with other users.

You should require users to change their passwords frequently, such as every three to four weeks. Even the most secure and seemingly unbreakable passwords are not impervious to some high-quality hacking programs. Some hacking programs will run for a set period of time until the password is broken. On a standard Pentium 200MHz, it may take a program like this roughly three or four weeks running non-stop to break the password. If you require frequent password changes, by the time the hacker could compromise a user’s password, it is time to change the password anyway, effectively stopping the hacker’s progress.

On the Job: With all of the computer technology available to help secure your network, sometimes the weakest link in your network is the human factor. You can implement the strongest policies and use the latest technology available, but if your users fail to adhere to the rules and regulations regarding your network password policies, all of your work is for naught. To combat this problem, you might want to encourage your users to become better trained on the technology that they are using.

The last standard practice for enforcing password guidelines on your network is to enable password lockouts. In particular with the Microsoft Windows NT operating system, the network administrator can enable password lockout after x number of attempts to log in with an incorrect password. The network administrator specifies the duration of time that the account is locked. A reasonable amount of time is about 30 minutes. For example, if a hacker is attempting to break in to the network with a certain user account and he doesn’t know the password, after three unsuccessful attempts to log in, the user account that the hacker is trying to use is disabled for 30 minutes. This practice severely limits the ability of a hacker to keep trying different passwords on the same user account.

Table 8-2 provides guidelines that will help you to enforce strong passwords on your network.

Guideline       

Purpose

Password is at least eight characters long.

The more characters in a password, the more difficult it is to crack.

Password consists of both letters and numbers.

Passwords that contain a mix of letters and numbers defeat dictionary and “brute force” attacks by disrupting the pattern that these programs look for.

Password includes symbols (!, @, #, $, %, ^, &, *,).

The use of symbols helps complicate the password and disrupts the pattern looked for by dictionary and “brute force” programs.

Password does not consist of common words of phrases.

A dictionary program can easily crack passwords that consist of words or phrases.

Passwords are changed frequently.

Even a strong password can be cracked with time; changing a password frequently defeats any hacker that may have cracked the old password.

Lock user accounts after x number of attempts to log in with an incorrect password.

Account lockout prevents a hacker from running a program that repeatedly tries different passwords until finding the correct one.

Table 2: Strong Password Guidelines

Exam Watch: I know it seems obvious to specify passwords with a mixture of upper- and lowercase letters and the use of at least one symbol. The exam will test your knowledge of safe password practices by having you select the most secure password from a list of choices.

IP Addresses

TCP/IP (Transmission Control Protocol/Internet Protocol) is an industry-standard suite of protocols designed for local and wide area networking. TCP/IP was developed in 1969, in a Defense Advanced Research Projects Agency (DARPA) research project on network interconnection. Formerly a military network, this global area network has exploded and is now referred to as the Internet.

TCP/IP gained most of its popularity through its wide use for Internet communication. Connecting computers throughout the world, it is known for being both reliable and routable and for being able to talk to foreign networks.

Windows NT TCP/IP enables users to connect to the Internet as well as to any machine running TCP/IP and providing TCP/IP services. This includes some applications that require TCP/IP to function. The following list summarizes the advantages of the TCP/IP protocol:

       It is the backbone of the Internet. If you need to connect to the Internet, you will need TCP/IP.

       It is routable. This means that you can talk to other networks through routers.

       It is very popular. Think of all of the computers on the Internet.

       Some applications need TCP/IP to run.

       It provides connectivity across operating systems and hardware platforms. Windows NT can use an FTP client to access a UNIX workstation or server.

       It provides Simple Network Management Protocol (SNMP) support, which is used to troubleshoot problems on the network.

       It provides Dynamic Host Configuration Protocol (DHCP) support, which is used for Dynamic IP addressing.

       It provides Windows Internet Naming Service (WINS) support, which resolves Windows NetBios names on the network.

To configure a TCP/IP address on a computer, you need specific TCP/IP parameters. These parameters consist of a static TCP/IP address, a subnet mask, and a default gateway (router), if you are connecting to the Internet or another network. You can use either a static or DHCP-assigned TCP/IP address to connect to the Internet. If you are using a server to connect to the Internet, a static IP address makes more sense so you don’t have to continue to update your DNS tables.

An IP address can be thought of as a “house” address that you might see on the side of a building. Just as every house has a street address, city, and Zip code, every computer that uses the TCP/IP protocol has an IP address. This helps identify the computer on the network so that the computers can “talk” to one another. Each IP address can be configured for a separate subnet or network so that different computers can communicate with one another. A computer uses an IP address to identify itself on the network. Just as each and every house has an address associated with it, all computers on a network that uses TCP/IP must have an IP address. An IP address is a 32-bit address that is broken up into four parts, or octets.

In order for one computer to communicate with another computer, there must be a dialog in place in the form of a network protocol. Due to its popularity on the Internet, the TCP/IP protocol has become one of the most widely adopted network communication standards within the entire computer industry. To make matters much more complicated than they need to be for this exam, I’ll get into subnet masks. Because an IP address is actually a 32-bit address, a subnet mask helps separate the network from the host ID. The network ID identifies the network the computer resides on (similar to a ZIP code). The host ID identifies the specific computer (similar to a house address).

IP Configurations

The TCP/IP protocol has many different uses and many possible IP configurations. Your TCP/IP parameters determine how and what your TCP/IP configuration will be. IP configurations are ultimately determined by the network operating system that you are running on your desktop. For instance, some operating systems do not recognize Dynamic Host Configuration Protocol (DHCP). DHCP is used to automatically hand out an IP address and configuration from an open pool of TCP/IP addresses.

Table 8-3 shows examples of the many different TCP/IP parameters and the specifics of how they are used.

TCP/IP Parameters

Description

IP address

An IP address is a 32-bit network address that identifies a computer on a network. An IP address is made up of a network ID and a host ID.

An IP address is a four-octet address. Example. 204.22.120.3

Subnet mask

A subnet mask separates the network ID from the host ID. This can break down an individual IP address into different and separate logical networks or subnets.

Default gateway

A default gateway is actually a router that is used to send packets to remote networks. The default gateway that is configured will receive a packet from your computer and route the packet to its correct destination. Without a default gateway configured, your computer cannot communicate with any remote networks.

Domain Name System

A DNS Service is used to map IP addresses to fully qualified domain names (FQDNs). This form of name resolution is commonly used on the Internet to map IP addresses to popular web sites.

Windows Internet Naming Service

A WINS Service also provides name resolution for computers, but does so only for Windows computers and is normally “Microsoft centric.” A WINS Service maps IP addresses to NetBIOS names.

HOST file

A HOST file is an internal computer file that maps a computer’s host name to an IP address. This is commonly used when a name resolution service such as DNS or WINS is not available.

LMHOST file

An LMHOST file maps NetBIOS names to IP addresses.

MAC address

A MAC address is the physical network address of a computer’s network interface card. A MAC address is a 12-letter hexadecimal address that is broken up into two segments. The first six hex letters identify the vendor of the network card; the last six hex letters are the serial number that identifies the computer.

Dynamic Host Configuration Protocol

DHCP is used to automatically allocate TCP/IP address information to a computer that is “DHCP enabled.” This practice reduces the amount of administration necessary for large networks.

Host name

A host name or computer name uniquely identifies the computer on the network.  A host name or Fully Qualified Domain Name will uniquely identify a computer on the network or Internet, but a NetBIOS name is the computer name that is specified by the network administrator. These two names can be different, but unless changed, the Host name defaults to the NetBIOS computer name.

Table 3: TCP/IP Configuration Options

Name Resolution

Computers communicate with each other by using network addresses, but people tend to want to communicate by using computer names. It is much easier to remember a computer name than a set of four different numbers. A more intuitive solution has been introduced, so that people can communicate by using computer names instead of hard-to-remember network addresses. Names must be resolved to their respective network addresses. The two main options associated with name resolution on computer networks are Domain Name System (DNS) and Windows Internet Naming Service (WINS). For name resolution on Windows networks, WINS resolves NetBIOS names to TCP/IP addresses. For computers that use host names, DNS resolves fully qualified domain names (FQDNs) to TCP/IP addresses. This is what the Internet uses to keep track of all of the different names found on the Internet.

WINS

The Windows Internet Naming Service (WINS) was designed to eliminate the need for broadcasts to resolve NetBIOS names to IP addresses and to provide a dynamic database that maintains NetBIOS names to IP address mappings. (The computer name is just one of many NetBIOS names.) This type of name resolution was introduced by IETF as an RFC for the use of NetBIOS Name Servers (NBNS) to resolve NetBIOS names to IP addresses. WINS is Microsoft’s implementation of an RFC-compliant NBNS. The TCP/IP information is stored in a database on the WINS Service. Instead of network clients broadcasting for name resolution, the client contacts the WINS Service and the WINS Service informs the client of the correct address.

DNS

DNS (Domain Name System) maps TCP/IP addresses to computer names. Normally, computers communicate via their MAC addresses on a network. To communicate by name, the TCP/IP address must be resolved to a computer name. DNS maps TCP/IP addresses to computer host names on the network. DNS uses a distributed database over hundreds of different computers, resolving computer host names. This helps us locate computers all over the Internet. We type the DNS name of the server we want to access, and the DNS Service maps the correct TCP/IP address for us automatically. Sounds simple, right? These DNS root servers are managed by the Internet Network Information Center (InterNic). You are probably familiar with the DNS naming scheme: Microsoft.com, Cisco.com, Oracle.com, and Dell.com are all examples of DNS names.

Relevant SOPs

From network to network, many similar standard operating procedures are maintained. No matter which network you may visit, these procedures generally stay the same. The names of these procedures may change, but the duties that are involved in them are very similar. This section presents the most important standard operating procedures that you should follow on your own network.

Keep the network up and running at all times. This SOP is accomplished by many sub-procedures, such as backing up the data on the network, monitoring the performance of your servers, and performing common administration duties for the network.

Back up network data every night. This is one of the most important duties that a network administrator can perform. No matter how secure and stable your computer network is, events out of your control can bring down the network or accidentally destroy a server.

Monitor the performance of your servers and network infrastructure. This will help you to troubleshoot problems and to work proactively to prevent problems. The best way to troubleshoot a bottleneck on a server resource is to have monitored the performance of that resource so you have a “baseline” of the resource in day-to-day operation. You should also monitor the amount of traffic on the network. To do this, you can use a network sniffer, a network monitoring tool that analyzes the traffic on the network and can help you solve problems that are infrastructure related.

As a network administrator, you may have common duties such as securing the network, configuring network hardware, and managing users and permissions. The more comfortable you become with these daily SOPs, the more you can begin concentrating on other areas of network management, such as backing up your data and monitoring the performance of the network.

I want to connect two LAN segments that are using Ethernet and Token Ring.

Connect the two network segments with a switch. No one uses hubs anymore. Switched ports are cheap and they do a great job.

I want to connect two LAN segments in different geographical locations.

To connect LAN segments in different geographical locations, you need a router. A router can find the destination address of a packet and send the packet accordingly.

A user wants to connect his PC, which has an RJ-45 connector, with a computer that has a BNC connection.

Connect the PC with the RJ-45 connector to a hub and the BNC connection to another hub that supports both connections.

I want to connect a TCP/IP network to an IPX/SPX network.

Use a gateway to connect networks that are using two different protocols.

I have 10 PCs that all connect to one server. What do I need to support the bandwidth requirements?

All that you need is a simple hub. 10 PCs do not require too much bandwidth unless you are doing video.

My client has over 2500 computers in one geographic location. What network appliance would be right for this large a network?

With that size network you should utilize network switches and separate the computers into separate broadcast domains.

I want to connect two networks that are in the same location. Can I use a router?

A router can be used to connect networks that are in the same location, but for cost, you might want to pick a less expensive solution relative to the number of ports that are required. Generally, routers are more expensive per port than switches or hubs.

Environmental Factors that Affect Computer Networks

Most networks have a centrally located area that can safely house all of its network appliances and servers. Within this room is a multitude of special features that can help to protect the computers and other environmentally “sensitive” equipment from failing due to extreme temperatures.

Computers, like most other electrical hardware, are affected by temperature, moisture, vibrations, and electrical interference. If the computers are exposed to these elements, they can act irregularly and sometimes fail. Luckily, there are standards that protect computer components from these situations.

Cables

Underneath the protection of most network cables lies a fragile layer of wire (or glass, in the case of fiber optic) that carries the data from one computer to another. Like most other computer components, this wire is not resistant to moisture, heat, or other electrical interference. To protect this cable from harm, a covering is placed over the wire to protect it from breaking or accidentally becoming wet.

Cables that bring data to networks come in many different forms, from copper to fiber optic. The type of cable determines the length that it can be. When a cable exceeds the recommended distance, the signal begins to fade. Table 8-4 lists the types of cables, their characteristics, and the distance they can carry a signal.

Type of Cable

Characteristic

Length

10BaseT

Flexible, uses RJ-45 connector.

100 meters/328 feet

10Base2

Less flexible than 10BaseT, uses a BNC connector to hook computers together. Must be terminated on one end.

185 meters/607 feet

10Base5

Rigid, does not bend well around corners. Not used too often; AUI connector.

1640 feet

Fiber optic

Does not do well in tight changes of redirection. Carries data extreme distances. Easily broken, fragile.

2 kilometers

Table 4: Cabling Characteristics

Exam Watch: Make sure you know the cable length limitations for each type of cable. You will be presented with scenario questions where you are to determine if the configuration is valid—you have to know whether the maximum cable length has been exceeded. These questions are challenging because of the complex scenario-based format.

 The Network Operations Center

The Network Operations Center (NOC) is the home base for all of the important servers on your network. The NOC enables you to centrally manage and keep a close eye on all of your networked data.

An NOC, above all else, needs to be secure and able to house all of the data and servers. Normally in a locked room, the NOC is a secured room that is equipped with different types of fire suppression (Halon, Foam), raised floors to place the cabling, and temperature control. A price cannot be put on the value of your data, so this room should never be compromised in any way.

Room Conditions

The room conditions of your NOC should be cool, dry, and temperature controlled. Computers and other electrical equipment do not like humidity, heat, or extreme cold, so you should be very careful to regulate the temperature of your NOC. When a computer overheats, there is no guarantee that the data on your servers can be saved.

Because computer equipment is very sensitive to moisture, you need to use a form of fire suppression besides water. Putting out a fire in your NOS with a sprinkler system would ruin all of your computer equipment. There are many different types of foams or HALON used to put out fires quickly and safely, while minimizing the potential damage to your computer equipment.

Exam Watch: You will be asked to determine which environment is the most conducive to a server room. Just remember that servers need an environment free of dust, with plenty of ventilation, and reasonable temperature and humidity. Placing servers near a window on a sunny day or in a dusty warehouse would not create an ideal operating environment.

Minimizing Electrical Interference

Electromagnetic interference (EMI) can wreak great havoc on any type of computer equipment. You might be aware of certain types of speakers that are magnetically shielded to prevent electrical interference. However, magnets and computers don’t mix, so this concept unfortunately doesn’t mesh well. Your alternative to this is to keep all of your computer equipment away from any electrical device that may interrupt the computing power of your data.

Exam Watch: This question is more about common sense. Make sure you don’t expose your computers or network equipment to any potential environmental hazards, such as moisture or extreme heat, or to electrical interference, such as generators and televisions.

 Computer Chassis

With the boom of today’s technology, computers are faster than ever. Today there is more computing power on a single laptop computer than was used by NASA to place the first man on the moon. However, more computing power comes at a price. The price that we pay is heat. As processors become faster and faster, they are becoming hotter and hotter as they perform billions of calculations. The scenario is the same for disk drives as well. The larger the drives become, the more work that needs to be done to find the data on the drive. The result of this is the temperature within the PC’s chassis becomes too hot for the computer to operate. When this happens, the over-heating part will fail or destroy the PC altogether.

To combat this problem, a cooling fan was placed inside the PC to circulate the air and prevent the PC from overheating. Some computer chassis are becoming more inventive every year and help circulate the air inside the PC to keep the computer cool.

Error Messages

Error messages carry a mixed blessing in the computer industry. It’s great to know when you have an error, but some error messages are so vague and incomprehensible that they do nothing but confuse you further.

You will encounter many types of error messages in your day-to-day progress with computers. You will see syntax errors, general protection faults, memory dumps, Dr. Watson messages, error logs, .DLL conflicts, and several hundred others.

 When using your computer, you might inadvertently generate an error message. When your computer gives you an error message, it is letting you know that it cannot understand the data input or that an unexpected error has occurred. This is what happens during the error message process.

Some of the better-written and coded programs go out of their way to let you know what exactly is happening when you generate an error message. Seeing “Error Code 12452” flash across the screen doesn’t help too much unless you know exactly what “Error Code 12452” is. Chances are you don’t have any idea what that cryptic error message means.

If you are lucky, sometimes you will have the capability to look into the help file to find out what a vague error message might be. It helps a lot if you can check the vendor’s web site as well, because they may have an on-line support site specifically for those types of questions.

Some error messages are user friendly and will tell you exactly what you did wrong. For instance, if cannot print and you see the message “Incorrect Printer Driver, please Install Correct Driver,” you have a good idea as to what you might have done wrong and you will know how to fix your problem.

Table 8-5 lists some common error messages and their meanings.

Error Message

Description

Syntax error

You have entered information that your computer cannot understand. This is normally caused by a typo or an incorrect spelling of a desired command.

General protection fault

An overlapping memory block within your computer system causes a general protection fault. This is less common with secure operating systems, such as Windows NT, because they can compensate by not enabling any software direct access to the hardware and can run processes in separate memory spaces.

Blue Screen of Death

A common Windows NT error screen where the computer crashes, reboots, and dumps the error logs into a memory. If you are witnessing this screen, something major is not right.

Bad command or file name

Your computer does not understand what has been entered. You should make sure that you have the correct path and that the program or file that you want to access is in the specified directory.

File is listed as read only

You may see this error when trying to write to a file that is listed as read only. With this permission, you can only have read access to the file; you cannot change the file.

Access denied

This error message is self-explanatory. Your permissions do not match the necessary permissions to the file or directory.

Table 5: Common Error Messages

Common Peripheral Ports and Network Components

What good is a computer without all of the goodies? There are literally hundreds of peripherals and network components to choose from in today’s fun-filled world of computers. Here, you will learn the basics about the ones you will likely encounter in your day-to-day experience.

All of these ports and network components are mainly used to make the experience of using a computer easier and more user-friendly. If you are going to be an expert in networking technology, you should know and understand each component in case you have to troubleshoot a problem some day.

Network Interface Card

Your network interface card (NIC) should be auto-detected during setup, but if it is not, you must enter the IRQ, the I/O address, and the base memory address. If these settings are not correct, the network fails to start when you log on, and you receive a message while booting up that a service or driver failed to load. Usually, the hardware vendor for your card provides you with a network configuration diskette that tells you exactly what the settings should be. Verify these settings before you begin the setup process to save time. As you configure your card, you’ll be asked whether you are wired to the network or are connecting via the Remote Access Service (RAS). Make sure you refer back to Chapter 2, Physical Layer, and go over the lab for installing Network Interface Cards. 

Being Wired to the Network

Being part of a network is what networking is all about. Having access to thousands of files and applications that are just a click away is both convenient and efficient. In order for your web server to communicate with other computers on the network, you have to install a network interface card. This network card also has to be configured correctly with the TCP/IP protocol. The network card binds with the TCP/IP protocol to enable communication.

When you can communicate with other computers on the network, you are free to share files and information at the click of a button. This is what makes networking so special and one of the many reasons that computer networks are changing the face of business as we know it today.

Binding Different Protocols

Being wired to a network gives you connectivity to other computers and enables you to exchange information. However, each computer on a network generates a lot of traffic, and when you have a lot of computers on the network, an awful lot of traffic is generated. If you have more than one protocol installed for your NIC, your computer will try to use each protocol that is installed. For the best performance, you should have only the necessary protocols that you are going to be using on your network. Having more than one protocol installed creates extra traffic and more overhead for your network than is necessary.

Network Connection

Connecting to the Internet with a networked server requires a lot of bandwidth to provide connectivity for all users. The amount of bandwidth determines how many users can access your site at once. A fast network connection enables easy access to your web site, whereas, a slow connection sometimes prohibits users from getting to your web site. If you are on an intranet, you probably do not have to worry about the amount of bandwidth. A normal 10MB Ethernet network card should be sufficient.

To connect straight to the Internet, you need a router or default gateway so that others outside your network can access your site. If you do not want to use a dedicated router for your Internet connection, your Windows NT 4.0 Server can perform the same duties with proper configuration.

Serial Port

In computer terminology, serial means slow. With a serial port, such as that used by your keyboard or mouse, data can only flow in only one direction. This makes for slow data transfer. Your keyboard and mouse are one-way devices that require only a serial interface and line.

Parallel Port

Parallel ports are the quicker of the devices that are connected to the outside of your computer. Parallel transmission works by sending data in both directions (serial goes only one way). Your printer, for instance, uses a parallel cable to speed up the printing process.

Universal Serial Bus (USB)

Universal Serial Bus (USB), or fire-wire as it is typically called, is a new innovation in computer peripheral technology that enables you to add devices such as audio players, joysticks, keyboards, telephones, and scanners without having to add an adapter card or even having to turn the computer off. Sounds like a good idea, huh? Well, USB can even transfer data up to 12 Mbps and works by using the existing power of the computer so you don’t have to plug in any of your USB devices.

 SCSI

Small Computer System Interface (SCSI) is a standard interface that enables personal computers to communicate with peripheral hardware, such as disk drives, tape drives, CD-ROM drives, printers, and scanners. What makes SCSI devices so special is the improvement in data transfer over parallel devices. For example, the newest Ultra-Wide SCSI 2 devices can transfer data up to 80 Mbps. Another benefit of SCSI devices is the capability to daisy chain up to 7 or 15 devices (depending on the bus width). SCSI devices are more important for high-performance computing systems, such as servers, than they are for the home PC.

Interrupts

The operating system (OS) on your machine (probably a flavor of Windows), will set up the IRQs (interrupt request) lines that enable the OS to communicate with the different devices within your system, such as graphic cards, CD-ROM drives, network cards, and printers.

Your computer communicates to the different peripherals within your computer by using the IRQ's hardware lines that your computer uses to send input and output messages. These IRQs are assigned different priorities so that the microprocessor can determine which of the interrupts it’s receiving is the most important.

To simplify matters, when your computer needs to use a device such as a network card, the network card signals the CPU via the IRQ so that it can use the processing power of the CPU to do its work.

Print Servers

Print servers can be either dedicated servers that are responsible for sending documents to various printer pools that can be scattered around a corporation, or they can be used in tandem with  file servers. These servers are used to send documents to a server that takes care of the printing process. This makes much more sense than having a separate printer for each computer, and it gives you more control over administering the documents that are sent to each network printer.

Peripherals

With today’s booming computer industry, you have many options when choosing peripherals for your computer. The standard I/O devices, such as keyboard and mouse, are the mainstays for computer peripherals, but there are many other peripherals that you can utilize to make your PC experience even better.

Along with the boom of the Internet, modems have increased in speed and have brought millions of computers right inside your house.

Keyboard

A keyboard connects to the serial port of your computer and enables you to input data. Because the keyboard is the primary input device, you rely on the keyboard more than you think. The keyboard contains certain standard function keys, such as the Escape key, Tab key, cursor movement keys, Shift keys, and Control keys, and sometimes other manufacturer-customized keys, such as the Windows key.

Mouse

A mouse connects to the serial port of your computer and enables you to move a cursor around the GUI of your desktop operating system.

Printer

A printer outputs data on your computer to paper or other media, such as labels, transparencies, or envelopes.

Digital Camera

A digital camera is a new peripheral that enables the user to take pictures without film The pictures are saved as digital images and can be transferred to a computer for manipulation, enhancement, and distribution through means such as e-mailing and printing.

Modem

A modem (modulator/demodulator) is a communications device that enables a computer to talk to another computer through a standard telephone line. The modem converts digital data from the computer to analog data for transmission over the telephone line and then back to digital data for the receiving computer.

Bridge

Bridges are intelligent devices used to connect LANs. A bridge can also forward packets of data based on MAC addresses. They can filter traffic on a LAN. They determine the source and destination involved in the transfer of packets. They read the specific physical address of a packet on one network segment and then decide to filter out the packet or forward it to another segment.

Hub (Shared)

Hubs enable you to concentrate LAN connections. You can connect devices using twisted-pair copper media (UTP) to hubs to concentrate computers together. The limitation of unshielded twisted-pair (UTP) network cable is that it only has the capability to carry data one hundred meters before the signal begins to fade. To strengthen the signal, a hub is used. It also depends on what type of technology you are using. You can have either Token Ring hubs or Media Access Units (MAUs) or have standard Ethernet hubs.

Because most modern networks use UTP for installation, you need to learn the standards that an Ethernet hub is used for. If you have a network that has to cover a large physical location, you have to remember that one piece of UTP cable can only reach 100 meters. This severely limits what you can do with your network unless you use hubs.

Table 8-6 describes some benefits of using hubs in a networked environment:

Benefit

Description

Hubs centralize monitoring and administration.

Most “managed” hubs come with special monitoring and optimization tools that can be used to let you know if you are having a problem. You can also see the performance level of the throughput of your network.

Hubs enable easy expansion, because you can daisy chain several hubs to form one large hub.

If you want to expand your hub capacity, all you have to do is daisy chain a separate hub to create one, large managed hub.

Hubs enable you to use several different ports that can connect to several different resources.

With hubs, you can utilize different ports for on-site administration and connect different media, such as a coax segment with a UTP segment of your network.

Hubs provide a high level of fault tolerance.

By having several wires coming into a hub, if one wire fails, it will not affect any of the other wires that are linked to the hub.

Hubs expand the length of your network.

Due to the limitation of UTP (100 meters), you may have to use hubs to boost the strength of the signal to connect segments of your network.

Hubs enable you to connect multiple users together to form one network.

This works with the star topology where the clients are connected to a hub in the “star.”

Table 6: Benefits of Using Hubs in a Networked Environment

Switch

Switches offer full-duplex dedicated bandwidth to LAN segments or desktops. You can think of a switch as an intelligent hub that guarantees that amount of bandwidth to the computer that it is connected to. This of course would depend on which port you a reconnected to; 10, 100 or 1000 Mbps. With a hub, you are guaranteed some of the bandwidth all of the time. This means that hubs are not intelligent enough to account for collisions on the network; you may be connected to a 10MB port, but you may only be receiving 4 megabytes of data because of the amount of traffic on the network. With a switch, you are guaranteed the entire limit of your bandwidth because the switch is intelligent and can examine the packet and send it in the right direction.

On the Job: Today’s computer networks have to support the combination of voice, video, and data, so many network administrators are beginning to favor intelligent switches over common shared hubs. Network switches enable you to have bandwidth on demand and ensure that you can use your network to the fullest capacity. If you have a switch that is capable of 100 Mbps, you are guaranteed that amount of bandwidth due to the way a switch can intelligently look at the packets. A shared hub, on the other hand, can sometimes supply only 40% of the potential bandwidth on the network.

Router

Routers route data packets across a network by opening the packet and making routing decisions based on the contents. As you learned earlier in this chapter, TCP/IP addresses enable communication between computers. Well, in order for different and remote computer networks to talk to one another, a device is needed to guide the TCP/IP network traffic to its destination. This is where routers come in and perform their duties.

Remember the OSI Model that you learned in Chapter 3? Well, to better understand the functions of routers, you should have a good understanding of the Network Layer of the OSI Model. The Network Layer, or Layer 3, is responsible for addressing messages and translating their logical addresses into an actual physical address. It is important to remember that a router is protocol dependent. That means that a TCP/IP router can connect to a TCP/IP network. In other words, this is the layer of the OSI Model that is responsible for determining where to send the TCP/IP packets to their destination. Routers essentially separate different broadcast domains from one another and route traffic based on its destination, or Layer 3, address (the Layer 2 address is the MAC address).

When you want to communicate with another computer network, your computer essentially looks within the local network first before heading out to search for a remote address. For example, when your computer needs to access a file on another computer, your computer first checks its ARP cache (Address Resolution Protocol) to see if that computer has a recognizable MAC address. If it does not, then your computer checks the local subnet by either broadcasting or asking a Name server for help.

If the address is not found on the local subnet or network, your computer checks to see if you have a default gateway or router to send the information to. Your computer sends this information to your router and the router routes the message accordingly. What happens is that the router receives the data with the address information and checks its routing tables to see where it should send your data. The type of router sometimes affects how quickly your data arrives at its destination.

Routers are either static or dynamic. Nine times out of ten, you’ll only have to deal with a dynamic router—a router whose routing tables are populated automatically by receiving updates from other routers. Static routers have fixed routing tables that have to be updated manually. These static routers are at a disadvantage because they cannot communicate with any type of router in case a network route changes due to hardware failure or change to the network layout.

The main benefit of a dynamic router is that, depending on which type of routing protocol is used, it will attempt to route your network traffic to your destination as quickly as possible. For example, if you have a network that is standardized on Cisco routers (dynamic) that all communicate with one another using the OSPF (Open Shortest Path First) routing protocol. All of your routers are communicating with one another via broadcasts that they send whenever there is a change in their routing. This comes in very handy and adds a layer of redundancy so that if a segment of the network fails, your routers will be able to route the network traffic to other paths so that no matter what happens to the network, your data will always arrive at its destination.

If you were using a static router and you had a segment fail on your network, your network traffic would cease until the segment was repaired or another static route was mapped on the router. This puts static routing at a severe disadvantage in a large, complex network environment.

Table 8-7 lists some of the characteristics of routers and what separates them from other network appliances.

Router Characteristic

Explanation

Protocol dependent

Routers are usually dependent on one protocol. A TCP/IP router cannot communicate with an IPX router.

Can communicate with other networks

A router works at the Network Layer of the OSI Model. It reads the destination of the packet and then sends the packet on its way to the destination network.

Used to connect to the Internet

By using a router, you can communicate with various remote networks such as the ever-popular Internet.

Can connect to different types of media, such as Ethernet and Token Ring

Some routers can connect two different networks, such as an Ethernet to a Token Ring connection or an ATM to an Ethernet. Normally, these routers work in the traditional way, but might have one or two ports to connect to different media.

Works at the Network layer, or Level 3, of the OSI Model

Routers work at the Network Layer of the OSI Model. This means that they can identify where the packet is coming from and then send the packet off to the correct destination.

Two different types, static and dynamic routers

Static routers have fixed routing tables that must be updated manually. Dynamic routers work by sending out broadcasts of their routing tables to other routers. This way, routers can change the path of a packet dynamically to work around a “downed” link.

Table 7: Router Characteristics

Gateway

A gateway can link networks that have different protocols, such as TCP/IP to IPX/SPX. A gateway can change an entire protocol stack into another or provide protocol conversion and routing services between computer networks. Gateways examine the entire packet and then  translate the incompatible protocols so that each network can understand the two different protocols. For example, protocol gateways can also be used to convert ATM cells to Frame Relay frames and vice versa.

Compatibility and Cabling Issues

All network cables are not created equal. There are four different types of commonly used network cables: thicknet (10B5), thinnet (10B2), twisted pair, and fiber optic. For most of your networking needs, twisted pair is the cable of choice, because it is relatively inexpensive and available. It is also easy to run in tight places and many standards are adopted for its RJ-45 interface.

Twisted-pair cables come in many different types with varying degrees of reliability. They are ranked in categories based on the proven level of data they can carry.

 

Cable Level

Maximum Data Bandwidth

CAT 1

 

CAT 3

10MB compatible

CAT 5

100MB compatible

CAT 5 Level 7

1GB compatible

Basically, if you have two different types of cables and you need to connect them, you need a hub, router, or switch to insert your cable into the correct port.

Incompatibilities with Analog Modems and a Digital Jack

An analog modem and a digital jack will not work together because they are two different technologies. An analog modem works over a standard phone line, and a digital jack for ISDN works with a digital PBX switch, not an analog phone switch.

Uses of RJ-45 Connectors with Different Cabling

An RJ-45 connector is used to connect segments of twisted-pair cabling. To connect two different types of media cable, you need either a hub or a bridge that has a specific connection for this type of cabling. For example, you can connect a 10BaseT cable that plugs into a bridge that supports connectivity with a BNC connector for 10Base2. You have to have the correct network hardware to connect the two different types of cabling media There are no other options for connecting an RJ-45 connection to a BNC connector.

Patch Cables and Length of the Cabling Segment

A patch cable of 10BaseT is normally a couple of feet long, or however long you need. Commonly, a patch cable is used to “patch” the length it takes to get from your network card to the digital jack at the floor of your office.

Certification Summary

The information covered in this chapter is directly related to the material you will be tested on in the Knowledge of Networking Technology part of the Network+ exam. The detailed explanations in this book will make you better prepared to pass the exam. The information presented here is taken directly from the requirements listed for this exam and our approach is to explain what will be covered on the exam and to summarize the key points you'll need to understand when taking the exam.

Becoming familiar with the different networking components is one of your best ways of preparing for this exam. By understanding common networking practices, you will be better prepared to install your own network and troubleshoot problems that you might encounter in the process. Experience is the true test of knowledge and having a sound fundamental base of the networking basics is a great place to start.

Now that you have a firm grasp on networking fundamentals, you need to know more about network administration and how a network operates. Part of this process is becoming used to the standard procedures that make up most networks. Another part of networking that you should be aware of for the test is network administration. This involves making sure that you understand the day-to-day duties that a network administrator must deal with, from configuring TCP/IP to solving common network problems.

As well as understanding the different networking concepts that an administrator has to perform, you have to gain a broader perspective of networking in general. This includes understanding the different environmental factors that can affect computer performance such as temperature, moisture, and electrical interference. You should also know and understand the standard operating procedures of a Network Operations Center (NOC) such as backup procedures, handling user accounts, and managing users and groups.

Besides having a firm grasp on the fundamentals of computers, becoming well rounded in the realm of computers is also needed.  Most likely you’re not going to be sitting at a desk eight hours a day, so you’ll need to know the insides of a computer from IRQ settings to the different peripherals and why you need to use them.

As you gain more experience with computers and networking in general, you’ll become more comfortable with the many different concepts of troubleshooting, administration, and operating procedures.