Troubleshooting of Network devices & Topology

Troubleshooting  of  Network devices & Topology

·         Troubleshooting and Supporting the Network

·         Predicting the Impact of Modifying, Adding, or Removing Network Services

·         Adding, Modifying, or Removing DHCP

·         Adding, Modifying, or Removing WINS

·         Adding, Modifying, or Removing DNS

·         Identify and Troubleshoot Errors with a Particular Physical Topology

·         Star Topology

·         Ring Topology

·         Bus Network Errors

·         Mesh Network Errors

·         Infrastructure Troubleshooting

·         Troubleshooting Network Media

·         Troubleshooting Infrastructure Hardware

·         Troubleshooting a Wireless Infrastructure

·         Wireless Signal Quality

·         Wireless Channels

·         SSIDs

·         WEP Settings

·         Wireless AP Coverage

·         Troubleshooting Steps and Procedures

·         Identify the Symptoms and Potential Causes

·         Identifying the Affected Area

·         Establishing What Has Changed

·         Selecting the Most Probable Cause of the Problem

·         Implement an Action Plan and Solution Including Potential Effects

·         Testing the Results

·         Identify the Results and Effects of the Solution

·         Documenting the Solution

Troubleshooting and Supporting the Network

Many duties and responsibilities fall under the umbrella of network administration. Of all these, one of the most practiced is that of troubleshooting. No matter how well a network is designed and how many preventative maintenance schedules are in place, troubleshooting will always be necessary. Because of this, network administrators have to develop those troubleshooting skills.

This tutorial focuses on all areas of troubleshooting, including troubleshooting best practices and some of the tools and utilities you'll use to assist in the troubleshooting process. To start, we'll look at the impact of modifying network services.

Predicting the Impact of Modifying, Adding, or Removing Network Services

All network services require a certain amount of network resources in order to function. The amount of resources required depends on the exact service being used. Before implementing or removing any service on a network, it is very important to understand the impact that these services can have on the entire network. To provide some idea of the demands various services place on the network, this section outlines some of the most common network services and the impact their addition, modification, or removal might have on the network and clients.

Adding, Modifying, or Removing DHCP

DHCP automatically assigns TCP/IP addressing to computers when they join the network and automatically renews the addresses before they expire. The advantage of using DHCP is the reduced number of addressing errors, which makes network maintenance much easier.

One of the biggest benefits of using DHCP is that the reconfiguration of IP addressing can be performed from a central location, with little or no effect on the clients. In fact, you can reconfigure an entire IP addressing system without the users noticing. As always, a cost is associated with everything good, and with DHCP, the cost is increased network traffic.

You know what the function of DHCP is and the service it provides to the network, but what impact does the DHCP service have on the network itself? Some network services can consume huge amounts of network bandwidth, but DHCP is not one of them. The traffic generated between the DHCP server and the DHCP client is minimal during normal usage periods.

The bulk of the network traffic generated by DHCP occurs during two phases of the DHCP communication process: when the lease of the IP address is initially granted to the client system and when that lease is renewed. The entire DHCP communication process takes less than a second, but if there are a very large number of client systems, the communication process can slow down the network.

For most network environments, the traffic generated by the DHCP service is negligible. For environments in which DHCP traffic is a concern, you can reduce this traffic by increasing the lease duration for the client systems, thereby reducing communication between the DHCP client and the server.

If the DHCP service has to be removed, it can have a significant impact on network users. All client systems require a valid IP address to get onto the network. If DHCP is unavailable, each client system would need to be configured with a static IP address. Because DHCP IP addressing is automatic and does not assign duplicate IP addresses, as sometimes happens with manual entries, DHCP is the preferred method of network IP assignment.

If DHCP is added to a network, all client systems will need to be configured to use DHCP. In a Windows environment, this is as easy as selecting a radio button to use DHCP. If client systems are not configured to use the DHCP server, they will not be able to access the network.

Adding, Modifying, or Removing WINS

WINS is used on Microsoft networks to facilitate communications between computers by resolving NetBIOS names to IP addresses. Each time a computer starts, it registers itself with a WINS server by contacting that server over the network. If that system then needs to contact another device on the network, it can contact the WINS server to get the NetBIOS name resolved to an IP address.If you are thinking about not using WINS, you should know that the alternative is for computers to identify themselves and resolve NetBIOS names to IP addresses via broadcasts. Broadcasts are inefficient because all data is transmitted to every device on the network segment. Broadcasts can be a significant problem for large network segments. Also, if a network has more than one segment, you cannot browse to remote segments because broadcasts are not typically forwarded by routers, which will eliminate this method of resolution.

Because WINS actually replaces the broadcast communication on a network, it has a positive impact on network resources and bandwidth usage. This does not mean that WINS does not generate any network traffic just that the traffic is more organized and efficient. The amount of network traffic generated by WINS clients to a WINS server is minimal and should not have a negative impact in most network environments.

WINS server information can be entered manually into the TCP/IP configuration on a system, or it can be supplied via DHCP. If the WINS server addresses change and the client configuration is being performed manually, each system needs to be reconfigured with the new WINS server addresses. If you are using DHCP, you need to update only the DHCP scope with the new information.

Removing WINS from a network increases the amount of broadcast traffic and can potentially limit browsing to a single segment unless another method of resolution (such as the use of the statically maintained LMHOSTS file) is in place.

Adding, Modifying, or Removing DNS

The function of DNS is to resolve hostnames to IP addresses. Without such a service, network users would have to identify a remote system by its IP address rather than by its easy-to-remember hostname.

Name resolution can be provided dynamically by a DNS server, or it can be accomplished statically, using the HOSTS file on the client system. If you are using a DNS server, the IP address of the DNS server is required. DNS server addresses can be entered manually, or they can be supplied through a DHCP server.

Identify and Troubleshoot Errors with a Particular Physical Topology

Each of the physical network topologies requires its own troubleshooting strategies and methods. When troubleshooting a network, it is important to know which topology is used as it can greatly impact the procedures used to resolve any problems. This section lists each of the respective physical network topologies and some common troubleshooting strategies.

Star Topology

The most common topology used today is the star topology. The star topology uses a central connection point such as a hub in which all devices on the network connect. Each device on the network uses its own length of cable, thus allowing devices to be added or removed from the network without disruption to current network users. When troubleshooting a physical star network, consider the following:

·         The central device, hubs or switches, provides a single point of failure. When troubleshooting a loss of connectivity for several users, it might be a faulty hub. Try placing the cables in a known working hub to confirm.

·         Hubs and switches provide light-emitting diodes (LEDs) that provide information regarding the port status. For instance, by using the LEDs, you can determine whether there is a jabbering network card, whether there is a proper connection to the network device, and whether there are too many collisions on the network.

·         Each device, printer, or computer connects to a central device using its own length of cable. When troubleshooting a connectivity error in a star network, it might be necessary to verify that the cable works. This can be done by swapping the cable with a known working one or using a cable tester.

·         Ensure that the patch cables and cables have the correct specifications.

Figure 1 shows how a single cable break would affect other client systems on the network.

Figure 1 Identifying cable breaks in a star network.

Ring Topology

Although not as commonly used as it once was, you might find yourself troubleshooting a ring network. Most ring networks are logical rings, meaning that each computer is logically connected to each other. A physical ring topology is a rare find but a Fiber Distributed Data Interface (FDDI) is often configured in a physical ring topology. A logical ring topology uses a central connecting device as with a star network called a multistation access unit (MSAU). When troubleshooting either a logical or physical ring topology, consider the following:

• A physical ring topology uses a single length of cable interconnecting all computers and forming a loop. If there is a break in the cable, all systems on the network will be unable to access the network.
• The MSAU on a logical ring topology represents a single point of failure. If all devices are unable to access the network, it might be that the MSAU is faulty.
• Verify that the cabling and connectors have the correct specifications.
• All Network Interface Cards (NICs) on the ring network must operate at the same speed.
• When connecting MSAUs in a ring network, ensure that the ring in and ring out configuration is properly set.

Figure 2 shows how a single cable break would affect other client systems on a physical ring network.

Figure 2 Identifying cable breaks in a physical ring network.

Bus Network Errors

Troubleshooting a bus network can be a difficult and frustrating task. The following list contains a few hotspots to be aware of when troubleshooting a bus network:

• A bus topology must be continuous. A break in the cable at any point will render the entire segment unusable. If the location of the break in the cable is not apparent, you can check each length of cable systematically from one end to the other to identify the location of the break, or you can use a tool such as a time domain reflectometer, which can be used to locate a break in a cable.
• The cable used on a bus network has two distinct physical endpoints. Each of these cable ends requires a terminator. Terminators are used to absorb electronic signals so that they are not reflected back on the media, compromising data integrity. A failed or missing terminator will render the entire network segment unusable.
• The addition, removal, or failure of a device on the network might prevent the entire network from functioning. Also, the coaxial cable used in a bus network can be damaged very easily. Moving cables in order to add or remove devices can cause cable problems. The T connectors used on bus networks do allow devices to be added and removed without necessarily affecting the network, but care must be taken when doing this.
• One end of the bus network should be grounded. Intermittent problems or a high occurrence of errors can indicate poor or insufficient grounding.

Figure 3 shows how a single cable break would affect other client systems on a bus network.

Figure 3 Identifying cable breaks in a bus network.

Mesh Network Errors

A mesh topology offers high redundancy by providing several paths for data to reach its destination. In a true mesh network, each device on the network is connected to every other device, and if one cable fails, there is another to provide an alternative data path. Although a mesh topology is resilient to failure, the number of connections involved can make a mesh network somewhat tricky to troubleshoot.

When troubleshooting a mesh network, consider the following points:

·         A mesh topology interconnects all devices on the network, offering the highest level of redundancy of all the topologies. In a pure mesh environment, all devices are directly connected to all other devices. In a hybrid mesh environment, some devices are connected only to certain others in the topology.

·         Although a mesh topology can accommodate failed links, mechanisms should still be in place so that failed links are detected and reported.

·         Design and implementation of a true mesh network can be complex and often requires specialized hardware devices.

Infrastructure Troubleshooting

No doubt, you will find yourself troubleshooting wiring and infrastructure problems less frequently than you'll troubleshoot client connectivity problems and thankfully so. Wiring- and infrastructure-related problems can be very difficult to trace, and sometimes a very costly solution is needed to remedy the situation. When troubleshooting these problems, a methodical approach is likely to pay off.

A network infrastructure refers to the physical components that are used to create the network. This includes the media used, switches, routers, bridges, patch panels, hubs and so on.

When troubleshooting the infrastructure it is important to know where these devices are on the network and what they are designed to do. In this section we explore two essential infrastructure components, media and hardware components.

Troubleshooting Network Media

The physical connections used to create the networks are sometimes at the root of a network connectivity error. Troubleshooting wiring involves knowing what wiring your network uses and where it is being used. When troubleshooting network media consider:

Media range (attenuation) All cables used in networking have certain limitations, in terms of distance. It might be that the network problems are a result of trying to use a cable in an environment or a way for which it was not designed. For example, you might find that a network is connecting two workstations that are 130 meters apart with Category 5 UTP cabling. Category 5 UTP is specified for distances up to 100 meters, so exceeding the maximum cable length can be a potential cause of the problem. The first step in determining the allowable cable distance is to identify the type of cable used. Determining the cable type is often as easy as reading the cable. The cable should be stamped with its type whether it is, for example, UTP Category 5, RG-58, or something else.

EMI and crosstalk interference Copper-based media is subject to the effects of EMI and crosstalk interference. UTP cables are particularly susceptible to EMI caused by devices such as power lines, electric motors, fluorescent lighting and so on. Consider using plenum rated cable in environments where cables are run through areas where EMI may occur. This includes heating ducts, elevator shafts and through ceilings around lighting fixtures. Crosstalk occurs when cables are run in close proximity and the signals from one interfere with the signals on the other. This can be hard to troubleshoot and isolate, so when designing a network ensure that crosstalk preventative measures are taken.

Throughout limitations A problem with a particular media may be simply that it cannot accommodate the throughout required by the network. This would create network-wide bottlenecks. It may be necessary to update the network media to correct the problem, for instance, upgrading the network backbone to fiber optic media.

Media connectors Troubleshooting media requires verifying that the connectors are correctly attached. In the case of UTP or coaxial, sometimes it may be necessary to swap out a cable with a known working one to test. For fiber, different types of connectors are used in fiber optic cabling. Before implementing a fiber solution, ensure that the switches and routers used match with the connectors used with the fiber optic cable.

Troubleshooting Infrastructure Hardware

If you are looking for a challenge, troubleshooting hardware infrastructure problems is for you. It is often not an easy task and usually involves many processes, including base lining and performance monitoring. One of the keys to identifying the failure of a hardware network device is to know what devices are used on a particular network and what each device is designed to do. Some of the common hardware components used in a network infrastructure are shown in Table 1.

Table 1 Common network hardware components, their function and troubleshooting strategies.
Networking Device Signs	Function	Troubleshooting and Failure
Hubs	Hubs are used with a star network topology and UTP cable to connect multiple systems to a centralized physical device.	Because hubs connect multiple network devices, if many devices are unable to access the network, the hub may have failed. When a hub fails, all devices connected to it will be unavailable to access the network. Additionally, hubs use broadcasts and forward data to all the connected ports increasing network traffic. When network traffic is high and the network is operating slowly, it may be necessary to replace slow hubs.
Switches	Like hubs, switches are used with a star topology to create a central connectivity device.	The inability of several network devices to access the network may indicate a failed switch. If the switch fails, all devices connected to the switch will be unable to access the network. Switches forward data only to the intended recipient allowing them to better manage data than hubs.
Routers	Routers are used to separate broadcast domains and to connect different networks.	If a router fails, network clients will be unable to access remote networks connected by the router. For example, if clients access a remote office through a network router and the router fails, the remote office would be unavailable. Testing router connectivity can be done using utilities such as ping and tracert.
Bridges	Bridges are commonly used to connect network segments within the same network. Bridges manage the flow of traffect between these network segments.	A failed bridge would prevent the flow of traffic between network segments. If communication between network segments has failed, it may be due to a failed bridge.
Wireless Access Points	Wireless access points provide the bridge between the wired and wireless network.	If wireless clients are unable to access the wired network, the WAP may have failed. However, there are many configuration settings to verify first.

Troubleshooting a Wireless Infrastructure

Wireless networks do not require physical cable to connect computers; rather, they use wireless media. The benefits of such a configuration are clear users have remote access to files and resources without the need for physical connections. Wireless networking eliminates cable faults and cable breaks. It does, however, introduce its own considerations such as signal interference and security.

Wireless Signal Quality

Because wireless signals travel through the atmosphere, they are subjected to environmental factors that can weaken data signals. Everything from electrical devices, storms, RF interference, and obstacles such as trees can weaken wireless data signals. Just how weakened the signal becomes depends on many factors; however, all of these elements serve to decrease the power of the wireless signal.

If you are troubleshooting a wireless connection that has a particularly weak signal, there are a few infrastructure changes that can be done to help increase the power of a signal.

·         Antenna Perhaps the first and most obvious thing to check is to ensure that the antenna on the wireless access point is positioned for best reception; this will often take a little trial and error to get the placement right. Today's wireless access cards commonly ship with diagnostic software that displays signal strength.

·         Device Placement One of the factors that can degrade wireless signals is RF interference. Because of this, it is important to try and keep wireless devices away from appliances that output RF noise. This includes devices such as microwaves, certain cordless devices using the same frequency, and electrical devices.

·         Network Location Although there might be limited choice, as much as possible, it is important to try to reduce the number of obstructions that the signal must pass through. Every obstacle strips a little more power from the signal. The type of material a signal must pass through also can have a significant impact on the signal integrity.

·         Boost Signal If all else fails, it is possible to purchase devices such as wireless repeaters that can amplify the wireless signal. The device takes the signal and amplifies it so that the signal has greater strength. This will also increase the distance that the client system can be placed from the WAP.

In order to successfully manage the wireless signals, you will need to know the wireless standard that you are using. The standards that are used today specify range distances, RF ranges, and speeds. It might be that the wireless standard is not capable of doing what you need. Table 2 highlights the characteristics of common wireless standards.

Table 2 Comparing Wireless Standards
Standard	Speed	Range	Frequency	Concerns
802.11a	Up to 54Mbps	2575 feet	5GHz	Not compatible with 802.11g or 802.11b
802.11b	Up to 11Mbps	Up to 150 feet	2.4GHz	Might conflict with other devices using the 2.4GHz range
802.11g	Up to 54Mbps	Up to 150 feet	2.4GHz	Might conflict with other devices using the 2.4GHz range
Bluetooth	720Kbps	33 feet	2.4GHz	Might conflict with other devices using the 2.4GHz range

As you can see in Table 2, the speeds are listed with the "Up to" disclaimer. This is because each standard will decrease the data rate if there is interference. 802.11b wireless link offers speeds up to 11Mbps, but it will automatically back down from 11Mbps to 5.5, 2, and 1Mbps when the radio signal is weak or when interference is detected. 802.11g auto sensing rates are 1, 2, 5.5, 6, 9, 12, 18, 24, 36, 48, and 54 Mbps. Finally, 802.11a provides rates up to 54Mbps, but will automatically back down to rates 48, 36, 24, 18, 12, 9, and 6Mbps.

Wireless Channels

RF channels are important parts of wireless communications. A channel is the frequency band used for the wireless communication. Each standard specifies the channels that can be used. The 802.11a standards specifies radio frequencies ranging between 5.15 and 5.875GHz. In contrast, 802.11b and 802.11g standards operate between the 2.4 to 2.497GHz range. As far as channels are concerned, 802.11a has a wider frequency band, allowing more channels and therefore more data throughput. As a result of the wider band, 802.11a supports up to eight non overlapping channels. 802.11b/g standards use the smaller band and support only up to three non overlapping channels.

It is recommended that the non overlapping channels be used for communication. In the United States, 802.11b/g uses 11 channels for data communication as mentioned three of these, channels 1, 6, and 11, are non overlapping channels. Most manufacturers set their default channel to one of the non overlapping channels to avoid transmission conflicts. With wireless devices, you have the option of selecting which channel your WLAN operates on in order to avoid interference from other wireless devices that operate in the 2.4GHz frequency range.

When troubleshooting a wireless network, be aware that overlapping channels can disrupt the wireless communications. For example, in many environments, APs are inadvertently placed closely together. Perhaps two access points in separate offices are located next door to each other or between floors. Signal disruption will result if there is channel overlap between the access points. The solution here is to try and move the access point to avoid the problem with the overlap or change channels to one of the other non overlapping channels. For example, switch from channel 6 to channel 11.

As far as troubleshooting is concerned, you would typically only change the channel of a wireless device if there is a channel overlap with another device. If a channel must be changed, it must be changed to another non overlapping channel.

SSIDs

The Service Set Identifier (SSID) is a configurable client identification that allows clients to communicate to a particular base station. In application, only clients that are configured with the same SSID can communicate with base stations having the same SSID. SSID provides a simple password arrangement between base stations and clients.

As far as troubleshooting is concerned, if a client is not able to access a base station, ensure that both are using the same SSID. Incompatible SSIDs are sometimes found when clients move computers, such as laptops, between different wireless networks. They obtain an SSID from one network and then if the system is not rebooted, the old SSID won't allow communication to a different base station.

WEP Settings

The Wired Equivalent Privacy (WEP) is a security protocol for wireless networks that encrypts transmitted data. WEP is easy to configure with only three possible security options Off (no security), 64-bit (basic security), and 128-bit (stronger security). WEP is not difficult to crack, and using it reduces performance slightly.

If your network operates with WEP turned off, your system is very open for someone to access your data. Depending on the sensitivity of your data, you can choose between the 64-bit and 128-bit encryption. Although the 128-bit WEP encryption provides greater security, it does so at a performance cost. 64-bit offers less impact on system performance and less security.

As far as troubleshooting is concerned, in order for wireless communication to take place, wireless devices must all use the same WEP setting. Most devices are set to Off by default; if changed, all clients must use the same settings.

Wireless AP Coverage

Like any other network media, APs have a limited transmission distance. This limitation is an important consideration when deciding where an AP should be placed on the network. When troubleshooting a wireless network, pay close attention to the distance that client systems are away from the AP.

When faced with a problem in which client systems cannot consistently access the AP, you could try moving the AP to better cover the area, but then you might disrupt access for users in other areas. So what can be done to troubleshoot AP coverage?

Depending on the network environment, the quick solution might be to throw money at the solution and purchase another access point, cabling, and other hardware, and expand the transmission area through increased hardware. However, there are a few things to try before installing another wireless access point. The following list starts with the least expensive solution to the most expensive.

·         Increase transmission power Some access points have a setting to adjust the transmission power output. By default, most of these settings will be set to the maximum output; however, it is worth verifying just in case. As a side note, the transmission power can be decreased if trying to reduce the dispersion of radio waves beyond the immediate network. Increasing the power would provide clients stronger data signals and greater transmission distances.

·         Relocate the AP When wireless client systems suffer from connectivity problems, the solution might be as simple as relocating the WAP to another location. It might be that it is relocated across the room, a few feet, or across the hall. Finding the right location will likely take a little trial and error.

·         Adjust or replace antennas If the access point distance is not sufficient for some network clients, it might be necessary to replace the default antenna used with both the AP and the client with higher end antennas. Upgrading an antenna can make a big difference in terms of transmission range.Unfortunately,not all WAPs have replaceable antennas.

·         Signal amplification RF amplifiers add significant distance to wireless signals. An RF amplifier increases the strength and readability of the data transmission. The amplifier provides improvement of both the received and transmitted signals, resulting in an increase in wireless network performance.

·         Use a repeater Before installing a new AP, you might want to first think about a wireless repeater. When set to the same channel as the AP, the repeater will take the transmission and repeat it. So, the WAP transmission gets to the repeater, and then the repeater duplicates the signal and passes it forward. It is an effective strategy to increase wireless transmission distances.

Troubleshooting Steps and Procedures

Regardless of the problem, effective network troubleshooting follows some specific troubleshooting steps. These steps provide a framework in which to perform the troubleshooting process and, when followed, can reduce the time it takes to isolate and fix a problem. The following sections discuss the common troubleshooting steps and procedures.

1.	Identify the symptoms and potential causes.
2.	Identify the affected area.
3.	Establish what has changed.
4.	Select the most probable cause.
5.	Implement an action plan and solution including potential effects.
6.	Test the result.
7.	Identify the results and effects of the solution.
8.	Document the solution and process.

Identify the Symptoms and Potential Causes

The first step in the troubleshooting process is to establish exactly what the symptoms of the problem are. This stage of the troubleshooting process is all about information gathering. To get this information, we need a knowledge of the operating system used, good communication skills, and a little patience. It is very important to get as much information as possible about the problem. You can glean information from three key sources: the computer (in the form of logs and error messages), the computer user experiencing the problem, and your own observation.

Once you have identified the symptoms, you can begin to formulate some of the potential causes of those symptoms.

Identifying the Affected Area

Some computer problems are isolated to a single user in a single location; others affect several thousand users spanning multiple locations. Establishing the affected area is an important part of the troubleshooting process, and it will often dictate the strategies you use in resolving the problem.

Problems that affect many users are often connectivity issues that disable access for many users. Such problems can often be isolated to wiring closets, network devices, and server rooms. The troubleshooting process for problems that are isolated to a single user will often begin and end at that user's workstation. The trail might indeed lead you to the wiring closet or server, but that is not likely where the troubleshooting process would begin. Understanding who is affected by a problem can provide you with the first clues about where the problem exists.

Establishing What Has Changed

Whether there is a problem with a workstation's access to a database or an entire network, keep in mind that they were working at some point. Although many claim that the "computer just stopped working," it is unlikely. Far more likely is that there have been changes to the system or the network that caused the problem.

Look for newly installed applications, applied patches or updates, new hardware, a physical move of the computer, or a new username and password. Establishing any recent changes to a system will often lead you in the right direction to isolate and troubleshoot a problem.

Selecting the Most Probable Cause of the Problem

There can be many different causes for a single problem on a network, but with appropriate information gathering, it is possible to eliminate many of them. When looking for a probable cause, it is often best to look at the easiest solution first and then work from there. Even in the most complex of network designs, the easiest solution is often the right one. For instance, if a single user cannot log on to a network, it is best to confirm network settings before replacing the NIC. Remember, though, that at this point, you are only trying to determine the most probable cause, and your first guess might, in fact, be incorrect. It might take a few tries to determine the correct cause of the problem.

Implement an Action Plan and Solution Including Potential Effects

After identifying a cause, but before implementing a solution, you should develop a plan for the solution. This is particularly a concern for server systems in which taking the server offline is a difficult and undesirable prospect. After identifying the cause of a problem on the server, it is absolutely necessary to plan for the solution. The plan must include details around when the server or network should be taken offline and for how long, what support services are in place, and who will be involved in correcting the problem.

Planning is a very important part of the whole troubleshooting process and can involve formal or informal written procedures. Those who do not have experience troubleshooting servers might be wondering about all the formality, but this attention to detail ensures the least amount of network or server downtime and the maximum data availability.

With the plan in place, you should be ready to implement a solution that is, apply the patch, replace the hardware, plug in a cable, or implement some other solution. In an ideal world, your first solution would fix the problem, although unfortunately this is not always the case. If your first solution does not fix the problem, you will need to retrace your steps and start again.

It is important that you attempt only one solution at a time. Trying several solutions at once can make it very unclear which one actually corrected the problem.

Testing the Results

After the corrective change has been made to the server, network, or workstation, it is necessary to test the results never assume. This is when you find out if you were right and the remedy you applied actually worked. Don't forget that first impressions can be deceiving, and a fix that seems to work on first inspection might not actually have corrected the problem.

The testing process is not always as easy as it sounds. If you are testing a connectivity problem, it is not difficult to ascertain whether your solution was successful. However, changes made to an application or to databases you are unfamiliar with are much more difficult to test. It might be necessary to have people who are familiar with the database or application run the tests with you in attendance.

Identify the Results and Effects of the Solution

Sometimes, you will apply a fix that corrects one problem but creates another problem. Many such circumstances are hard to predict but not always. For instance, you might add a new network application, but the application requires more bandwidth than your current network infrastructure can support. The result would be that overall network performance would be compromised.

Everything done to a network can have a ripple effect and negatively affect another area of the network. Actions such as adding clients, replacing hubs, and adding applications can all have unforeseen results. It is very difficult to always know how the changes you make to a network are going to affect the network's functioning. The safest thing to do is assume that the changes you make are going to affect the network in some way and realize that you just have to figure out how. This is when you might need to think outside the box and try to predict possible outcomes.

Documenting the Solution

Although it is often neglected in the troubleshooting process, documentation is as important as any of the other troubleshooting procedures. Documenting a solution involves keeping a record of all the steps taken during the fix not necessarily just the solution.

For the documentation to be of use to other network administrators in the future, it must include several key pieces of information. When documenting a procedure, you should include the following information:

·         Date When was the solution implemented? It is important to know the date because if problems occur after your changes, knowing the date of your fix makes it easier to determine whether your changes caused the problems.

·         Why Although it is obvious when a problem is being fixed why it is being done, a few weeks later, it might become less clear why that solution was needed. Documenting why the fix was made is important because if the same problem appears on another system, you can use this information to reduce time finding the solution.

·         What The successful fix should be detailed, along with information about any changes to the configuration of the system or network that were made to achieve the fix. Additional information should include version numbers for software patches or firmware, as appropriate.

·         Results Many administrators choose to include information on both successes and failures. The documentation of failures might prevent you from going down the same road twice, and the documentation of successful solutions can reduce the time it takes to get a system or network up and running.

·         Who It might be that information is left out of the documentation or someone simply wants to ask a few questions about a solution. In both cases, if the name of the person who made a fix is in the documentation, he or she can easily be tracked down. Of course, this is more of a concern in environments in which there are a number of IT staff or if system repairs are performed by contractors instead of actual company employees.