Network Troubleshooting Symptoms And Solutions

web Troubleshooting Symptoms And SolutionsData transfer from wiz rase to a nonher is the most most-valu competent aspect of figurers. Networks should be safe, reliable and unafraid for tuition movement. Any business which occurs with calculating machine interlockings political campaigns havoc. Understanding profitss, the way they work, and how they argon built seconds a net executive to identify and particularise the troubles.11.2 procedure to troubleshoot lucre capersA simple formula that enables electronic net profit executive directors reckon from each one kind of interlocking trouble is de huntate the symptoms. let on the affected bea. catch what has changedSelect the most probable ca practice use a responseTest the resultRecognise the potential do of the tooth root text file the solution11,2,1 Identify SymptomsIndicators ar either personal or luculent symptoms that help determine the nature of the job, the reach of the trouble, etc. These symp toms enable a interlock executive to take clockly pr itemive measures to mould the enigma before it grows beyond control.System or operator line of worksSystem mistakes line up from a computer, profits device or a process that is non related to a drug substance abusers direct interaction with the organisation or meshwork. such phantasms drop occur due to hardwargon failure, faults in the process of data transfer or manipulation.Operator errors argon a direct subject of a users action. The actions that pot produce such errors may be wrong(p) log in, wrong bondions to a server, misidentification of servers or mesh devices, incomplete meshing connections, etc. Mistakes on part of the mesh come ab show upology executive that be parking area causes of operator errors are misconfiguration of devices, programs or operate.Link clear(p)sWhen a interneting device detects a earnings connection a green or amber Light-Emitting junction rectifier (LED) is turne d ON. This is the link luminosity that shines when in the ON state. Comp hotshotnts of a meshing are designed with link lights to show the state of the earnings connection. When a physiological profits connection is cave in a link light remains on and an early(a) light is present that displays the current practise of the entanglement card and blinks, pluses, during data transfer.. Link lights are designed to non light up in field of an incorrect web subscriber line connection. By examining the link light of a device, a user tramp determine if a interlocking connection is ladder or non. conflict lightsLights that indicate whether a certain(prenominal) connection is confront problems due to packets colliding with one a nonher is a smasher light. The collision light (activity light) is green turn s subverting and receiving data and is yellow or orange when a collision error is detected. The packet cosmos received or sent is mazed when a collision occurs. Faulty courses or hubs shadower result in packets being generated from other packets or electrical interfaces which when in sizable order of magnitude are c all(prenominal)ed chatter. These network chatters can end up halting an complete network because of data packet collision. Network executives and users should monitor these lights to detect network chatter and avoid it.Power lightsA power light indicates if thither is power supplying to the networking device or non. In case in that respect is no power supply the power light is off. The power supply cables or wall connectors should be matched for right(a) connections while troubleshooting a network problem. defect displaysA device failure or give reveal is indicated by an error display. A visual error dialogue knock on the computer or an LED error display on the network device is the form of an error display. These displays also describe the problem that is detected. Typically, an error display relates to an error code that should be referred by the user to identify the cause and a suitable solution. Every physical or lucid problem has a unique solution provided by its producer which can be found in its reinforcement. hallucination logs and displaysA hark of the errors encountered on a network device is the error log. The time of the error occurrence, the nature of the error and a suitable solution is what constitutes an error log. The information found in an error log is non sufficient to solve a problem and over come acrosss the sup port wine of the related documentation to resolve the problem.Error logs are important sources of information that includes the time of the error, probable cause and other processes affected by the error. An error display gives a visual officious of a problem and logs it in the error log. Not all error displays look at speedy attention barely a few are warnings that do non indicate an living error but indispensableness attention.An Event Viewer is an error l ogging mechanism which is typical to Windows-based OS such as Windows clients and servers. Event viewer is a critical brute in diagnosing and re settlement a problem. Red-X error entries that have occurred are recorded in an flatt viewer. This is an application that reads the binary log files stored at placement32config folder.To view the error logs, the network administrator requires to view the config folder because the event viewer collects information from the files located in that folder.Error logs are of triple showcases which should be monitored by the network administrator regularly and they are as follows.System log Error substances that are related to device device driver failure, service start failure and general information about OS events are recorded in the clay log.Security log When auditing has been enabled all protective cover related events are recorded in a security log.Application log Events that are generated by application running on top of the OS a re recorded in an application log.Identify network problemsTroubleshooting a network is one of the key concept in networking. Identifying network problems and determine methods of troubleshooting these problems is vitally important for unruffled surgical operation of a network.The job of highlighting the problem is usually done by the network user. This should not be the basis on which an administrator should attack a problem. It is advisable to experience the problem in person a keen-sighted with the user who reported it. This helps the network administrator confirm if the problem is real or just an error. There are certain users whose knowledge about computers and networks is not vast. With such users when a problem is reported, a first-hand inspection and confirmation are necessary.The vanquish approach to solving a problem is by determining its setting. The reason why an understanding of the nature of the problem is essential is that it determines the line of attack.Gatherin g information helps the network administrator to narrow down to the idea of the problem. This approach avoids a network administrator spending unnecessary time on unnecessary jobs. After the network administrator is able to locate the cause of the problem, because perplexing a solution is possible.A network administrator must first gather information to find out if the problem is with a single computer or with the wide-cut network. In case the problem is local anesthetic, thus the inbuilt network is not make fulled down(p) and a solution can be found easily. The first logical step that is to be taken is to go through all cable connections to and from the system. It is not advisable to look into bigger final payments or tar write down larger sources when the cause cogency be very simple. The reason why a system is not able to connect to other systems may be that the network cable is not plugged in properly into the system. When the cable is attached properly, the netwo rk connection is up and running.For example, if two systems in a network are not able to communicate with each other then the network administrator can perform simple checks like validatory the connections between the systems or connections to the networkA network administrator should check if a problem is consistent and replicable. If the problem reported unique to a system or can it be replicated in other systems in the network. If the same problem is reported from another system also, then the problem is consistent and replicable. The class of impairment is high in such a case since many systems are affected. If the problem is determine to be with the network, then the network administrator must reach to the cause of the problem step-by-step.A large computer network requires a lot of effort from the network administrators and users for it to run smoothly. Adding to the huge task of maintenance is the job of nonpl use a problem. It becomes nasty to identify the actual probl em for there are legion(predicate) workgroups and workstations. It is advisable to approach large network problems with the trial and error method.The administrator should first check the local system from where a problem has been reported. A thorough check of its cable connections, network links, power supplies and so on should be done. If the problem is not with a local system then other systems in the vicinity should be checked. The routers to and from the system should be substantiate for proper functioning. The various connections should be verified.One of the best methods to check and fix network problems is to tense connecting to other systems and separate of the network by pinging to them.11.2.2 Identify the affected area.After the cause of the problem is identified it is simple logic to set apart the affected area. This step helps an administrator narrow down to the outcome of the problem. With many turn outs to be handled at a time administrators must order the prob lems. Issues which affect work to a large extent should be better first and the rest should follow sequentially. By doing this the downtime can be minify and the system can be dogged faster.Same line, different computerWhile trying to solve a problem it is important to isolate the affected system. A simple method of testing if the problem is replicable is by replacing the original workstation with another system which is known to have no problems. By validating if the problem is with the local system or beyond it, the network administrator eliminates one factor of the problem. An easy way of discriminate the system is by replacing it with another system. This step determines if a problem is computer specific or not.Same computer, different lineWhen a user reports of a problem, another method by which the administrator can reach the cause of the problem is by changing the network cables for the system. By doing this, the possibility of a network error can be identified or nullif ied. In case the system works properly with a sensitive connection, then it is for sure that the problem is with the original network and not the computer.Swapping componentsIn a network, hubs, cables, terminators can be swapped with other systems to check for regaining or consistency of a problem. This helps in case there is a faulty component and the work of the original system user is not disturbed since a spare is in place. This step helps determine the scope of the problem and address it appropriately.Prioritising work is very important for network administrators and network administrators since the time and effort used to fix a problem should help users to get sustainwards to work faster. Bigger and of the essence(p) problems require immediate action while the smaller ones can be addressed later onwards the bigger ones are fixed.Isolating segments of the networkBy isolating move of the network spread of the problem is checked such that the entire network does not colla pse. The systems which have reported breaks are necessitate to be disconnected from the network and terminators plugged in. This is a safe practice as it helps the network administrators fix the problem with lesser clog ups of data and work.Steps for problem closing off are given in set back 11.1StepAction look which systems are and which are not covering symptoms.Separate the systems that are showing symptoms from those that are not with hubs or terminators.Rule out simple issues. define all major connections to and from the system.Eliminate cable problems. diaphragm for physical price or erroneous connections of cables.Eliminate serious cable issues.Use TDR to find out cable problems.Table 11.1 Methods to isolate network problems.11.2.3 Determine what has changed calculator networks have many components, both hardware and computer software that can be deputised or reset to meet the requirements of the business. This can also be one of the causes of a network problem.For e xample, if a user reports of a problem after a system in a network is replaced then the administrator should check if the address of the changed system is properly recorded and connected with the active network.To be able to fix problems when changes are made to the network, it is advisable to suffer proper records of all details about the new and existing network such as the patchs of change, the components of change, their versions, IP addresses and network cables. A detailed documentation system helps fix such issues quickly.Checking the status of serversServers are an integral and crucial election in a network. Their health is very important for functioning of a network. Therefore it is logical to check the server status when go about with a problem. If sever issues are not addresses on time, then the degree of damage can be high.A few server monitor tasks that can monitor their status are as followsCheck servicesCheck error logsCheck connectivityMonitor mathematical proce ss and network dutyConfirm alerts and alarmsVerify ministration logs along with test restores.Checking error logsError logs are an important source of information for a network administrator. It throws light on the errors that have occurred and their nature. The amount of damage can also be assessed from this log. The administrator can prioritise errors on the extent of damage and fix them in that order. It is important to review the error log on a daily basis because certain errors have dependencies which can spread the damage faster. It is advisable to make it a habit to check the error logs at some point of time in the day to help the network work better. Connectivity between systems or servers can be tested using the Ping feature. If the system at the other end of the ping message responds then the connection is intact, else a thorough check of the connection should be done. Regular checks should be carried out to look out for server overload problems. An overloaded server can slow down system performance and speed. Backup servers should also be monitored for updates and performance. In the event of an emergency business data and resources are very crucial. An alert system can be designed which can raise alarms when predefined limits are exceeded. This is a heavy enlistment measure that helps in proper functioning of a network.Checking for configuration problems onward introducing a new resource into the network it is necessary to verify the existing configurations and connections. In case the existing settings are incorrect, then the new resource cannot work.For example, before setting up a new server it is dependable to check the base OS, TCP/IP, network cables, error logs and memory allocation for accuracy. This improves performance and does not allow deterioration of the system.After the existing settings and connections are verified the new resource and additional services must be configured accurately. There are a few tasks which require the en tire network to be turned off for a few proceedings before rebooting. This activity has to be timed for low work load hours.A few critical services which determine functioning of the entire network and requries constant monitor and accurate configuration areDNSa Microsoft active directory and other meshing-based applications supports this service. A detailed plan should be in place before configuring a DNS which require a list of information before installation.Domain nameWINSWINS is a feature similar to DNS which resolves NetBIOS call to IP addresses. This is a dynamic service which can add, modify and take name registrations and avoid human errors and save time. WINS has many configuration possibilities and the user can add a static mapping for clients or severs. multitude fileHost files and DNS are similar in function. Host files require manual configuration of database with exact mappings of soldieryname to IP addresses. Host files reside on every computer making the proces s of updating difficult. It is very important to provide correct hostname to IP address mappings so that all rules that hand to the DNS, also apply to the host files. To avoid typing errors while configuring host files, it is safe to copy the existing hosts to the newly created file and on each of the machines.Checking for virusesViruses are a huge and putting surface threat to computers. A computer network is at greater risk as the number of computers is large and the damage can be huge. Protecting networks and computers outside of networks from viruses is a top priority job. Viruses grow in the computer world at a pace which matches the growth in the biological world. The mechanisms to destroy viruses evolve every minute to fight the strongest and newest virus. It is the job of the network administrator to keep the network free of viruses. Constant updates of virus definition files, scans to check for entry of viruses and antivirus software are the most popular and best methods to fight them. Preventive measures are best when deployed round the clock. All resources in a network should be scanned for viruses and guarded from them. Every piece of software and hardware is crucial to the smooth working of a network or system. There are a number of virus scanning utilities available in the market which enables computers to mechanically update virus definition files from a core server hence avoiding the administrator making trips to each workstation.Checking the validity of composition name and discussionAccount name and password are the gates that cut the user to a unharmed world of services, applications and data. Their validity matters a lot for the user to be able to access services, applications or data. Many services use the built-in system placard details for success while a few other services require the user to log on to a irrelevant system. This task requires an account name and password that resides in the network account database. To activate certain services or applications, administrative privileges or membership in certain groups is necessary which again requires account name and password. For quite a few system-related tasks, administrative rights are required which allows the user to modify certain settings to suit the need. The worst situation is when a network administrator has configured many applications and services with the administrator account which gets deleted on end of service of the administrator. If all services and applications using the administrator account are disabled and access is denied, then it is very difficult to fix this.Rechecking operator logon proceduresVery often users end up facing problems with passwords. Users try to logon to a part of the network for which access is not granted, stop passwords, do not remember the case-sensitive feature of passwords, and so on. Many a times a user tries more than thrice to logon with a certain or different passwords after which the user is locked out . To resolve this minor but deep-penetrating issue the administrator must reset the password for the user. Passwords should be changed at regular intervals for safety and to avoid expiry and this is an issue for many users.Selecting and running appropriate symptomaticsDiagnostics is an essential tool to even out variations and eradicate potential problems in a network. Though this is a preventive mechanism the benefits of using it are many. Diagnostics look out for bottlenecks and toughened situations. Diagnostic tools bring out problems or drawbacks and limitations that can be fixed before they erupt as big problems. While choosing a diagnostic program the user should bear in mind the network requirements for which it is to be employed. Smaller networks should use simple diagnostic programs while large networks require extensive protocol analysing and packet sniffing products. Free diagnostic products such as performance monitor and network monitor work well for a medium sized ne twork. To utilise the tool to the maximum without affecting the network performance, the network administrator must research the diagnostic product in depth. With experience and products like these, an administrator is able to identify the problem in time and resolve it effectively. A reliable baseline of activities must be established for testing. Snapshots of different activities at different time periods of the day, week and month helps assess the network efficiently and accurately.11.2.4 Select the most probable causeOf the many steps suggested to solve a problem, experience of the network administrator is a capability that matters a lot for the process. In case the network administrator is not well versed with the network or common network issues, resolving becomes a tough task. The way a network administrator approaches a problem solves the issue to quite an extent for it can guide or misguide the way the solution is built. In case a new or an outside network administrator is being roped in to solve a network problem the chances of long system downtime is high. The new network administrator has to get familiarised with the network, and then look out for probable causes. The more the experienced the network administrator is, the easier it is to solve the problem.Many a times problems may be similar across systems and a network administrator can tap the experience from the one-time(prenominal) to fix it faster. A company can benefit largely from a full-time network administrator and who knows the details of the network at the back of the mind.Common problems and their probable causesThe common network problems are their probable causes are given in Table 11.2ProblemProbable causeCannot connect to a computer on a remote network.A routing issue in all probability. Check if it is possible to connect to a local system and ping the router or another system on the remote network.Communication in the entire network is down.If in a coax-based network, check for loose connections. If in a twisted-pair network, check if the hub is operational. If in a item ring network, check if the computer is not beaconing.Takes a very long time to connect to a network resource.Network may be overloaded.A device on the system is not functioning and network connection is not possible.A network card configuration issue in most cases. Check if the NIC is configured properly. Driver may be loaded incorrectly.Communication in a local network is not possible, but other networks are working.Check if the hub/switch is not locked up. Check if the network adapter is configured properly.No meshwork access.Check the Internet gateway. Check the router present has a dedicated Internet connection. Check the Internet providers network.Token ring network is locked up.Someone in the network is beaconing. also check if the bridge is locking up.Table 11.2 Certain problems and probable causes11.2.5 Implement a solutionIn order to fix a problem a network administrator can con sult others, read related documents, research from the Internet and seek help from the vendor help lines. eventually with a solution on hand that seems most suitable it should be implemented without any delay.11.2.6 Test the resultConfirming if the solution implemented is correct and has understand the problem is very crucial to the problem solving process. Any user contacts the network administrator with a hope of haunt the problem and getting back to work. If the network administrator leaves the user without confirming if the solution provided is correct, then the purpose of the network administrator being present is defeated. It is the duty of the network administrator to ensure that the problem with which the user had approached does not repeat.11.2.7 Recognise the potential effects of the solutionWith a working solution in place the next factor that a network administrator should consider is the aftermath of the solution. Many instances can be found where a certain solution to a problem has triggered problems in other parts of the system or network. This cascading effect of a solution requires to be monitored and checked. For example, a user may report a system dialogue problem and a solution can be provided by resetting of the network cables. The local problem of the system not being able to communicate office be solved, but the system expertness still not be able to connect to some other parts of the network. Such ripple effects of a solution require attention from the network administrator. prissy implementation of a solution, confirming its working and nullifying all side effects of a solution completes the solution phase.11.2.8 Documenting the solutionAfter a problem reported has been solved and work is back to normal, it is the job of the network administrator who solved it to document it properly for future use. The fact that certain problems might recur after some period of time, a new network administrator might face a problem already solv ed earlier, and so on are the reasons why documentation is necessary. An organisation benefits from proper documentation of troubleshooting when there is a change of hands with network administrators, speech on time by not going through the whole process after an apt solution is found by one. It even benefits when a certain solution has faded in the memory of a network administrator. Proper documentation for each aspect of troubleshooting is as good as providing an appropriate solution on time.11.3 Common connectivity issues in a networkThe common connectivity issues in a network can be of two types network failure due to physical problems such as device or cable issues and logical problems such as disable IP addresses or VLAN problems.11.3.1 Physical issuesCabling problems are the most common physical issues. Visual indicators such as link lights, activity lights and collision lights can be used to fix these problems. A few common problems that a network administrator fixes areR ecognising abnormal physical conditionsTo be able to recognise deviations from the normal, a good knowledge of what is the normal is essential. If the user is not aware of the default information, then it is not possible to alter or reset details. A user should be aware of certain issues in order to spot a problem. These issues are as follow stylemark takes more time.More errors are logged than usual.Printing is taking more time.Connecting to a network is getting slower.Connections to resources are being lost.Isolating and correcting problems in the physical mediaNetwork cables are the most vulnerable resources in a network. They end up leading to a whole range of problems and can get fixed easily. The cable which is at a high risk of problems is the cable from the workstation to the wall jack.A solution as simple as plugging it back can solve network problems at times.If the problem is not solved, try another cable and try with other cables till contact is established. phone line p roblemProbable solutionCommunication in the entire network is down.Check if the cable is intact. The point at which the cable has been damaged should be reconnected with a new cable.The new UTP cable is not enabling network communication. The network is working with the test cable.The new UTP cable might be a crossover cable. Test the connections with a cable tester and replace the UTP cable if not fine.A system was moved to a new location and is not able to communicate now. The system is working properly.Cables might be damaged during transit. Replace the old cables with new ones for proper connection.Table 11.3 Common cable problems and probable solutions.CrosstalkWhen adjacent wires deputize with a certain wire system it is called crosstalk. The first indication of crosstalk is level degradation. Using another cable type with multiple layers of shielding is the best solution for this problem.Nearing cross talkIssues in network connectivity occur when a cable wire causes electro magnetic interference in the wires adjacent to it and releases a current. This point has the strongest possibility of cross talk and is generally present in the first part of the wire which is connected to a connector, switch or NIC. Nearing crosstalk helps to measure this type of cross talk.AttenuationSignals degrade as the distance they travel increases, this is called attenuation. If a user finds it difficult to communicate with system at quite a distance, then the maximum cable aloofness for that type of cable would have exceeded. In such a case, a repeater can be used at some point in the cable to reamplify signals or a different cable type can be used.CollisionsData collision is a common issue when there are many systems in a network. Data packets change of location across the network collide with each other affecting network performance. To resolve this issue network hubs can be replaced with switches which has each port on the switch owning its own network segment ensuring that data does not collide.ShortsA network short leads to network downtime. Using a cable analyser to identify shorts can reduce the problem of connectivity and shorts.Open impedance mismatch (echo)Network signals bounce causing communication problems due to high impedance. Signals bounce because of miswired cables or incorrect connectors. Recrimping of the cable is a good solution to avoid high impedance problems.InterferenceNetwork cables experience signal interference from external components like power cables, backup lines, etc. Network cables should be laid away from agents that can interfere with its signals.11.3.2 Logical issuesLogical issues have simple solutions but can lead to huge problems if not addressed properly. A few logical issues and solutions are listed in this section.Port speed and duplex settingsConfirming that the speed and duplex settings of the network card are set correctly avoids problems for systems connecting to each other across a network. awry(p) VLA NCommunication between systems across VLANs is not possible unless there is routing done between them. Therefore placing systems corresponding to the VLAN is important.Incorrect IP addressIf IP addresses of systems a