When should a network performance baseline be measured?
The purpose of a network performance baseline is to record the characteristics of a network during normal operations. This can be used as a standard to determine when a network is performing abnormally. Measurements that are performed during particular circumstances (such as main network device restart or after working hours) will result in an inaccurate set of characteristics for the purpose of a baseline. A DoS attack might cause abnormal network performance, but once it is blocked, network performance should return to normal, so there is no immediate need to measure performance in order to establish a baseline.
An internal corporate server can be accessed by internal PCs, but not by external Internet users that should have access. What could be the issue?
NAT/PAT allows a private IP address to be translated into a public address so that external users can access internal devices. Static NAT assigns one public address to a private address and is used with internal servers.
The newly configured ASBR that connects a company to the Internet has a default route configured and has the default-information originate command entered. Devices connected through this router can access the Internet. The problem is that no other OSPF routers have a default route in the routing table and no other users throughout the organization can access the Internet. What could be the problem?
Because no other routers have a default route, the most likely problem is the link between the ASBR and other OSPF routers, or the advertisement of that link between the ASBR and the other OSPF routers. Cisco routers configured with OSPF automatically accept the common LSAs such as 1, 2, 3, 4, 5, and 7. The ASBR has OSPF configured or the default-information originate command would not have been able to have been entered.
A networked PC is having trouble accessing the Internet, but can print to a local printer and ping other computers in the area. Other computers on the same network are not having any issues. What is the problem?
Since other computers on the same network work properly, the default gateway router has a default route and the link between the workgroup switch and the router works. An incorrectly configured switch port VLAN would not cause these symptoms.
A network administrator is having issues with a newly installed network not appearing in other routers. At which layer of the OSI model is the network administrator going to start the troubleshooting process when using a top-down approach?
Routing is a Layer 3 process. The network layer is another name for Layer 3. The top-down method of troubleshooting typically starts at the application layer, but when a problem is definitely a routing problem, there is no need for troubleshooting to be performed at the higher levels. The problem can only be a Layer 1, 2, or 3 problem.
A network technician is troubleshooting an email connection problem. Which question to the end-user will provide clear information to better define the problem?
To efficiently establish exactly when the user first experienced email problems, an open-ended question should be asked so that the user can state the day and time that the problem was first noticed. Closed questions only require a yes or no answer which will require further questions to determine the actual time of the problem.
Refer to the exhibit. What action occurs at stage 3 of the general troubleshooting process?
There are three stages in the general troubleshooting process:
Isolate the problem
Correct the problem
If the problem is not corrected, the administrator documents the attempted solution, removes any changes made, and returns to gathering symptoms.
Which category of software troubleshooting tools provides device-level monitoring, configuration, and fault-management?
Network management system (NMS) tools include device-level monitoring, configuration, and fault-management tools. Knowledge bases are online repositories of experience-based information. Baselining tools perform tasks of network baselining documentation, network diagram drawings, and network performance statistics establishment. Host-based protocol analyzers capture and decode the various protocol layers in a recorded frame and present the information in a relatively easy to use format.
In which step of gathering symptoms does the network engineer determine if the problem is at the core, distribution, or access layer of the network?
In the “narrow the scope” step of gathering symptoms, a network engineer will determine if the network problem is at the core, distribution, or access layer of the network. Once this step is complete and the layer is identified, the network engineer can determine which pieces of equipment are the most likely cause.
An administrator is troubleshooting an Internet connectivity problem on a router. The output of the show interfaces gigabitethernet 0/0 command reveals higher than normal framing errors on the interface that connects to the Internet. At what layer of the OSI model is the problem likely occurring?
Framing errors are symptoms of problems at the data link layer, Layer 2, of the OSI model.
A network engineer is troubleshooting a network problem and can successfully ping between two devices. However, Telnet between the same two devices does not work. Which OSI layers should the administrator investigate next?
A successful ping indicates that everything is working on the physical, data link, and network layer. All of the other layers should be investigated.
A group of Windows PCs in a new subnet has been added to an Ethernet network. When testing the connectivity, a technician finds that these PCs can access local network resources but not the Internet resources. To troubleshoot the problem, the technician wants to initially confirm the IP address and DNS configurations on the PCs, and also verify connectivity to the local router. Which three Windows CLI commands and utilities will provide the necessary information? (Choose three.)
The ipconfig and nslookup commands will provide initial IP address and DNS configuration information to the technicians and determine if DHCP is assigning correct information to the PCs. The ping utility would be used to verify, or not, connectivity to the default gateway (router) using the configured default gateway address, or using the known correct default gateway address if these are found to be different. The arp -a or netsh interface ipv6 show neighbor commands could be used if the problem is then suspected to be an IP address to MAC address mapping issue. The telnet and tracert utilities could be used to determine where the problem was located in the network if the default gateway configuration was found to be correct.
Open the PT Activity. Perform the tasks in the activity instructions and then answer the question.
A user reports that PC0 cannot visit the web server www.server.com. Troubleshoot the network configuration to identify the problem.
What is the cause of the problem?
The status of interface S0/0/0 is up but the line protocol is down. A possible problem could be a framing error or an encapsulation error.
A user in a large office calls technical support to complain that a PC has suddenly lost connectivity to the network. The technician asks the caller to talk to nearby users to see if other machines are affected. The caller reports that several immediate neighbors in the same department have a similar problem and that they cannot ping each other. Those who are seated in other departments have connectivity. What should the technician check as the first step in troubleshooting the issue?
A user reports that after an OS patch of the networking subsystem has been applied to a workstation, it performs very slowly when connecting to network resources. A network technician tests the link with a cable analyzer and notices that the workstation sends an excessive number of frames smaller than 64 bytes and also other meaningless frames. What is the possible cause of the problem?
The symptom of excessive runt packets and jabber is typically a Layer 1 issue, such as caused by a corrupted NIC driver, which could be the result of a software error during the NIC driver upgrade process. Cable faults would cause intermittent connections, but in this case, the network is not touched and the cable analyzer has detected frame problems, not signal problems. Ethernet signal attenuation is caused by an extended or long cable, but in this case, the cable has not been changed. A NIC driver is part of the operating system, it is not an application.
Which troubleshooting method begins by examining cable connections and wiring issues?
In troubleshooting with the bottom-up method, a technician would start with the physical components of the network and move up through the layers of the OSI model until the cause of the problem is identified.
Fill in the blank.
Use the __ cache to verify IPv4 address to Layer 2 Ethernet address mappings on a host computer.
The ARP cache is used to store IPv4 addresses and the Ethernet physical addresses or MAC addresses to which the IPv4 addresses are mapped. Incorrect mappings of IP addresses to MAC addresses can result in loss of end-to-end connectivity.
Which three pieces of information are typically recorded in a logical topology diagram? (Choose three.)
There are two types of network topology diagrams: physical topology diagrams and logical topology diagrams. Logical topology diagrams show how devices are logically connected and how data moves through the network. Logical topology diagrams include information such as IP addresses, routing protocols, and static routes.
After which step in the network troubleshooting process would one of the layered troubleshooting methods be used?
A layered troubleshooting approach (top-down, bottom-up, or divide-and-conquer) is used to gather hardware and software symptoms from the suspect devices.
A team of engineers has identified a solution to a significant network problem. The proposed solution is likely to affect critical network infrastructure components. What should the team follow while implementing the solution to avoid interfering with other processes and infrastructure?
Change-control procedures should be established and applied for each stage to ensure a consistent approach to implementing the solutions, and to enable changes to be rolled back if they cause other unforeseen problems.
Users report that the new web site http://www.company1.biz cannot be accessed. The helpdesk technician checks and verifies that the web site can be accessed with http://www.company1.biz:90. Which layer in the TCP/IP model is involved in troubleshooting this issue?
The issue is that the new web site is configured with TCP port 90 for HTTP, which is different from the normal TCP port 80. Therefore, this is a transport layer issue.
A company is setting up a web site with SSL technology to protect the authentication credentials required to access the web site. A network engineer needs to verify that the setup is correct and that the authentication is indeed encrypted. Which tool should be used?
To verify that the authentication is indeed encrypted, the authentication process needs to be captured and investigated, which can be accomplished through a protocol analyzer, such as Wireshark. A baselining tool is used for automating the network documentation and baselining process. A fault-management tool is used to manage the fault tolerance of network devices . A cable analyzer is used to test and certify copper and fiber cables for different services and standards.
What is a purpose of establishing a network baseline?
A baseline is used to establish normal network or system performance. It can be used to compare with future network or system performances in order to detect abnormal situations.
Refer to the exhibit. On the basis of the information presented, which two IP SLA related statements are true? (Choose two.)
From the output, the IP SLA is configured to perform icmp-echo, the target device is 192.168.2.1, and the icmp-echo requests are sent every 10 seconds. "Start Time already passed” indicates that the operation has started. The "Life" parameter indicates that the setting is "Forever".
Which two specialized troubleshooting tools can monitor the amount of traffic that passes through a switch? (Choose two.)
Network analysis modules and portable network analyzers such as the Fluke OptiView can monitor network traffic to investigate the amount of data going through switch ports. TDRs, DMMs, and DTX cable analyzers are used to investigate physical media errors and lengths.
Which number represents the most severe level of syslog logging?
Syslog levels are numbered 0 through 7, with 0 being the most severe and 7 being the least severe.