Network troubleshooting (net+ 007 )
Ralph has been advised to check his Linux web servers for open ports that attackers might be able to use to penetrate the servers' security. Which of the following utilities can Ralph use to do this?
nmap. The nmap utility is capable of scanning a system for open ports that might be a security hazard. The tcpdump, dig, and iptables utilities cannot do this.
Which of the following route commands displays the contents of a Windows computer's IPv6 routing table only?
route print -6 The route print command displays both the IPv4 and IPv6 routing tables. To display only the IPv6 routing table, you add the -6 parameter to the route print command. route list and route list -6 are not valid commands.
Which of the following are NOT tools that run only on Unix or Linux systems?
route. Of the utilities listed, tcpdump, dig, iptables, and ifconfig are all tools that run on Unix/Linux systems only. The route utility runs on both Unix/Linux and Windows.
Which of the following protocols does the ping program never use to carry its messages?
TCP. All Windows ping transactions use ICMP messages. ICMP messages are encapsulated directly within IP datagrams; they do not use transport layer protocols, such as UDP. ping transactions to destinations on the local network are encapsulated within Ethernet frames. On Unix and Linux, ping uses UDP, which is also encapsulated in IP datagrams.
Ralph has begun to receive calls from users reporting that they cannot access the local network or the Internet. Ralph checks their computers and discovers that all of the users with a problem have IP addresses in the 169.254.0.0/16 network, which is not the address used on Ralph's network. Which of the following might be the cause of the problem?
THe Ip address leases aassigned by the DHCP server have expired The 169.254.0.0/16 network is used by Automatic Private IP Addressing (APIPA), a standard that provides DHCP clients with an IP address when they cannot contact a DHCP server. Unknown to Ralph, the DHCP server on his network has been down for over a week, and the users' IP address leases have begun to expire. This causes them to revert to APIPA addresses. Multiple users changing their IP addresses would not result in them all using the same network address. A rogue DHCP would not be likely to deploy APIPA addresses to clients. Malware infections that modify IP addresses are rare.
Which of the following statements about cable certifiers are true? (Choose all correct answers.)
(1) A cable certifier eleminates the need for tools like tone generators and wiremaps (2) Cable certifiers must be reconfigured when a new cable specification is standardized . Cable certifiers can detect all of the faults that tone generators and wiremap testers can detect, and they can do a great deal more, such as specify whether a cable run meets the performance specifications defined in a cable standard. When testing a new cable type, the specifications defined in the cable standard must be added to the device. Cable certifies are far more expensive than most other cable testing solution. Cable certifiers are available that support various cable media, including copper and fiber optic.
Which of the following tools might you use to connect internal twisted pair cable runs to the keystone connectors that snap into wall plates? (Choose all correct answers.)
(1) A punchdown tool (2) A wire stripper The punchdown tool is critical to this operation. In one motion, the tool strips the insulation off of the wire, presses it down into the connector, and cuts off the excess at the end. A wire stripper simplifies the task of preparing the cable for the connection process. A crimper is used only for attaching connectors to patch cables, and pigtail splices are used only on fiber-optic networks.
Ralph is having trouble providing satisfactory wireless network performance to a row of glass-walled conference rooms at the far end of the building. The doors to the conference rooms are also made of glass and are always closed when meetings are in progress. Which of the following types of radio signal interference are likely to be the main issues that Ralph is trying to overcome? (Choose all correct answers.)
(1) Attenuation (2) Refraction . Attenuation is the tendency of signals to weaken as they travel through a network medium. In the case of a wireless network, the medium is the air, and the farther away a wireless device is from the access point, the weaker the signal will be. Refraction is when signals bend as they pass through certain types of barriers, such as the glass walls of conference rooms. The bending changes the direction of the signals, possibly causing them to weaken in the process. Reflection is when signals bounce off of certain surfaces, such as metal. Diffraction is when signals have to pass around barriers to reach a particular destination. All of these phenomena can weaken the radio signals used in wireless networking, but attenuation and refraction are likely to be the primary problems for Ralph in this case.
Ed is trying to troubleshoot a problem that has caused a wired network connection to slow down noticeably. Which of the following wired network problems will cause a drastic slowdown of a network connection, without causing it to fail completely? (Choose all correct answers.)
(1) Bottleneck (2) Duplex mismatch. A bottleneck is a component involved in a network connection that is not functioning correctly, causing a traffic slowdown that affects the entire network. A duplex mismatch occurs when one side of a connection is configured to use full duplex and the other end is configured to use half duplex. When this occurs, the full-duplex communications on the one side look like collisions to the half-duplex side. The half-duplex adapter transmits a jam signal as a result of each collision, which causes the full-duplex side to receive an incomplete frame. Both sides then start to retransmit frames in a continuing cycle, causing network performance to diminish drastically. A speed mismatch or a TX/RX reversal will stop network communication completel
Ed is implementing a web server farm on his company's network and has installed a router to create a perimeter network on which the web servers will be located. However, Ed now cannot access the web servers from his workstation on the internal network. Which of the following tasks will Ed have to complete before he can access the perimeter network from the internal network? (Choose all correct answers.)
(1) Change IP addresses (2) Change default gateway addresses (3) Update the DNS records. Ed will first have to change IP addresses. This is because the computers on the other side of the router, on the perimeter network, must use an IP network address that is different from the internal network's address. Next, Ed will have to change the default gateway address setting on the internal network computers to the address of the router so that traffic can be directed to the perimeter network. Finally, Ed will have to update the resource records on the DNS server to reflect the IP address changes. MAC addresses are hard-coded into network interface adapters and are not easily changed.
Ralph is adding new workstations to his wireless network, which uses an access point that is configured to use WPA2 encryption. However, after installing the wireless network adapter on the first workstation, Ralph finds that he cannot see the wireless access point on the Available Networks display. Which of the following could be the problem? (Choose all correct answers.)
(1) Channel overlap (2) Incorrect antenna placement. Both interference resulting from channel overlap and incorrect antenna placement could render the workstation unable to make contact with the access point. An incorrect passphrase would not be the problem unless Ralph had already seen the access point and attempted to connect to it. An incorrect SSID would be the problem only if Ralph had already attempted to manually enter an SSID
Alice receives a call from a user who cannot connect to the company's 802.11g wireless network with a new laptop that has an 802.11ac network adapter. Other users working in the same area are able to connect to the network without difficulty. Which of the following steps can Alice perform to resolve the problem? (Choose all correct answers.)
(1) Install an 802.11ac wireless access point on the network (2) Install an 802.11g wireless network adapter in the user's laptop. The 802.11ac and 802.11g wireless networking standards are fundamentally incompatible. The 802.11g access point uses the 2.4 GHz band and the user's 802.11ac laptop uses the 5 GHz band. Therefore, the only possible solutions are to install an 802.11ac access point or an 802.11g network adapter. Changing channels on the access point and moving the user will have no effect on the problem.
Several accounting consultants are working in Ed's office for the first time, and they are unable to connect to the 802.11n wireless network with their laptops. Which of the following tasks should Ed perform first to try to resolve the problem?
(1) Make sure that the consultants are attempting to connect to the correct SSID (2) Make sure that the consultants laptops are configured to use the correct wireless security protocol . Of the options provided, the ones most likely to be causing the problem are the use of an incorrect SSID or security protocol. Although signal interference could possibly be a cause, it is more likely that the new users have devices that are incorrectly configured for Ed's network. Channel overlap is a problem that Ed would check and resolve at the access point, not the users' workstations.
Which of the following statements about prioritizing help calls are true? (Choose all correct answers.)
(1) Problems with shared resources take prescedence over individual desktop problems (2) Network-wide problems take precedence over departmental problems. When establishing priorities, network-wide problems take precedence over departmental problems, and problems with shared resources take precedence over individual desktop problems.
Ed is trying to troubleshoot a problem that has caused a wired network connection to fail completely. Which of the following wired network problems will cause a complete failure of a network connection? (Choose all correct answers.)
(1) Speed Mismatch (2) Tx/Rx reversal. A speed mismatch on a wired network only occurs when two devices are configured to use a specific transmission speed and those speeds are different. In that case, network communication stops. For network communication to occur on a twisted pair network, transmit (TX) pins must be connected to receive (RX) pins. If the connections are reversed, no communication occurs. Bottlenecks and duplex mismatches will slow down network communications, but they will not stop them dead.
Ed is trying to troubleshoot a problem with his wired network, and his research has led him to a list of possible network faults. The list is rather old, however, and Ed is wondering if some of the problems are relevant. Which of the following wired network problems no longer occur with modern Gigabit Ethernet switches and network adapters in their default configurations? (Choose all correct answers.)
(1) Speed mismatch (2) Bottleneck . The Gigabit Ethernet standards call for switches and network adapters to support autonegotiation by default, which enables devices to communicate and select the best network speed and duplex mode available to them both. Therefore, speed mismatches and duplex mismatches no longer occur unless someone modifies the speed or duplex settings to incompatible values on one or both devices.
Ralph is setting up a workstation for the company's new vice president. He has installed the computer in the VP's office and plugged it into the wall plate. Then, back in the datacenter, he uses a patch cable to connect the corresponding port in the patch panel to a port in the network switch. However, the computer is unable to access the network. There are no complaints from other users. Which of the following could be the source of the problem? (Choose all correct answers.)
(1) The switch port is disabled (2) The switch is configured to use port security It is common practice on many networks to disable switch ports that are not in use so that unauthorized individuals can't plug devices into them. Some networks also use port security, in which switches are configured with access control lists (ACLs) that specify the MAC addresses of devices that are permitted to use them. Either of these could be the source of Ralph's problem. Because there are no other network users reporting problems, malfunctioning services such as NAT and DNS are not likely to be the cause.
Ralph's company has expanded to include an additional building on the far end of the corporate campus, approximately four kilometers away from the building housing the datacenter. A single-mode fiber-optic cable connection has been installed between the new building and the datacenter for a 1000Base-BX10 connection, but the cable is not yet connected to a transceiver at the datacenter end. Noticing that there is a 1000Base-SX transceiver module in the datacenter store room, Ralph is wondering if he could use this on the new cable run. Which of the following are reasons why this might not work? (Choose all correct answers.)
(1) Transceiver mismatch (2) Incorrect cable type (3) Excessive cable length (4) Wavelength mismatch. The 1000Base-SX standard calls for multimode cable with a maximum length of approximately 500 meters, while the new cable run is 4,000 meters and uses single-mode cable. The 1000Base-SX transceiver will also be incompatible with the 1000Base-BX10 transceiver at the other end. 1000Base-BX10 uses wavelengths from 1,300 to 1,600 nanometers, whereas 1000Base-SX uses wavelengths of 770 to 860 nm.
Trixie has recently moved to a new office in her company's building, down the hall from her old one. Since the move, she has only been able to access the wireless network with her laptop intermittently. She never had a problem in her previous location. Which of the following could possibly be the cause of her problem? (Choose all correct answers.)
(1) Trixie's new office is farther from the access point than her old one. (2) There are too many walls between Trixie's new office and the access point.
On Monday morning, Alice arrives at work to find multiple email and telephone messages from users who are unable to access the Accounting department's file server. Which of the following are the best questions to ask during the beginning stage of the troubleshooting process? (Choose two.)
(1) What has changed since the users were last able to acces the server (2) Which users are reporting a proble and where are they located . The first stage of the troubleshooting process calls for Alice to identify the problem by gathering information. Learning about who is reporting the problem and what has changed since the server was last accessible can provide Alice with information that could help her determine whether the problem is located in the users' workstations, somewhere in the network, or in the server itself. The other options are intended to test a theory about a probable cause, a troubleshooting stage that comes later.
Which of the following utilities can you use to view resource record information on a particular DNS server? (Choose all correct answers.)
(1) dig (2) nslookup nslookup and dig are both command-line utilities that you can direct to a specific DNS server and then generate queries that display resource record information the program retrieves from the server. netstat displays information about networking protocols, whereas nbtstat displays information derived from the system's NetBIOS over TCP/IP implementation. arp is a tool that you can use to display and manage a system's ARP table entries. netstat, nbtstat, and arp are not able to display resource record information.
Which of the following command-line utilities can run on both Windows and Unix/Linux systems? (Choose all correct answers.)
(1) ping (2) nslookup The ping and nslookup utilities can both run on Windows or Unix/Linux systems. The traceroute command runs only on Unix/Linux, although there is a Windows version called tracert. The ifconfig and iptables commands only exist on Unix and Linux systems.
Ed suspects that his workstation is experiencing TCP/IP communication problems. Which of the following commands can he use to confirm that the computer's TCP/IP stack is loaded and functioning? (Choose all correct answers.)
(1) ping 127.0.0.1 (2) ping localhost . The IP address 127.0.0.1 is a dedicated loopback address that directs outgoing IP traffic directly into the incoming IP traffic buffer. The hostname localhost resolves to the 127.0.0.1 address on every TCP/IP system. Ed can therefore ping either the hostname or the IP address to test that his TCP/IP stack is functional. Loopback is not a hostname for the loopback address, and 127.0.0.0 is a network address, not a host address, so it will not work in this situation.
Which of the following application layer protocols includes a program that enables a user to log on to a network device and execute commands on the remote system using a command-line interface? (Choose all correct answers.)
(1) telnet (2) FTP Both Telnet and FTP are protocols that include command-line client applications, with Telnet providing terminal emulation and FTP file transfer functionality. SNMP and DNS are both application layer protocols, but neither one includes a program. Nslookup has a command-line interface but it executes commands on the local system, not a remote one.
Ed is working the help desk at a local computer store, and he receives a call from a customer trying to set up a home network using Windows 10 and wired Ethernet equipment. The customer reports that, from her computer, she cannot access the two other computers in the house, nor can she access the Internet. Ed asks her to run the ipconfig /all command and read the results to him. She says that her IP address is 172.16.41.2, her subnet mask is 255.255.255.0, and her default gateway is 172.16.43.1. Which of the following could conceivably be the cause of the customer's problem? (Choose all correct answers.)
(1) the Customer has an incorrect subnet mask (2) the customer has an incorrect default gateway . The computer could have an incorrect subnet mask or an incorrect default gateway address. Because the customer's computer has an IP address on the 172.16.41.0/24 network, her default gateway address should also be on that network. However, if the subnet mask value is incorrect and should be 255.255.0.0, then the default gateway address is correct.
Which of the following parameters enables you to specify the time-to-live (TTL) value of the messages ping transmits?
-i. Running the ping tool with the -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -t parameter causes the ping tool to send messages to the target continuously until you manually stop it. The -n parameter enables you to specify the number of messages the ping tool should transmit. The -a parameter resolves an IP address you specify as the target to a hostname.
Which of the following parameters causes the ping tool to transmit messages continually until manually halted?
-t . Running the ping tool with the -t parameter causes it to send messages to the target continuously until you manually stop it. The -n parameter enables you to specify the number of messages the ping tool should transmit. The -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -a parameter resolves an IP address you specify as the target to a hostname.
Ralph is setting up a wireless network using the 2.4 GHz band. Which of the following channels should he use to avoid channel overlap? (Choose all correct answers.)
1, 6, 11
Alice has recently created a new perimeter network for the company's web server cluster, along with a router to connect it to the internal network. When she is finished, she sends Ralph an email instructing him to run the following command on his Windows workstation so that he can access the servers on the perimeter network. What function does the IP address 192.168.87.226 perform in this command? route add 192.168.46.0 MASK 255.255.255.0 192.168.87.226
192.168.87.226 is the address of one of the router's interfaces. The correct syntax for the Windows route add command is to specify the destination network address, followed by the subnet mask for the destination network, followed by the address of the router interface on the local network that provides access to the destination network. Therefore, 192.168.87.226 is the address of the router interface on the internal network, where Ralph's workstation is located.
Ralph has to spend the day completing a twisted pair cable installation in his office. Contractors have already pulled the cables through the walls and ceilings. Ralph only has to attach connectors to the ends of the cables, both internal cable runs and patch cables. Which of the following tools will Ralph need? (Choose all correct answers.)
A crimper is a plier-like tool that cable installers use to attach RJ45 connectors to patch cables. A punchdown tool is a tool that cable installers use to attach keystone connectors to cable ends, for use in wall plates and patch panels. A telepole is a device used to run cables through walls, floors, and ceilings, but since the cable runs have already been pulled, Ralph will not need this tool. A pigtail splicer is a tool used only in fiber-optic cable installations.
Which of the following statements describes the difference between a packet sniffer and a protocol analyzer?
A packet sniffer is a tool that captures packets for the purpose of traffic analysis, but cannot view their contents. A protocol analyzer is a tool that enables a user to view the contents of packets captured from a network. In practice, however, packet sniffer and protocol analyzer capabilities are usually integrated into a single tool. Both tools can function in promiscuous mode to capture packets from an entire network.
Ralph is the administrator of a small company's wireless network. He has recently discovered evidence that users outside of the company's office space have been accessing its wireless network. The office is located in a narrow space against the building's outside wall. Ralph is concerned that the network's wireless access point is extending coverage outside the building. Speaking with a consultant friend of his, Ralph is advised to install a different type of antenna on his access point. Which of the following antenna types would most likely help Ralph to alleviate the problem?
A patch antenna is a flat device that transmits signals in a half-spherical pattern. By placing the antenna against the building's outer wall, Ralph can provide coverage inside the building and minimize coverage extending to the outside. A dipole antenna is another name for the omnidirectional antenna usually provided with an access point. A unidirectional antenna directs signals in a straight line, which would not provide the coverage Ralph needs. A Yagi antenna is a type of unidirectional antenna.
Ed is a first-tier support technician. He receives the help calls listed here. His job is to assign them priorities based on their severity. Which of the following should be the problem that receives the lowest priority?
A problem that affects the entire network should be given highest priority. This includes a mission-critical backbone router. Problems that affect multiple LANs or an entire department are generally given the next highest priority. An application problem that affects a shared application server on a LAN should be given the next highest priority. A problem with a single user's computer should be given the lowest priority if the other problems have been reported.
Which of the following is a network-wide problem?
A problem with a router tht connects an entire network to the internet. Any problem that affects all the users on the network is a network-wide problem and should be given the highest priority. An example of this would be a problem with an Internet router. All other problems listed do not affect the entire network.
Ed is a first-tier support technician. He receives the help calls listed here. His job is to assign them priorities based on their severity. Which of the following should be the problem that receives the highest priority?
A problem with the mission critical backbone that effects the entire network. A problem that affects the entire network should be given highest priority. This includes a mission-critical backbone router. Problems that affect multiple LANs or an entire department are generally given the next highest priority. An application problem that affects a shared application server on a LAN should be given the next highest priority. A problem with a single user's computer should be given the lowest priority if the other problems have been reported.
Ed is implementing a web server farm on his company's network and has created a perimeter network on which the web servers will be located. The perimeter network is using the network IP address 192.168.99.0/24. He has also installed a router connecting the perimeter network to the internal network, which uses the 192.168.3.0/24 network address. The IP addresses of the router's interfaces are 192.168.3.100 and 192.168.99.1. Ed needs to access the web servers from his Windows workstation on the internal network, but right now, he cannot do so. Because he needs to have a different router specified as his default gateway, Ed decides to add a route for the perimeter network to his computer's routing table. Which of the following commands will create a routing table entry that enables Ed to access the perimeter network?
A route add 192.168.99.0 Mask 255.255.255.0 192.168.3.100 The correct syntax for the Windows route add command is to specify the destination network address, followed by the subnet mask for the destination network, followed by the address of the router interface on the local network that provides access to the destination network. The other options do not specify the correct addresses in the syntax.
You have a problem with a server or other network component that prevents many users from working. What type of problem is this?
A shared resource problem If a problem lies within a specific server or other network component that prevents many users from working, it is a shared resource problem. A problem that lies within resources that provide services to the entire network is a network-wide problem. System-wide problems put a specific computer out of commission, preventing a user from getting any work done. An application problem is a problem that affects only a single user's access to a device or application.
Ralph is having trouble providing satisfactory wireless network performance to some executive offices at the far end of the building. The offices have heavy doors and insulated walls for sound dampening, and the occupants typically leave their doors closed during work hours. Which of the following types of radio signal interference is Ralph trying to overcome?
Absorption is a type of interference that occurs when radio signals have to pass through barriers made of dense materials, such as walls and doors. In this case, the construction of the barriers has made them more formidable. Reflection is when signals bounce off of certain surfaces, such as metal. Refraction is when signals bend as they pass through certain barriers, such as glass or water. Diffraction is when signals have to pass around barriers to reach a particular destination. All of these phenomena can weaken the radio signals used in wireless networking, but absorption is the primary problem for Ralph in this case.
Which of the following tools can you use to test the optical loss in a fiber-optic cable?
An optical loss test set (OLTS) identifies signal loss in fiber optic cabling. A time domain reflectometer (TDR) measures electrical signals in copper-based cabling, not light signals. A light meter measures the strength of light signals on fiber optic cable, but it cannot generate the signal needed to test optical loss. Wiremap testers are used only on copper cables, not fiber optic.
Ed has discovered that some of the twisted pair cable runs on his newly installed Ethernet network are well over 100 meters long. Which of the following problems is his network likely to experience due to cable segments that are greater than the specified length?
Attenuation is the weakening of a signal as it travels long distances, whether on a wired or wireless medium. The longer the transmission distance, the more the signal weakens. Cable length specifications are designed in part to prevent signals from attenuating to the point at which they are unviable. Jitter, crosstalk, and electromagnetic interference (EMI) are all conditions that can affect the performance of a wired network, but they are not directly related to the length of the cable.
A user calls the company's IT help desk to report that she has received an error message on her Windows workstation. The error states that her computer has an IP address that is duplicated on the network. Ralph is concerned that there might be a configuration problem with the DHCP servers on the network. He suspects that there are DHCP servers configured with scopes that overlap, resulting in two DHCP servers assigning the same IP addresses to different clients. He is worried that they are about to receive a flood of calls reporting the same problem. Alice reassures Ralph, telling him that it cannot be a DHCP problem and that there must be two computers that are manually configured with the same IP address. How does Alice know this?
Because DHCP clients use ARP broadcast to check for duplicate IP addresses. When a Dynamic Host Configuration Protocol (DHCP) client is offered an IP address by a DHCP server, the client broadcasts Address Resolution Protocol (ARP) requests using that address before accepting it. If another computer on the local network is using the offered address, the computer responds to the ARP request and the DHCP client declines the address. The DHCP server then offers another address. DNS queries and routing table checks are not reliable means of checking for duplicate IP addresses. It is possible to have two DHCP servers on the same local network, but they must be configured with scopes that do not overlap.
Ed is working the help desk at a local computer store, and he receives a call from a customer trying to set up a home network using Windows 10 and wired Ethernet equipment. The customer reports that, from her computer, she can see the two other computers in the house, but she cannot access the Internet. Ed asks her to run the ipconfig /all command and read the results to him. She says that her IP address is 172.16.41.2, her subnet mask is 255.255.255.0, and her default gateway is 172.16.43.1. Which of the following is most likely the cause of the customer's problem?
Because the customer can access the other two computers in the house, Ed knows that her IP address and subnet mask are properly configured that the network cable is plugged in and functional. Ed also knows that the computer's DNS record does not play a role in outgoing connections. The problem is most likely the default gateway because the gateway address the customer specified is on another network, 172.16.43.0, rather than on her own network, 172.16.41.0
Users on Ed's 802.11n wireless network are dropping their connections intermittently. Which of the following might help to resolve the problem?
Change the channel the devices are using. If the users are losing their connections due to interference from other types of devices, changing the channel alters the frequency the network uses and can enable it to avoid the interference. The other options are not likely to affect any condition that would cause users to drop their connections.
Ralph is experiencing poor performance on his home 802.11n wireless network. Ralph lives in a large apartment complex, and when he runs a Wi-Fi analyzer, he sees many other nearby networks using the often-recommended channels 1, 6, and 11 on the 2.4 GHz frequency. Using the 5 GHz frequency is not an option for Ralph's equipment. What should Ralph do to improve his network performance?
Configure his equipment to use channel 9. The 2.4 GHz band used by wireless LANs (WLANs) consists of channels that are 20 (or 22) MHz wide. However, the channels are only 5 MHz apart, so there is channel overlap that can result in interference. Channels 1, 6, and 11 are the only channels that are far enough apart from each other to avoid any overlap with the adjacent channels. This is why they are often recommended. However, in Ralph's case, these channels are too crowded with other networks. Ralph should therefore use a channel that is as far as possible from the crowded ones. Channels 2, 5, and 10 are all immediately adjacent to a crowded channel, but channel 9 is at least two channels away from the nearest crowded channel. Therefore, Ralph should configure his equipment to use channel 9.
Ed has discovered that, on some of his newly installed twisted pair cable runs, the installer has stripped away nearly a foot of the cable sheath at each end and has untwisted the wire pairs before attaching them to the connectors. Which of the following problems is the network more likely to experience due to the untwisted wires?
Crosstalk is a type of interference that occurs on copper-based networks when in a signal transmitted on one conductor bleeds over onto another nearby conductor. Twisted pair cables, which have eight or more conductors compressed together inside one sheath, are particularly susceptible to crosstalk. Twisting each of the separate wire pairs tends to reduce the amount of crosstalk to manageable levels. Untwisting the pairs leaves them more susceptible to crosstalk. Jitter, attenuation, and electromagnetic interference (EMI)are all conditions that can affect the performance of a wired network, but they are not directly related to untwisted wire pairs.
Ed has installed a separate 802.11n wireless network for guest users working in his company's offices. The guest network is unsecured, and Ed has recently become aware that people outside the building are able to access it. It is not possible to move the access point, and it must run at maximum power to reach the entire building. Which of the following is the most convenient way to prevent users outside the building from accessing the guest network while leaving it available to users inside the building?
Disable SSID broadcasting. Moving the access point to the center of the building will keep as much of its operational range inside the structure as possible. If the signals still reach outside the building, Ed can reduce the power level of the access point until the network is only accessible inside. Disabling SSID broadcasts will not defeat dedicated attackers, but it can prevent casual intruders from accessing the network. MAC filtering would require Ed to configure the access point with the MAC addresses of all devices that will access the network, which would be impractical in this case. The network is unsecured, so there is no passphrase to change, and a frequency change will have no effect on the problem.
In the standard troubleshooting methodology, which of the following steps appears last but must actually be practiced throughout the troubleshooting process?
Document findings, actions, and outcomes. Documenting everything you discover and everything you do is a crucial part of the troubleshooting method that must begin before you take any other action whatsoever. However, it appears as the last step in the troubleshooting methodology.
A user calls Alice at the IT help desk and reports that she is having intermittent problems accessing both local servers and Internet websites. Which of the following potential problems can Alice rule out immediately?
Duplicate IP addresses. Operating systems detect duplicate IP addresses immediately and display error messages or notifications on the computers involved. Therefore, the user with the problem would have been informed immediately if another system was using her IP address. All of the other options are possible causes of the problem that are more difficult to troubleshoot.
Which step of the troubleshooting model involves identifying whether hardware or software has been recently installed or reconfigured?
During the troubleshooting process, you must establish whether anything has changed. This typically involves asking the user whether any new or existing hardware or software has been installed or reconfigured.
Alice's network has been experiencing intermittent service slowdowns and outages ever since the company moved into their new building. She has tried every troubleshooting procedure she can think of and hasn't been able to determine the cause. One particularly irritating user, hoping to be the squeaky wheel that gets the grease, has taken to calling Alice every time he experiences a problem. One day, as she is working in the datacenter, Alice notices that the user calls her every time she hears an additional humming noise begin. After examining the doors in the hallway, Alice realizes that the racks containing her switches are located right next to the elevator machinery room. Which of the following conditions is probably causing the network communication problem?
EMI Elevator machinery, fluorescent light fixtures, and other electrical devices in an office environment can generate magnetic fields, resulting in electromagnetic interference (EMI). When copper-based cables are located too near to such a device, the magnetic fields can generate an electric current on the cable that interferes with the signals exchanged by network devices. If the network users experience a problem every time the elevator machinery switches on, EMI is a likely cause of the problem. Near end crosstalk (NEXT), far end crosstalk (FEXT), and attenuation can all cause intermittent network communication problems, but they cannot be caused by elevator machinery.
When troubleshooting, you begin by taking steps to identify the problem. After you do this, which of the following steps should you perform next?
Establish a theory of probable cause
In which troubleshooting step is a trouble ticket created?
Identify the problem.
Ralph has a wired home network with three Windows computers, a switch, and a cable modem/router that provides access to the Internet. All three computers are able to access the Internet, but none of them can access file system shares on the others. Which of the following is the most likely cause of the problem on the three network computers?
Incorrect ACL settings. The problem is most likely incorrect ACL settings. Because the computers are all able to access the Internet, their TCP/IP settings, including their IP addresses, subnet mask, and default gateway address, must be correct. However, if the users do not have the correct permissions in the access control lists (ACLs) of the file system shares, they will not be able to access the shares over the network.
Ralph is adding new workstations to his wireless network, which uses an access point that is configured to use WPA2 encryption. However, after configuring the wireless network adapter on the first workstation, Ralph finds that it is not connecting to the network. The access point is listed on the Available Networks display, and there are no error messages or indications of a problem, just a failure to connect. Which of the following is most likely to be the problem?
Incorrect Passphrase. Specifying the wrong passphrase for the encryption protocol is the most common cause of a failure to connect to the network with no indication of an error. Channel overlap or a poor signal-to-noise ratio, caused by a microwave oven or other device, could result in a weak signal, either of which would be indicated in the list of available networks. Incorrect SSID is not likely to be the error, as long as Ralph selected the access point from the list.
Alice has been asked to update an accounts receivable spreadsheet with information about the day's incoming payments, a task she has never performed before. After locating and opening the spreadsheet on the network server, she types in her new information, but when she attempts to save the changes, she receives an error message that directs her to save the file on her local drive instead of the network server. Which of the following is the probable cause of the problem?
Incorrect filesystem ACL settings. Because Alice is able to access the server and open the spreadsheet file, the problem is not related to blocked ports, firewall settings, or an untrusted certificate. The problem is most likely that though she has the necessary filesystem access control list (ACL) permissions to open and read the file, she does not have the permissions needed to modify it.
Alice's company is opening a new branch office, and Alice is responsible for building the Active Directory domain controller for that office. She installs a new Windows server and configures it as a domain controller and then ships it to the new office site. However, once it arrives and is connected to the home office network, the new domain controller fails to synchronize with the existing ones at the home office. Which of the following could be the cause of the problem?
Incorrect time. If the time on the Active Directory domain controller at the new office is more than five minutes off of the time held by domain controller with the PDC Emulator role at the home office, then the new domain controller will not sync. Duplicate IP addresses or an incorrect default gateway address would prevent the new domain controller from connecting to the home office network. A server hardware failure would manifest as an outage far more serious than a domain controller synchronization issue.
Which of the following terms describes a connectivity problem on wired networks that is caused by individual packets that are delayed due to network congestion, different routing, or queuing problems?
Jitter. When individual packets in a data stream are delayed, the resulting connectivity problem is called jitter. Although this condition might not cause problems for asynchronous applications, real-time communications, such as Voice over IP or streaming video, can suffer interruptions, from which the phenomenon gets its name. Latency describes a generalized delay in network transmissions, not individual packet delays. Attenuation is the weakening of a signal as it travels through a network medium. A bottleneck is a condition in which all traffic is delayed, due to a faulty or inadequate component.
Which of the following indicators can you use to determine whether an adapter is connected to a functioning hub or switch?
Link Pulse LED The link pulse LED indicates the adapter is connected to a functioning hub or switch. The speed LED specifies the data rate of the link. The collision LED lights up when collisions occur. There is no status LED on a network interface adapter.
Ed has installed a separate 802.11n wireless network for guest users working in his company's offices. The guest network is unsecured, and Ed has recently become aware that people outside the building are able to access it. Which of the following steps can Ed take to prevent users outside the building from accessing the guest network, while leaving it available to unauthenticated users inside the building?
Moving the access point to the center of the building will keep as much of its operational range inside the structure as possible. If the signals still reach outside the building, Ed can reduce the power level of the access point until the network is only accessible inside. Disabling SSID broadcasts will not defeat dedicated attackers, but it can prevent casual intruders from accessing the network. MAC filtering would require Ed to configure the access point with the MAC addresses of all devices that will access the network, which would be impractical in this case
Ralph purchases some 802.11a wireless network adapters for desktop computers at a yard sale, which he intends to use on his 802.11g home network. He installs one of the adapters in a computer and attempts to connect it to the network, but he can't see his SSID. He tries a different adapter, thinking the first one might be broken, but that one does not work either. What can Ralph do to resolve the problem and connect the computer to his network?
Nothing. 802.11a equipment cannot connect to an 802.11g network. Wireless LAN equipment built to the 802.11a standard can only use the 5 GHz frequency. However, an 802.11g access point can only use the 2.4 GHz frequency. Therefore, the network adapters cannot connect to Ralph's access point.
Which of the following cable testing tools are used only on fiber-optic networks?
OTDR An optical time domain reflectometer (OTDR) is a device that transmits light pulses over a fiber-optic network and measures the time interval and strength of the returning pulse, to measure the length of the cable run. An OTDR can be used to locate fiber-optic cable breaks, as well as characterize a cable run's reflectance, optical return loss, and other characteristics. Multimeters, tone generators, and punchdown tools are all devices that work only with copper networks.
Which of the following troubleshooting tools is not used to test copper cabling installations?
OTDR. An optical time domain reflectometer (OTDR) is a device that transmits light pulses over a fiber-optic network and measures the time interval and strength of the returning pulse, to measure the length of the cable run. An OTDR can be used to locate fiber-optic cable breaks, as well as characterize a cable run's reflectance, optical return loss, and other characteristics. Multimeters, tone generators, and wiremap testers are all devices that work only with copper networks
Clients of Ralph's company are calling to complain that when they try to access the company's website, they see an error message stating that the website has an untrusted security certificate. They are afraid that they are connecting to an unprotected site or that the site has been taken over by hackers? What must Ralph due to address this problem?
Obtain an SSl Certificate from a trusted third-party company. For the website's Secure Socket Layer (SSL) certificate to be trusted, it must be signed by a source that both parties in the transaction trust. Many security firms are in the business of providing SSL certificates to companies that have provided them with confirmation of their identities. This is what Ralph must do to prevent the error message from appearing to the company's clients. Creating a self-signed certificate or installing a certification authority in-house are not sufficient and are probably already the cause of the problem. Users are not likely to be convinced that everything is all right.
Alice's company has moved to a building that was prewired for Ethernet. However, since installing the company's Gigabit Ethernet equipment using the existing cable runs, performance has been poor. After performing some packet captures and analyzing the traffic samples, Alice discovers that there are a great many Ethernet frames being retransmitted. Next, she examines the cable runs in the drop ceilings. They do not appear to be overly long, and they do not appear to run near any major sources of electromagnetic interference. Which of the following could be the problem?
Of the options provided, the only possible source of the problem is that the cable runs are using a cable type not rated for Gigabit Ethernet. Some older buildings might still have Category 3 cable installed, which was used in the original twisted pair Ethernet specification. Cat3 is unsuitable for use with Gigabit Ethernet in many ways and can result in the poor performance that Alice is experiencing. A cable installation with runs wired using different pinout standards will not affect performance as long as each run uses the same pinouts at both ends. Gigabit Ethernet will not function at all if only two wire pairs are connected. The transceivers are located in the equipment that Alice company brought from the old location, so they are not mismatched.
Which of the following protocols does the traceroute utility on Unix and Linux systems use to test TCP/IP connectivity?
On Unix and Linux systems, the traceroute utility tests TCP/IP connectivity by transmitting User Datagram Protocol (UDP) messages. This is unlike the tracert utility on Windows systems, which uses Internet Control Message Protocol (ICMP) messages. Neither version uses TCP or HTTP.
Ralph recently bought an old Ethernet hub and some twisted pair cables at a garage sale and wants to use them to build a home network. He plugs two computers into the hub using the cables but finds that the computers are unable to communicate. Then he notices that one of the ports in the hub is labeled with an X. He tries plugging one of the computers into the X port, and now they can communicate. Which of the following statements is the most likely explanation for this behavior?
One of the cables is a crossover cable Older Ethernet hubs do not auto negotiate crossovers. Instead, they have an X (or uplink) port that provides a connection without a crossover circuit, so you can connect one hub to another. If both of the cables had been standard straight-through Ethernet cables or if both had been crossover cables, then plugging them into two regular ports should have worked. Because plugging one cable into the X port worked, this means that only one of the cables must be a crossover cable. The problem, therefore, was the cable, not the port. The X port does not provide extra strength to the signals.
Ralph has installed a new Category 5e cable run himself. He has attached keystone connectors to both ends of the cable, mounted the office-side connector to a wall plate, and mounted the datacenter connector into a patch panel. Then he took a patch cord and connected the patch panel port to an open port in one of the network switches. However, the LED on the switch port does not light. What should Ralph do?
Plug a computer into the wall plate. For the link pulse LED on the switch port to light up, there must be a completed connection between the switch and a computer at the other end. None of the other options will cause the LED to light.
Ralph has two computers that he long ago networked together by plugging one end of an Ethernet cable into each machine. He recently bought an old Ethernet hub at a garage sale and wants to use it to expand his network. The hub has four numbered ports and a fifth port marked with an X. Ralph plugs one computer into port 1 using his existing cable and buys a new cable to plug the other computer into port 4. The two computers cannot communicate, however. Which of the following solutions will not enable his computers to communicate?
Plug the computer with the old cable into the X port. The problem is unlikely to be a bad hub port or a bad cable, so moving the cable from port 4 to port 2 will not help. The problem is the crossover circuit between the two computers. The two systems were once connected directly together, which means that Ralph was using a crossover cable. The hub also provides a crossover circuit (except in the X port), and old hubs often do not auto negotiate crossovers. Therefore, the connection has two crossovers, which is the equivalent of wiring transmit pins to transmit pins, instead of transmit pins to receive pins. All of the other options eliminate one of the crossover circuits, enabling the computers to be wired correctly.
Ed has configured his workstation to use IPsec encryption for network communications. Which of the following tools can he use to verify that his network traffic is encrypted?
Protocol analyzer. A protocol analyzer is a tool that enables a user to view the contents of packets captured from a network. In Ed's case, if IPsec is properly implemented, he should be able to see that the data in packets captured from his workstation is encrypted. A packet sniffer is a tool that captures packets for the purpose of traffic analysis, but cannot view their contents. In practice, however, packet sniffer and protocol analyzer capabilities are usually integrated into a single tool. A port scanner examines a system, looking for open TCP and UDP ports, and a multimeter is a tool that reads voltages on electrical circuits. Neither of these tools can examine packet contents.
Ralph is a new hire working on a network that uses Cat5 unshielded twisted pair cable, which was installed several years ago. Over time, some of the paper labels that the original cable installers used to identify the wall plates and patch panel connectors have worn away or fallen off. As a result, Ralph has quite a few cable runs that he is unable to identify. After checking with his supervisor, Ralph discovers that the company has no cable testing equipment and is unwilling to hire a consultant just to identify cable runs. What is the most inexpensive tool Ralph can use to associate unlabeled wall plates with the correct patch panel ports?
Ralph is a new hire working on a network that uses Cat5 unshielded twisted pair cable, which was installed several years ago. Over time, some of the paper labels that the original cable installers used to identify the wall plates and patch panel connectors have worn away or fallen off. As a result, Ralph has quite a few cable runs that he is unable to identify. After checking with his supervisor, Ralph discovers that the company has no cable testing equipment and is unwilling to hire a consultant just to identify cable runs. What is the most inexpensive tool Ralph can use to associate unlabeled wall plates with the correct patch panel ports?
Ralph is responsible for the network installation in a new building purchased by his company, and he has elected to have Category 6 unshielded twisted pair cable installed. The company president has asked him if it is possible to run their Gigabit Ethernet network using two of the wire pairs in the cable, while using the other two pairs for telephone connections. Ralph is not sure, so he sets up a lab network using cables with only two pairs connected. When he plugs computers into the switch and turns them on, the LEDs labeled 1000 light up, indicating that a Gigabit Ethernet connection has been established. Ralph gets excited at the thought of how much money he might save the company by using the same cable for both telephone and data. However, while the LED is lit, he can't seem to connect to another system over his test network. Which of the following describes what he must do to correct the problem?
Ralph must use all four wire pairs for a gigabit Ethernet connection. The auto negotiation mechanism is not the problem, nor is the pinout standard or Ralph's wire pair selection. The speed auto negotiation mechanism in Gigabit Ethernet uses only two wire pairs, so although the LEDs do light up successfully, a functional Gigabit Ethernet data connection requires all four wire pairs.
Ralph is deploying an 802.11n wireless network for a client that calls for the best possible security without deploying additional servers. When setting up the wireless access point, Ralph disables SSID broadcasts, selectsWi-Fi Protected Access security with preshared keys (WPA-PSK), and configures MAC address filtering. Which of the following statements about the security of this arrangement is true?
Ralph should use Wi-fi protected Access II (WPA2) instead of WPA, because it is more resistant to certain types of attacks WPA has been found to be vulnerable, and WPA2 was designed to address those vulnerabilities, so Ralph should use WPA2 instead of WPA. Suppressing SSID broadcasts does not prevent users from connecting to the network, and MAC filtering strengthens security without exposing MAC addresses to undue risk.
Which of the following is not a potential solution for an IEEE 802.11g wireless computer that has intermittent problems connecting to an IEEE 802.11b/g access point?
Replace the access point with a model that supports 802.11n. Which of the following is not a potential solution for an IEEE 802.11g wireless computer that has intermittent problems connecting to an IEEE 802.11b/g access point?
hich of the following parameters enables you to specify the number of messages the ping tool transmits?
Running the ping tool with the -n parameter enables you to specify the number of messages the ping tool should transmit with each execution. The -t parameter causes the ping tool to send messages to the target continuously until you manually stop it. The -i parameter enables you to specify the time-to-live (TTL) value of the messages ping transmits. The -a parameter resolves an IP address you specify as the target to a hostname.
After connecting a tone generator to the green wire at one end of a twisted pair cable run, Ralph proceeds to the other end of the cable and touches the locator to each of the eight pins in turn. The green wire and the green striped wire both produce a tone. What type of wiring fault has Ralph discovered?
Short Circuit The first and most essential test that installers must perform on every cable run is a continuity test, which ensures that each wire on both ends of the cable is connected to the correct pin and only the correct pin. If a pin on one end of a cable run is connected to two or more pins on the other end, you have a short circuit.
To save the company money and to provide some new hires with Gigabit Ethernet connectivity, Ralph has installed some new Category 5e cable runs, connecting his company's datacenter with a newly rented office at the far end of the building. However, the new users are complaining of intermittent connectivity problems. The company brings in a cabling contractor to investigate, and his diagnosis is attenuation. Which of the following solutions will most likely be a sure solution to the problem?
Shorten the cable runs. Attenuation is the weakening of the signals as they traverse the network medium. In this case, it is most likely the result of cable runs that exceed the 100 meter maximum defined in the Ethernet twisted pair specification. Therefore, shortening the cable runs will be likely to solve the problem. All of the Ethernet twisted pair specifications have a 100 meter maximum length, so running the network at a slower speed, installing a higher grade cable, and installing higher end network adapters might have no effect if the runs are overly long.
Alice has a network with a Domain Name System (DNS) server, a proxy server, and an Internet router. A user is complaining that she suddenly can't connect to hosts on her own local area network (LAN) and other internal LANs, and she can't access hosts on the Internet. What is the likeliest problem?
Since only one user is reporting the problem, the user's computer and its configuration are the likeliest suspect components. ADNS, proxy, or router problem would affect more than one user.
Ed is experiencing bad network performance on some new twisted pair cable runs that he recently had installed. After ruling out all other causes, he tests the cables with a tone generator and locator and finds no faults. Finally, he examines the cable connectors more closely and finds that, while the pins at one end of the cable are correctly connected to their corresponding pins at the other end, in some cases there are two solid color wires twisted together in a pair. Which of the following types of faults has Ed discovered?
Split pairs. A split pair is a connection in which two wires are incorrectly mapped in exactly the same way on both ends of the cable. Each pin on one end of the cable is correctly wired to the corresponding pin at the other end, but the wires inside the cable used to make the connections are incorrect. In a properly wired connection, each twisted pair should contain a colored signal wire and a striped ground wire. In a split pair, you can have two signal wires twisted together as a pair. This can generate excessive amounts of crosstalk, corrupting both of the signals involved. Because all of the pins are connected properly, a tone generator and locator cannot detect this fault. An open circuit would manifest as a failure to detect a tone on a wire, indicating that there is either a break in the wire somewhere inside the cable or a bad connection with the pin in one or both connectors. A short is when a wire is connected to two or more pins at one end of the cable or when the conductors of two or more wires are touching inside the cable. Having transposed pairs is a fault in which both of the wires in a pair are connected to the wrong pins at one end of the cable. All three of these faults are detectable with a tone generator and locator.
Which step of the troubleshooting model involves replacing components until a faulty hardware device is identified?
Test the theory to determine the cause. After you have established a theory of probable cause, you can try to test the theory by replacing hardware components one by one until you find the faulty device.
Alice is troubleshooting a Windows server, and while doing so she runs the following command: ping 127.0.0.1. The command completes successfully. What has Alice proven by doing this?
That the computer's TCP/IP networking stack is loaded and functioning. The IP address 127.0.0.1 is a dedicated loopback address that directs outgoing IP traffic directly into the incoming IP traffic buffer. A successful ping test using that address indicates that the computer's TCP/IP stack is functioning properly, but the traffic never reaches the network adapter or the network, so the test does not confirm that the adapter is functioning or that the computer has a correct IP address for the network.
Ed is working the help desk at a local computer store, and he receives a call from a customer trying to set up a home network using Windows 10 and wired Ethernet equipment. The customer reports that she cannot access the other two computers in the house, nor can she access the Internet. Ed asks her to run the ipconfig /all command and read the results to him. She says that her IP address is 192.168.0.2, her subnet mask is 255.255.255.0, and her default gateway is 192.168.0.1. Which of the following is most likely the cause of the customer's problem?
The Customer's network cable is unplugged. The customer's IP address, subnet mask, and default gateway are appropriate for her home network. There is nothing wrong with having a zero in the network address. Therefore, of the options presented, the only logical choice is that the network cable is unplugged.
Which of the following Windows commands enables you to create a new entry in the ARP cache?
The arp -s command enables you to create a cache record specifying the MAC address and its associated IP address. The arp -N command enables you to display the ARP cache entries for a specified network interface. The arp -d command is for deleting cache entries. The arp -a command displays the entries in the ARP table stored in its cache.
Alice receives a call in which a user reports that he is unable to send print jobs to the network-attached workgroup printer near his desk. Which of the following tasks should Alice perform first?
The first phase of the troubleshooting process is gathering information. Learning whether the printer is accessible over the network can help Alice to isolate the location of the problem and develop a theory of probable cause. Installing drivers, checking switches, and upgrading firmware are all part of a later phase in the troubleshooting process: testing a theory to determine the cause of the problem.
Which of the following command-line utilities can only run on Unix and Linux systems?
The ifconfig command runs only on Unix and Linux systems. The ping and netstat utilities run on both Windows and Unix/Linux systems. The ipconfig and tracert commands run only on Windows, although there is a Unix/Linux version of tracert called traceroute.
Alice is supporting a network that consists of four internal local area networks (LANs) with 50 users each. Each internal LAN uses twisted pair Gigabit Ethernet links that connect the users to a switch. Each of the four switches connects to a backbone router. All of the routers connect to the same backbone network, which has a single additional router to connect the company's network to the Internet. Users on all of the internal LANs are complaining that, when they came in this morning, they could not access the Internet, although they could access resources on all of the LANs with no problems. Which network component is the likeliest source of the problem in this scenario?
The internet router. In this scenario, all of the internal users are experiencing problems connecting to the Internet, so the router that provides access to the Internet is the suspected component. Since users can connect to resources on the internal LANs, the problem probably is not in any of the routers connecting the LANs to the backbone or the backbone cable itself. This also eliminates the probability that the switches on the LANs are the problem.
Ed has recently discovered a rogue DHCP server on his network. After disabling the server, he now needs to terminate all of the rogue IP address leases currently held by DHCP clients on the network and have them request new leases from the authorized DHCP server. Which of the following commands must he use on each client to do this? (Choose all correct answers.)
The ipconfig /release command terminates the current DHCP address lease. Then, the ipconfig /renew causes the client to begin the process of negotiating a new lease, this time with an authorized DHCP server. Dump, lease, and discard are not valid ipconfig parameters.
Which of the following command-line utilities enables you to generate Domain Name System (DNS) request messages?
The nslookup tool enables you to generate DNS request messages from the command line and send them to a specific DNS server. The other options listed are not DNS utilities.
While working in her company's datacenter, Alice notices that the LEDs on most of the network switch ports are green, but there are several that are orange. Alice asks several people why this is so and receives several different answers. Which one of the following answers is correct?
The orange Leds indicate that the device is connected to the switch at a relativel slow speed. Green LEDs indicate the device is running at the full speed supported by the switch, whereas orange LEDs indicate that the device is running at a reduced speed. If no device is connected, the LED does not illuminate at all. The LED does not indicate the occurrence of collisions or the type of device connected to the port
Ralph is a network administrator who has had a Windows user report difficulties accessing certain other computers on the network. Ralph determines that the user is only experiencing problems when trying to connect to a system on the far side of a router. Ralph therefore decides to inspect the routing table on the user's computer. Which of the following tools can he use to do this? (Choose all correct answers.)
The route print tool displays the contents of the routing table on a Windows computer. So does the netstat -r command. The nbtstat and nslookup tools cannot display the routing table.
In which troubleshooting step do you try to duplicate a network problem to "divide and conquer" by logically and methodically eliminate elements that aren't the source of the problem?
The second step in troubleshooting is to attempt to duplicate a problem and develop a theory of its probable cause. As you troubleshoot a problem, you then test your theory to confirm your findings. You complete the other troubleshooting steps after the specific cause has been identified.
Which TCP/IP utility should you use to most easily identify a malfunctioning router on your network?
The traceroute (or tracert) utility can locate a malfunctioning router by using an Echo Request messages with incrementing TTL values. ifconfig is a network configuration utility for Unix and Linux systems; ping can test connectivity to another TCP/IP system, but it cannot locate a malfunctioning router; and netstat displays information about network connections and traffic but cannot locate a malfunctioning router.
Which of the following Windows tools uses ICMP messages and manipulates IPv4 time-to-live values to illustrate the route packets take through an internetwork?
Tracert. The Windows tracert tool transmits a series of ICMP messages with incrementing time-to-live (TTL) values, which identify each router on the path the packets take through the network. ping uses ICMP, but it does not manipulate TTLvalues. netstat, route, and nslookup do not use ICMP messages, nor do they manipulate TTLvalues when performing their normal functions.
Alice is a new hire at Adatum Corp., and when she asks about wireless network access for her laptop, she is given an SSID and a WPA2 passphrase. Later, in the lunchroom when she tries to connect her laptop to the network, she cannot see the SSID she was given in theavailable networks list, although she can see other networks. What should Alice do next to try to resolve the problem?
Type the SSID in manually. It is possible that the wireless access point has been configured not to broadcast the network's SSID as a security measure, so Alice should first attempt to access it by typing the SSID in manually. She would not be able to type in the WPA2 passphrase until she is connecting to the SSID. Moving the laptop closer to the access point or away from possible sources of electromagnetic interference might be solutions to the problem, but they should not be the first thing Alice tries.
Ralph has been asked to create some new patch cables that will be used to connect patch panel ports to the network switches. He has been told that the patch panel connectors are all wired using the T568A pinout standard. Which of the following instructions should Ralph use when creating the patch cables?
Use either standard, as long as both ends are the same. Either the T568A or the T568B pinout standard is acceptable. The patch cables will function properly as long as both ends are wired using the same pinout standard.
Alice is working on an older network with a Windows Internet Name Service (WINS) server, a Domain Name System (DNS) server, and an Internet router. A user is complaining that he suddenly can't connect to hosts on other internal networks. The user isn't having problems connecting to resources on his local network or the Internet. Alice asks the user whether anything is new or has been changed on the computer and discovers that he recently changed some Internet Protocol (IP) parameters. What should Alice do next?
Verify that the user's IP configuration settings are correct. Since only one user is reporting the problem, the user's computer is the likeliest source of the problem. The user has probably changed or removed the WINS server address. If the user is working with an incorrect WINS address, he can access local network resources but not resources on another internal LAN. Also, he can access resources on the Internet, which means the Internet router and the DNS server are not the problem.
Ralph has been asked to create some new patch cables that will be used to connect patch panel ports to the network switches. He has been told to use the T568B pinout standard for all of the cable connectors. Ralph gathers the materials and the tools needed to complete the task, but he is not sure about the T568B pinout. Which of the following pinouts must Ralph use when creating the patch cables?
White/orange, orange, white/green, blue, white/blue, green, white/brown, brown.
Which of the following command-line utilities enables you to view the Internet Protocol (IP) configuration on a Unix or Linux host?
ifconfig On a Unix or Linux host, the ifconfig command displays the system's current IP configuration settings and parameters. ipconfig is a Windows command-line utility that performs the same basic function. The other options are command-line utilities that do not display IP configuration information.
Ralph is the administrator of his company's network. He has a Dynamic Host Configuration Protocol (DHCP) server configured to supply Internet Protocol (IP) addresses and configuration information to all of the Windows computers on the network. One of the Windows users reports that she cannot connect to the network. Which of the following commandscan Ralph run on her computer to verify the status of the computer's IP settings and configuration parameters?
ipconfig. ipconfig is a Windows command that displays a computer's current IP address and TCP/IP configuration settings, including whether the computer has obtained its address from a DHCP server. The ifconfig command displays the same information for Unix and Linux systems. Msinfo32 is a Windows program that generates a graphical display of the computer's hardware and software configuration, but not its IP address and TCP/IP settings. The tracert command in Windows displays the path that packets take through the internetwork to reach a specified destination, but it does not display DHCP information.
Which of the following commands can Ralph use to display the number of bytes that a Windows workstation has transmitted?
netstat Running netstat with the -e parameter on a Windows workstation displays Ethernet statistics, including the number of bytes and packets the workstation has sent and received. The ipconfig command displays TCP/IP configuration data; it does not display network traffic statistics. The tcpdump and iptables commands both run only on Unix and Linux workstations.
While performing a protocol analysis, Alice notes that there are many ICMP packets in her captured traffic samples. She attributes these to her frequent use of TCP/IP troubleshooting tools. Which of the following utilities are used to test network layer characteristics of a host using Internet Control Message Protocol (ICMP) messages? (Choose all correct answers.)
ping and tracert are both utilities that test network layer characteristics using ICMP messages. ping tests the network layer functionality of the host and traceroute displays the path to the host, through the internetwork. ipconfig and netstat do not use ICMP messages
