Network+ Domain 4: Troubleshooting, All Questions
Consider the 850 nm multimode fiber optic cable shown below. How much loss can you expect between the transmitter and the receiver? ----------------------- Connectors ----------------------- Transmiter <------ 200 meters ------> Receiver
-1.2 dB When calculating a loss budget for a segment of fiber optic cable, use the following guidelines: • Connectors = 0.3 dB loss each • Splices = 0.3 dB loss each • Multimode cabling = 3 dB loss per 1000 meters (850 nm) or 1 dB loss per 1000 meters (1300 nm) • Single mode cabling = 0.5 dB loss per 1000 meters (1310 nm) or 0.4 dB loss per 1000 meters (1550 nm) In this scenario, there are two connectors (0.3 dB loss each) and 200 meters of 850 nm multimode cable (.2 * 3 dB) for a total expected loss of 1.2 dB. Note that dirty or poorly polished connectors can dramatically increase the amount of loss in the cable.
Consider the following output from a dig command run on a Linux system. ; <<>> DiG 8.2 <<>> westsim111.com ;;res options:init recurs defnam dnsrch ;;got answer: ;;->>HEADER<<-opcode:QUERY, status: NOERROR, id:4 ;;flags: qr rd ra; QUERY:1, ANSWER:1, AUTHORITY:2, ADDITIONAL:0 ;;QUERY SECTION: ;; westsim111.com, type = A, class = IN ;;ANSWER SECTION: westsim111.com. 7h33m IN A 76.141.43.129 ;;AUTHORITY SECTION: westsim111.com. 7h33m IN NS dns1.deriatct111.com. westsim111.com. 7h33m IN NS dns2.deriatct222.com. ;;Total query time: 78 msec ;;FROM: localhost.localdomain to SERVER:default -- 202.64.49.150 ;;WHEN: Tue Feb 16 23:21:24 2005 ;;MSG SIZE sent: 30 rcvd:103 What is the IP address of the DNS server that performed this name resolution?
202.64.49.150
After installing a new 2.4Ghz cordless phone system in your office, you notice that wireless network performance is adversely affected. Which of the following wireless networking standards are you most likely to be using? (Select two.)
802.11b 802.11g
Review the output from the show interfaces fa0/1 command on the switch2 switch in the exhibit. What is wrong with the fa0/1 interface in this example?
A duplex mismatch exists with the device on the other end of the connection. In this example, the following statistics indicate that a duplex mismatch error has occurred: • Duplexing is set to half. • There are a significant number of runts. • There are a significant number of collisions. • There are a significant number of late collisions.
During a network infrastructure upgrade, you have replaced two 10 Mbps hubs with switches and upgraded from Category 3 UTP cable to Category 5e. During the process, you accidentally cut the Cat 5e patch cable that stretches from the network printer to the upgraded switch. What is the impact on the network?
All network nodes, with the exception of the printer, will be available.
You are creating an Ethernet network for your company. The shipping department is located in a different building that is located 150 meters from the main wiring closet. You connect a single Cat6e cable to connect the wiring closet to the shipping building. Which of the following conditions are you most likely to experience?
Attenuation Attenuation is the loss of signal strength from one end of a cable to the other. The longer the cable, the more attenuation. For this reason, it is important to not exceed the maximum cable length defined by the networking architecture. In this example, the distance from the wiring closet to the other building exceeds the 100 meter maximum for Ethernet.
You are troubleshooting a wireless connectivity issue in a small office. You determine that the 2.4GHz cordless phones used in the office are interfering with the wireless network transmissions. If the cordless phones are causing the interference, which of the following wireless standards could the network be using? (Select two.)
Bluetooth 802.11b
What must you install between your network and a T1 line for your network to use the T1 line?
CSU/DSU
Which of the following devices is used on a WAN to convert synchronous serial signals into digital signals?
CSU/DSU A CSU/DSU is a device that converts the signal received from the WAN provider into a signal that can be used by equipment at the customer site. A CSU/DSU is composed of two separate devices: • The CSU terminates the digital signal and provides error correction and line monitoring. • The DSU converts the digital data into synchronous serial data for connection to a router. The CSU/DSU might be two separate devices, one combined device, or it might be integrated into a router.
Consider the network shown in the exhibit. When you run the show interfaces command on switch1, you observe a significant number of runts on the Gi0/1 interface. What does this statistic indicate?
Collisions are occurring. Runts are frames that are too small. (The minimum frame size required is 64 bytes.) This is commonly caused by collisions. In this scenario, the collisions are probably caused by a duplex mismatch error.
Match each wireless term or concept on the left with its associated description on the right. Each term may be used more than once; not all descriptions have a matching term.
Compares the level of the WiFi signal to the level of background radio signals. ==> Signal to Noise Ratio Checks channel utilization and identifies sources of RF inference. ==> Spectrum analysis Identifies how strong a radio signal is at the receiver. ==> Received Signal Level Identifies the number of useful bits delivered from the sender to the receiver. ==> Leave Blank Causes multiple copies of the same radio signal to be received by the receiving antenna. ==> Bounce Degrades wireless network performance. ==> Device saturation
A user reports that she can't connect to the Internet. After some investigation, you find that the wireless router has been misconfigured. You are responsible for managing and maintaining the wireless access point. What should you do next?
Create an action plan.
You have decided to implement Gigabit Ethernet on your network. Each switch port is connected to a single device. Following the installation, you find one device connected to a switch that is only running at 100 Mbps. Which of the following are likely causes?
Crosstalk Crosstalk is interference that is caused by signals within the twisted pairs of wires. For example, current flow on one wire causes a current flow on a different wire. Crosstalk and other miswiring problems typically mean that a cable does not operate at the desired standard. Use a cable certifier to verify that that cable is properly configured to support the rated speed.
You have just connected a new computer to your network. The network uses static IP addressing. You find that the computer can communicate with hosts on the same subnet, but not with hosts on a different subnet. No other computers are having a problem. Which of the configuration values would you most likely need to change?
Default gateway
Users report that the network is down. After some investigation, you determine that a specific router is configured such that a routing loop exists. What should you do next?
Determine if escalation is needed.
A user reports that she can't connect to a server on your network. You check the problem and find out that all users are having the same problem. What should you do next?
Determine what has changed.
A user reports that network access from her workstation is very slow. The problem does not seem to be affecting any other users. Which of the following conditions is the most likely cause?
Duplex mismatch
You are troubleshooting a client connectivity problem on an Ethernet network. The client system has intermittent connectivity to the network. You discover that the UTP patch cable is run 75 feet from the wall outlet, passes though the ceiling and over several florescent light fixtures before reaching the client system. Which of the following may be a cause of the connectivity problem?
EMI interference
You are reviewing the output of the show interfaces command for the Gi0/1 interface on a switch. You notice a significant number of CRC errors displayed. What are the most likely causes? (Select two. Either response is a complete solution.)
EMI or cross-talk on the cable connected to the interface Collisions
You have a cable Internet connection at home. The installer had connected the router near the outside wall of your house with RG-6 cable. You move the cable router a distance of 50 meters using RG-8 cables and special connector adapters. Which condition are you most likely to experience?
Echo An impedance mismatch (manifested by echo) occurs when you connect cables and devices that have a different impedance (resistance) rating. Impedance is mostly a factor in coaxial cables used for networking. Be sure to choose cable with the correct rating (50 or 75 ohm) based on the network type, and do not mix cables with different ratings. RG-6 cables have a rating of 75 ohms, while RG-8 cables have a rating of 50 ohms.
You have configured a remote access server to accept dial-up connections for remote access clients. Remote clients are able to connect successfully and access resources on the remote access server. However, the remote clients are not able to connect to other devices located on the same subnet where the remote access server is located. Which action would likely correct the problem?
Enable proxy arp on the LAN connection for the remote access server.
You are a network administrator for your company. A frantic user calls you one morning exclaiming that "nothing is working." What should you do next in your troubleshooting strategy?
Establish the symptoms.
You have just connected four new computer systems to an Ethernet switch using spare patch cables. After the installation only three systems are able to access the network. You verify all client network settings and replace the network card in the failed system. The client is still unable to access the network. Which of the following might you suspect as the real cause of the problem?
Failed patch cable
You are moving a client to a new location within an Ethernet network. Previous to the move, the client system did not have difficulty accessing the network. During the relocation, you attach a patch cable from the client system to the wall jack and from the patch panel to the switch. Once connected you do not get a link light on the network card or the switch. You swap out the cable running between the patch panel and the switch with a known working one but you can still not connect. Which of the following might you suspect as the problem?
Failed patch cable between the client system and the wall jack
Upon conducting a visual inspection of the server room, you see that a switch displays LED collision lights that are continually lit. You check the LED on the corresponding workstation and see that it is flashing rapidly even though it is not sending or receiving network traffic at that time. What is the cause of the network collisions?
Faulty network card
A router periodically goes offline. Once it goes offline, you find that a simple reboot puts the router back online. After doing some research you find that the most likely cause of the problem is a bug in the router software. A new patch is available from the manufacturer that is supposed to eliminate the problem. What should you do next?
Identify possible effects of the solution.
A user reports that he can't connect to a specific website. You go to the user's computer and reproduce the problem. What should you do next?
Identify the affected areas of the network.
A user is unable to connect to the network. You investigate the problem and determine that the network adapter is defective. You replace the network adapter and verify that it works. What should you do next?
Identify the results and effects of the solution.
A user reports that he can't browse to a specific website on the Internet. From his computer, you find that a ping test to the web server succeeds. A traceroute test shows 17 hops to the destination web server. What is the most likely cause of the problem?
Incorrect DNS server address
You manage a local area network with several switches. A new employee has started today so you connect her workstation to a switch port. After connecting the workstation, you find that the workstation cannot get an IP address from the DHCP server. You check the link and status lights and the connection is working properly. A ping to the loopback address on the workstation succeeds. No other computers seem to have the problem. Which of the following is the most likely cause of the problem?
Incorrect VLAN assignment
You manage a network that has multiple internal subnets. You connect a workstation to the 192.168.1.0/24 subnet. This workstation can communicate with some hosts on the private network, but not with other hosts. You run ipconfig /all and see the following: Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : mydomain.local Description . . . . . . . : Broadcom network adapter Physical Address. . . . . . : 00-AA-BB-CC-74-EF DHCP Enabled . . . . . . . : No Autoconfiguration Enabled. . . : Yes IPv4 Address . . . . . . . : 192.168.1.102(Preferred) Subnet Mask. . . . . . . . : 255.255.0.0 Default Gateway . . . . . . : 192.168.1.1 DNS Servers . . . . . . . : 192.168.1.20 192.168.1.27 What is the most likely cause of the problem?
Incorrect subnet mask In this example, the network is using a mask of 255.255.255.0 (24-bits), but the workstation is configured to use a mask of 255.255.0.0.
Match each type of access point on the left with the wireless network architecture that they are commonly used in on the right. Each type of access point may be used once, more than once, or not at all.
Independent access point infrastructure ==> Intelligent AP Hub-and-spoke infrastructure ==> Lightweight AP Distributed wireless mesh infrastructure ==> Intelligent AP Independent access points: In the early days of wireless networking, large organization implemented independent access points through their facility. Each AP stood alone, providing separate wireless networks using its own independent configuration. Hub-and-spoke infrastructure: In a hub-and-spoke configuration, a wireless controller is connected to all access points using wired links. The individual access points contain very little embedded intelligence and are sometimes referred to as lightweight access points (LWAPs). Distributed wireless mesh infrastructure: Newer wireless networks can be deployed using a distributed wireless mesh architecture. These networks still use a controller, but they move some of the network intelligence from the controller out to the individual access points. In this configuration, the controller is no longer a bottleneck. The APs are smart enough to communicate directly with each other to create more efficient data paths for network traffic.
Users are complaining that sometimes network communications are slow. You use a protocol analyzer and find that packets are being corrupted as they pass through a switch. You also notice that this only seems to happen when the elevator is running. What should you do?
Install shielded cables near the elevator
You are reviewing the output of the show interfaces command for the Gi0/1 interface on a switch. Which interface statistic displays the number of collisions that occurred after the 64th byte of the frame was transmitted?
Late collisions
You are troubleshooting an IP addressing issue, and so issue a command to view the TCP/IP configuration of the system. The command you use produces the following output: fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 inet6 fe80::2a0:83ff:fe30:57a%fxp0 prefixlen 64 scopeid 0x1 inet 192.168.1.235 netmask 0xfffffc00 broadcast 255.255.255.255 ether 00:a0:83:30:05:7a media: Ethernet autoselect (100baseTX ) status: active lo0: flags=8049 mtu 16384 inet6 ::1 prefixlen 128 inet6 fe80::1%lo0 prefixlen 64 scopeid 0x7 inet 127.0.0.1 netmask 0xff000000 Which of the following operating systems are you working on?
Linux The output shown is from the ifconfig command run on a Linux system. The equivalent command on Windows 98, Windows 2000, and Windows Server 2003 is ipconfig.
You have decided to conduct a business meeting at a local coffee shop. The coffee shop you chose has a wireless hotspot for its customers who want Internet access. You decide to check your e-mail before the meeting begins, but when you open the browser you cannot gain Internet access. Other customers are on the Internet and because you use a wireless connection at work, you are sure your laptops wireless adapter works. What is the likely cause of the problem?
Mismatched SSID
You want to measure the voltage, amps, and ohms of various devices. Which tool should you use?
Multimeter
Which of the following best describes the condition where a signal sent on one wire is received on another wire within the same connector?
NEXT Near end crosstalk (NEXT) is crosstalk measured on the same end as the transmitter. For example, when a signal is sent on one wire, near end crosstalk measures the interference on another wire at the same connector near the source of the original signal. Far end crosstalk (FEXT) is crosstalk measured on the opposite end from the transmitter. For example, when a signal is sent on one wire, far end crosstalk measures the interference on another wire at the opposite end from the source signal.
You are building a new network for a small startup financial services company. Security is paramount, so each organization within the company will have its own network segment separated by a router. However, funds are limited, and you have been asked to keep costs to a minimum. You have acquired a used fiber optic switch and want to use it to create a fiber optic backbone that interconnects all of the routers. You purchased several used multimode GBIC modules on eBay that you will install in each router to allow them to connect to the switch. Both the switch and the GBIC modules use MT-RJ connectors. You purchased several used 1 meter multimode patch cables from Amazon. However, when they arrived, you noticed that they use LC connectors. Fortunately, with some force, you found that you are able to get the LC connectors on the cables to lock into the MT-RJ connectors on the GBIC modules and on the switch. Will this implementation work?
No, you should purchase patch cables that use MT-RJ connectors.
You are building a new network for a small startup financial services company. Security is paramount, so each organization within the company will have its own network segment separated by a router. However, funds are limited, and you have been asked to keep costs to a minimum. You have acquired a used fiber optic switch and want to use it to create a fiber optic backbone that interconnects all of the routers. You purchased several used single mode GBIC modules on eBay that you will install in each router to allow them to connect to the switch. Both the switch and the GBIC modules use MT-RJ connectors. You connect each module to the switch with 1 meter multimode patch cables. Will this implementation work?
No, you shouldn't use multimode patch cables with single mode GBIC modules.
You are setting up a wireless hotspot in a local coffee shop. For best results, you want to disperse the radio signals evenly throughout the coffee shop. Which of the following types of antennas would you use on the AP to provide a 360-degree dispersed wave pattern?
Omni-directional
Two routers with the hostnames SLC and PROVO have been configured to connect using PPP with CHAP authentication through their BRI0 interfaces. Attempts to establish a session between the two routers fails. You check the running configuration on both routers and find the output shown below: hostname SLC enable password cisco username PROVO password vanilla ! ! interface Serial0 ip address 172.16.55.129 255.255.255.252 encapsulation ppp ppp authentication chap ! ! - remaining output omitted -- hostname PROVO enable password ccna username SLC password chocolate ! ! interface Serial0 ip address 172.16.55.130 255.255.255.252 encapsulation ppp ppp authentication chap ! ! - remaining output omitted -- What should you do to correct the problem?
On SLC, change the username password to chocolate.
You have been hired to troubleshoot a wireless connectivity issue for two separate networks located within a close proximity. Both networks use a WAP from the same manufacturer and all settings, with the exception of SSIDs, remain configured to the default. Which of the following might you suspect as the cause of the connectivity problems?
Overlapping channels
You want to be able to identify traffic that is being generated and sent through the network by a specific application running on a device. Which tool should you use?
Protocol analyzer Use a protocol analyzer (also called a packet sniffer) to examine network traffic. You can capture or filter packets from a specific device or that use a specific protocol.
You are implementing a wireless network inside a local office. You require a wireless link to connect a laptop in the administrator's office directly to a system in the sales department. In the default configuration, the wireless AP uses a 360-dispersed RF wave design. After installed, the signal between the two systems is weak as many obstacles interfere with the signal. Which of the following strategies could you try to increase signal strength?
Replace the Omni-directional antenna with a directional antenna
A user from the Sales department calls to report that he is experiencing problems connecting to the Sales file server. All users in the Sales department connect to the Sales server through a single Ethernet switch. No other users have reported problems connecting to the Sales server. Which of the following troubleshooting actions are you most likely to perform first?
Replace the network card in the user's computer
Mobile devices in your organization use the access points shown in the figure below to connect to your wireless network. Recently, a catastrophic early morning power surge occurred, followed by an outage that lasted longer than your backup equipment could supply temporary power. After you powered the equipment back on, everything initially appeared to work correctly. However, ever since this event, some mobile users report that wireless network connections sometimes get dropped or perform very poorly. What should you do? (Select two.)
Set the channel used by access point B to 8. Set access point B to use 802.11n wireless networking.
You use Cat5e twisted pair cable on your network. Cables are routed through walls and the ceiling. A user puts a screw in the wall to hang a picture and pierces the cable such that a signal sent on pin 1 arrives on the cable connected to pin 7. What term describes this condition?
Short circuit An electrical short occurs when electrical signals take a different path other than the intended path. In the case of twisted pair wiring, a short means that a signal sent on one wire might arrive on a different wire. Shorts are caused by worn wire jackets or crushed wires so that two wires touch, or by something metal piercing the wire and causing an alternate path. An open circuit is a cut in the wire that prevents the original signal from reaching the end of the wire. With a short, the signal travels a different path, but with an open circuit, the signal does not travel anywhere (electricity cannot flow because the path is disconnected).
Users report that the Internet is no longer accessible. You suspect that the line connecting your building to the Internet is not working properly. Which of the following allows the service provider to remotely test the local loop?
Smart jack A smart jack is a special loopback plug installed at the demarcation point for a WAN service. Technicians at the central office can send diagnostic commands to the smart plug to test connectivity between the central office and the demarc. A smart jack is similar to a loopback plug; however, the loopback plug must be manually inserted into a jack to test the line, while the smart jack is a special plug that includes loopback support and can be used for remote testing of the local loop. With a smart jack, technicians can diagnose the local loop without visiting your location.
One method of preventing routing loops is to not send information about a route back to the router from which the information came. What is this technique called?
Split horizon Split horizon is a technique used by distance vector routing protocols that prevents routing loops by making sure that a router cannot send network information backwards. If Router1 receives routing information from Router2, it cannot send that same information back to Router2.
When troubleshooting network issues, it's important to carry out tasks in a specific order. Drag the trouble shooting task on the left to the correct step on the right.
Step 1- Identify the problem. Step 2 - Establish a theory of probable cause. Step 3 - Test the theory to determine the cause. Step 4 - Establish a plan of action. Step 5 - Implement the solution or escalate. Step 6 - Verify full system functionality. Step 7 - Document findings, actions and outcomes.
You are a network administrator for your company. A user calls and tells you that after stepping on the network cable in her office, that she can no longer access the network. You go to the office and see that one of the user's stiletto heels has broken and exposed some of the wires in the Cat 5 network cable. You make another cable and attach it from the wall plate to the user's computer. What should you do next in your troubleshooting strategy?
Test the solution.
Match each troubleshooting command on the left with its function on the right. Each utility may be used once, more than once, or not at all.
Tests connectivity between two network hosts by sending IPv4 ICMP Echo Request packets without modifying the TTL parameter. ==> ping Computes lost/sent packet statistics for each hop in the route between two hosts. ==> pathping Used on Linux systems to identify the route between two IPv6 hosts. ==> traceroute6 Used on Windows systems to identify the route between two IPv4 hosts. ==> tracert Tests connectivity between two network hosts by sending IPv6 ICMP Echo Request packets without modifying the TTL parameter. ==> ping -6
Your organization recently opened a branch office. You contracted with a WAN service provider to connect the branch office network to your home office network. Recently, your CEO conducted a video conference with the employees at the branch office. The employees complained that the video was choppy and that the audio was frequently out of sync with the video. What is the most likely cause of this poor WAN performance?
The WAN provider is throttling bandwidth on the link. In this scenario, its possible that the WAN service provider is the cause of the problem. You should check the contract with the service provider to make sure they aren't throttling the bandwidth of the WAN link. It's not uncommon for service providers to impose bandwidth or utilization caps that could be hampering communications. Because connectivity exists between the home and branch office networks in this scenario, the following are very unlikely to be the cause of the problem: • A disabled WAN interface • A protocol mismatch • An authentication mismatch • An IP address misconfiguration
A user on your network has been moved to another office down the hall. After the move she calls you complaining that she has only occasional network access through her wireless connection. Which of the following is most likely the cause of the problem?
The client system has moved too far away from the access point.
Consider the network shown in the exhibit. You have been experiencing intermittent connectivity issues with switch2. To check the status of the interfaces, you run the following commands: switch2# show interfaces fa0/1 status Port Name Status Vlan Duplex Speed Type Fa0/1 connected 3 a-half a-100 10/100BaseTX switch2# show interfaces Gi0/1 status Port Name Status Vlan Duplex Speed Type Gi0/1 connected trunk a-full a-1000 1000BaseTX switch2# show interfaces Gi0/2 status Port Name Status Vlan Duplex Speed Type Gi0/2 connected trunk a-full a-1000 1000BaseTX What is the issue with this network?
The device connected to the Fa0/1 interface has autonegotiation disabled. A duplex mismatch probably exists on the Fa0/1 interface. Note that duplexing has been automatically set to half, which is the default behavior for Cisco devices when autonegotiation fails. To fix the issue, check the Gi0/1 interface on router1 to see if autonegotiation has been disabled. You could manually configure the Fa0/1 interface on switch2 to use the same duplexing and link speed settings as the interface on the router, or you could re-enable autonegotiation on the router interface. The Gi0/1 and Gi0/2 interfaces on switch2 appear to be functioning correctly with full duplexing and full link speed having been automatically configured.
A workstation is connected to a switch on the Gi 0/2 interface using a straight-through cable. The Ethernet interface in the workstation has been manually configured to use a 100 Mbps link speed in full-duplex mode. Which of the following are true in this scenario? (Select three.)
The switch attempts to sense the link speed. If it can't, the slowest link speed supported on the interface is selected. If the link speed is 10 Mbps or 100 Mbps, half-duplex is used. If the link speed is 1000 Mbps or faster, full-duplex is used.
A user calls to report that she is experiencing intermittent problems while accessing the wireless network from her laptop computer. While talking to her, you discover that she is trying to work from the coffee room two floors above the floor where she normally works. What is the most likely cause of her connectivity problem?
The user is out of the effective range of the wireless access point on her floor.
Your organization uses an 802.11b wireless network. Recently, other tenants installed the following equipment in your building: • A wireless television distribution system running at 2.4 GHz • A wireless phone system running at 5.8 GHz • A wireless phone system running at 900 MHz • An 802.11a wireless network running in the 5.725 - 5.850 GHz frequency range • An 802.11j wireless network running in the 4.9 - 5.0 GHz frequency range Since this equipment was installed, your wireless network has been experiencing significant interference. Which system is to blame?
The wireless TV system
Your organization recently opened a branch office. You contracted with a WAN service provider to connect the branch office network to your home office network. This morning, users at the branch office reported that they can no longer access resources on the home office network. You ran the show interfaces command on the router at the home office and had an administrative assistant run the same command on the router at the branch office. Both routers reported the following: • Interface status: Up • Protocol status: Down What is the most likely cause of this WAN issue?
There is a data link encapsulation protocol mismatch between the WAN interfaces on both ends of the link. If the WAN interface's line status is up and the protocol status is down, then you're most likely experiencing a Layer 2 issue. This could be caused by a mismatch in the data link encapsulation protocol used on the link. Common Layer 2 point-to-point WAN protocols include HDLC, PPP, and Frame Relay. The same Layer 2 protocol must be used on both ends of the link.
Your organization recently opened a branch office. You contracted with a WAN service provider to connect the branch office network to your home office network. This morning, users at the branch office reported that they can no longer access resources on the home office network. You ran the show interfaces command on the router at the home office and had an administrative assistant run the same command on the router at the branch office. Both routers reported the following: • Interface status: Down • Protocol status: Down What are the most likely causes of this WAN issue? (Select two.)
There is a problem with the service provider's network. The WAN interface on one or both routers has been disabled. Because both the line status and the protocol status of the WAN interface is down, you're most likely experiencing a Layer 1 issue. As such, you should start troubleshooting at Layer 1. In this scenario, it's possible that: • One or both WAN interfaces have been shut down (disabled). • There is an issue with the service provider's network. Because both interfaces have a status of down/down, the problem must lie at Layer 1. The following issues are Layer 2 or 3 issues: • A protocol mismatch • An authentication mismatch • An IP address misconfiguration Latency on the link would still allow communications to occur between the routers, but performance would be poor. If this were the case, the interface status of both link ends would be in an up/up state.
Your organization recently opened a branch office. You contracted with a WAN service provider to connect the branch office network to your home office network. This morning, users at the branch office reported that they can no longer access resources on the home office network. You ran the show interfaces command on the router at the home office and had an administrative assistant run the same command on the router at the branch office. Both routers reported the following: • Interface status: Up • Protocol status: Up What is the most likely cause of this WAN issue?
There is an IP address misconfiguration issue between the WAN interfaces on both ends of the link.
Your organization recently opened a branch office. You contracted with a WAN service provider to connect the branch office network to your home office network. This morning, users at the branch office reported that they can no longer access resources on the home office network. You ran the show interfaces command on the router at the home office and had an administrative assistant run the same command on the router at the branch office. Both routers reported the following: • Interface status: Up • Protocol status: Down What is the most likely cause of this WAN issue?
There is an authentication misconfiguration issue between the WAN interfaces on both ends of the link.
Your organization recently opened a branch office in a remote area. Because of its location, traditional WAN connectivity was not available, so you contracted with a satellite provider to connect the branch office network to your home office network. Recently, your CEO conducted a video conference with the employees at the branch office. The employees complained that the video was choppy and that the audio was frequently out of sync with the video. What is the most likely cause of this poor WAN performance?
There is latency on the WAN link. In this scenario, its very likely that the satellite link itself is the cause of the problem. Because the radio signals used by satellite links must travel thousands of miles into space and back, several milliseconds of latency are introduced. For some types of network communications, such as saving a file or sending an email, this latency is not a problem. However, for time-sensitive communications such as a video conference, the latency inherent in the satellite link can cause poor network performance.
You have a WAN link that connects two sites. The WAN link is supposed to provide 1.5 Mbps of bandwidth. You want to perform a test to see the actual bandwidth of the link. Which tool should you use?
Throughput tester
You are troubleshooting a connectivity problem in which one client system is unable to connect to a server. Both the server and client system are connected to the same Ethernet network switch. No other users have complained of a problem, and you suspect that faulty network cabling might be to blame. Which of the following troubleshooting steps are you most likely to perform first?
Use a cable tester to test the cable between the computer system and the network switch.
While configuring a new 802.11g wireless network, you discover another wireless network within range that uses the same channel ID that you intend to use. Which of the following strategies are you most likely to adopt in order to avoid a conflict between the networks?
Use a different Channel ID.
You have just been hired as a network administrator. A user has just changed offices and needs you to activate the network and telephone connections in his office. However, the wiring at the punch down block is labeled poorly and you are unable to tell which wires go to the user's office. What should you do?
Use a tone generator to locate the correct wiring
Which of the following tools would you use to view the MAC addresses associated with IP addresses that the local workstation has contacted recently?
arp
Which TCP/IP utility gives you the following output? Interface: 192.168.4.101 on Interface 0x3 Internet Address Physical Address Type 192.168.1.23 00-d1-b6-b7-c2-af dynamic
arp This output is displayed when you use the arp command to look at the ARP cache.
Which TCP/IP utility gives you the following output? Interface: 192.168.1.111 on Interface 0x2 Internet Address Physical Address Type 192.168.1.102 00-60-08-bd-62-5a dynamic 192.168.1.168 00-06-5b-1c-48-76 dynamic
arp -a The arp -a command shows the current entries in the computer's ARP cache.
Consider the following output. ;; res options: init recurs defnam dnsrch ;;got answer: ;;->>HEADER<<-opcode:QUERY, status; NOERROR,id:4 ;;flags: qr rd ra; QUERY:1, ANSWER:1, AUTHORITY:2, ADDITIONAL:0 ;;QUERY SECTION: ;; westsim111.com, type = A, class = IN ;;ANSWER SECTION: westsim111.com. 7h33m IN A 76.141.43.129 ;;AUTHORITY SECTION: westsim111.com. 7h33m IN NS dns1.deriatct111.com. westsim111.com. 7h33m IN NS dns2.deriatct222.com. ;;Total query time: 78 msec ;;FROM: localhost.localdomain to SERVER: default -- 202.64.49.150 ;;WHEN: Tue Feb 16 23:21:24 2005 ;;MSG SIZE sent: 30 rcvd: 103 Which of the following utilities produced this output?
dig The output shown is from the dig command run on a Linux system. Although nslookup and dig provide much the same information, this output can be identified as coming from dig because dig produces significantly more detail in its default usage.
You are troubleshooting a connectivity problem on a Linux server. You are able to connect to another system on the local network, but are not able to connect to a server on a remote network. You suspect that the default gateway information for the system may be configured incorrectly. Which of the following commands would you use to view the default gateway information on the Linux server?
ifconfig Use the ifconfig command on systems running Linux to view information on the TCP/IP configuration of network adapters. Use ipconfig and winipcfg to view network configuration information on Windows systems. Use the dig command on Linux and Unix systems to query Domain Name Service (DNS) servers.
You work in an office that uses Linux servers, NetWare servers, and Windows NT 4.0 servers. The network uses both the TCP/IP and IPX/SPX protocols. The Linux server is used as an FTP server. Today you have received several calls from people who are unable to contact the Linux server at its known IP address. You are sitting at the Linux server and want to check its IP address. Which command should you use?
ifconfig Use the ifconfig command to show the TCP/IP configuration for a Linux computer.
You want to be able to view the DNS server address that a computer is using. Which of the following utilities would you use? (Select two.)
ifconfig ipconfig Use the ipconfig command on Windows and ifconfig command on Linux to view the IP configuration for a device including the IP address, subnet mask, default gateway, and DNS server addresses used for a connection.
Which TCP/IP utility gives you the following output? Ethernet Adapter Local Area Connection: Connection-specific DNS Suffix . : testout.com IP Address. . . . . . . . . . . . . . . . . . . : 192.168.1.111 Subnet Mask . . . . . . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . . . . . : 192.168.1.1
ipconfig The ipconfig command shows the computer's TCP/IP configuration information. winipcfg also shows the TCP/IP configuration, but in a Windows graphical format.
You have been called in to troubleshoot a connectivity problem on a newly installed Windows Server 2003 system. The system is operating satisfactorily and is able to communicate with other systems on the local network. However it is unable to access any systems on other segments of the corporate network. You suspect that the default gateway parameter for the system has not been configured, or may be configured incorrectly. Which of the following utilities are you most likely to use to view the default gateway information for the system?
ipconfig Use the ipconfig utility to view the TCP/IP configuration of a Windows Server 2003 system. The information displayed by ipconfig includes default gateway information. Use winipcfg to view the TCP/IP configurations on earlier versions of Windows including Windows 98 and Me. It is not supported by Windows Server 2003. Use the ifconfig command to view the TCP/IP configuration on a Linux, Unix or Macintosh system. Use the netstat command to view statistics on TCP connections.
You administer a NetBIOS-based network that uses the TCP/IP protocol. You are trying to troubleshoot a computer that is unable to contact a server by its NetBIOS name. Which command can you use to check the connection?
nbtstat Use nbtstat to troubleshoot NetBIOS name resolution problems. The command shows which NetBIOS names the server uses, and which NetBIOS names the client knows about.
Which TCP/IP utility gives you the following output? Local Area Connection: Node IpAddress: [192.168.1.111] Scope Id: [ ] NetBios Remote Cache Name Table Name Type Host Address Life [sec] ------------------------------------------------------------------------ NTINE.ES <54> UNIQUE 192.168.1.23 395 NTINE <20> UNIQUE 192.168.1.23 45 AUDIO <00> UNIQUE 192.168.1.168 585
nbtstat -c nbtstat -c shows you the resolved NetBIOS name cache for a computer. In other words, these are the NetBIOS name-to-IP address mappings for known remote computers.
Examine the following output: Active Connections Proto Local Address Foreign Address State TCP SERVER1:1036 localhost:4832 TIME_WAIT TCP SERVER1:4798 localhost:1032 TIME_WAIT TCP SERVER1:1258 pool-141-150-16-231.mad.east.ttr:24076 CLOSE_WAIT TCP SERVER1:2150 cpe-66-67-225-118.roc.res.rr.com:14100 ESTABLISHED TCP SERVER1:268 C872c-032.cpe.net.cale.rers.com:46360 ESTABLISHED TCP SERVER1:2995 ip68-97-96-186.ok.ok.cox.net:23135 ESTABLISHED Which of the following utilities produced this output?
netstat The output shown is produced by the netstat command. netstat reports the TCP/IP ports open on the local system, as well as identifying the protocol and remote host connected to that port. This information can be very useful when looking for security weaknesses, as a TCP/IP port that is open to traffic unnecessarily represents a security risk.
Your computer is sharing information with a remote computer using the TCP/IP protocol. Suddenly, the connection stops working and appears to hang. Which command can you use to check the connection?
netstat Use the netstat command to check the status of a TCP connection.
Which TCP/IP utility gives you the following output? Active Connections Proto Local Address Foreign Address State TCP me:epmap me:0 LISTENING TCP me:1025 me:0 LISTENING UDP me:emap *:* UDP me:netbios-ns *:*
netstat -a netstat -a shows you the status of all connections and listening ports.
Which TCP/IP utility gives you the following output? Route Table ========================================== Interface List 0x1 . . . . . . . . . . . . . . MS TCP Loopback interface 0x2 . . .00 10 4b . . . 3 Com 3C90x Ethernet Adapter ========================================== ========================================== Active Routes:
netstat -r netstat -r shows you the computer's route table.
Which command displays network activity statistics for TCP, UDP, and IP?
netstat -s Netstat -s displays network activity statistics for TCP, UDP, and IP.
Examine the following output: Server: helicuplar.xct.takro.net Address: 209.53.4.130 Name: westsim.com Address: 64.78.193.84 Which of the following utilities produced this output?
nslookup The output is from the nslookup command on a Windows Server 2003 system. nslookup is a tool that allows you to send manual DNS resolution requests to a DNS server. The output displays the IP address and hostname of the DNS server that performed the resolution, and the IP address and hostname of the target specified for resolution. nslookup can be a useful tool when troubleshooting DNS name resolution problems.
Mary calls to tell you that she can't connect to an intranet server called WebSrv1. From her computer, you ping the server's IP address. The ping test is successful. Which tool would you use on her workstation next to troubleshoot the problem?
nslookup Use nslookup to troubleshoot name resolution problems. Because the ping test was successful, you know that both the client and the server can communicate using TCP/IP with IP addresses. This tells you that the problem is related to name resolution.
You are troubleshooting a network connectivity issue on a Unix system. You are able to connect to remote systems by using their IP address, but unable to connect using the hostname. You check the TCP/IP configuration, and note that a DNS server IP address is configured. You decide to run some manual resolution queries to ensure that the communication between the Unix system and the DNS server are working correctly. Which utilities can you use to do this? (Choose two.)
nslookup dig The dig and nslookup commands allow you to perform manual DNS lookups from a Linux or Unix system. This can be very useful when troubleshooting name resolution issues.
You need to perform a reverse lookup of the 10.0.0.3 IP address. Which command can you use to accomplish this? (Select two. Each response is a complete solution.)
nslookup 10.0.0.3 dig -x 10.0.0.3
You work in an office that uses NetWare servers and Windows NT 4.0 servers. The network uses both the TCP/IP and IPX/SPX protocols. You are sitting at a workstation that uses Windows 95 OSR2. An application you are using is unable to contact a Windows NT server named FileSrv2. Which command can you use to determine whether your computer can still contact the server?
ping
Which TCP/IP utility gives you the following output? Reply from 192.168.1.168: bytes=32 time<10ms TTL=128> Reply from 192.168.1.168: bytes=32 time<10ms TTL=128> Reply from 192.168.1.168: bytes=32 time<10ms TTL=128> Reply from 192.168.1.168: bytes=32 time<10ms TTL=128> Packets: Sent = 4, Received = 4, Lost = 0 <0% Loss>, Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms
ping The output of the ping command shows you the results of four echo request/reply contacts with a destination host.
Examine the following output. Reply from 64.78.193.84: bytes=32 time=86ms TTL=115 Reply from 64.78.193.84: bytes=32 time=43ms TTL=115 Reply from 64.78.193.84: bytes=32 time=44ms TTL=115 Reply from 64.78.193.84: bytes=32 time=47ms TTL=115 Reply from 64.78.193.84: bytes=32 time=44ms TTL=115 Reply from 64.78.193.84: bytes=32 time=44ms TTL=115 Reply from 64.78.193.84: bytes=32 time=73ms TTL=115 Reply from 64.78.193.84: bytes=32 time=46ms TTL=115 Which of the following utilities produced this output?
ping The output shown was produced by the ping utility. Specifically, the information output was created using theping -t command. The -t switch causes packets to be sent to the remote host continuously until stopped manually. ping is a useful tool for testing connectivity between devices on a network. Using the -t switch with ping can be useful in determining whether the network is congested, as such a condition will cause sporadic failures in the ping stream. tracert is similar to ping in that it tests connectivity between two hosts on the network. The difference is that tracert reports information on all intermediate devices between the host system and the target system. ping, on the other hand, does not report information on intermediate devices.
Which of the following utilities would you use to view the routing table?
route Use the route command to display the contents of the routing table or to add or remove static routes. traceroute or tracert uses ICMP packets to test connectivity between devices, and shows the path between the two devices. Responses from each hop on the route are measured three times to provide an accurate representation of how long the packet takes to reach, and be returned by that host. The mtr command on Linux is a combination of the ping and traceroute commands.
Which of the following commands would display the output shown here? Route Table ========================================== Interface List 0x1 . . . . . . . . . . . . . . MS TCP Loopback interface 0x2 . . .00 10 4b . . . 3 Com 3C90x Ethernet Adapter ========================================== ========================================== Active Routes:
route print Use the route print or netstat -r commands to display the contents of the routing table.
You are troubleshooting physical layer issues with the Gi0/1 interface in a router. You need to view and analyze the number of collisions detected on the interface. Which command should you use?
show interfaces gi0/1
You are troubleshooting physical layer issues with the Gi0/1 interface in a router. You suspect that a duplex mismatch error has occurred, and you need to determine the duplex settings configured on the interface. Which commands could you use? (Choose two. Each response is a complete solution.)
show interfaces gi0/1 show interfaces gi0/1 status
While troubleshooting a problem on a Linux system, you run a utility that generates the following output: 5 s3232.gw.Seat.someisp.net (63.201.72.9) 38.433 ms 38.713 ms 39.085 ms 6 st11122.gar1.Seat.someisp.net (211.242.9.121) 38.620 ms 38.593 ms 38.050 ms 7 oc48-6yy.Seat.someisp.net (14.248.154.129) 57.440 ms 56.678 ms 57.675 ms 8 t223hgh-ytry.swa.someisp.net (142.133.89.232) 103.041 ms 57.181 ms 56.619 ms 9 t8343mmd.cgssel.someisp.net (162.191.10261) 91.977 ms 93.971 ms 93.767 ms 10 twirem2.cgssfdl.ip.someisp.net (145.97.133.23) 92.463 ms 92.337 ms 93.523 ms 11 twerrm1.nfffsiny.ip.someisp.net (117.116.141.38) 106.000 ms 106.007 ms 105.283 ms 12 gbed22repp0.n5ddsdsy.ip.someisp.net (123.194.132.8) 103.198 ms 105.447 ms 104.263 ms Which of the following utilities were you using?
traceroute The output from traceroute and tracert are very similar. However, tracert is a utility used on Windows systems, not on Linux systems. As the question stated that you were working on a Linux system, the output would therefore be from traceroute. Use the dig command on Unix to troubleshoot DNS issues. Use ping to test connectivity between systems on a network.
While working on a Linux server, you are unable to connect to Windows Server 2003 system across the Internet. You are able to ping the default gateway on your own network, so you suspect that the problem lies outside of the local network. Which utility would you use to track the route a packet takes as it crosses the network?
traceroute traceroute is a Linux utility that allows you to track the route of a packet as it traverses the network. The traceroute utility is used on Linux systems, while tracert is used on Windows systems.
Which TCP/IP utility gives you the following output? 2 14 ms <10 ms 14 ms Loopback0.GW1.ALTER.NET [137.39.2.123] 3 14 ms <10 ms 13 ms 122.at.-6-0.SLT4.ALTER.NET [152.63.91.86] 4 <10 ms 14 ms 10 ms 0.so.-0-1-0.ALTER.NET [152.63.1.210]
tracert The exhibit shows a few lines from the tracert command, which shows you each host a packet must pass through to reach its destination.
Examine the following output: 4 22 ms 21 ms 22 ms sttlwa01gr02.bb.ispxy.com [154.11.10.62] 5 39 ms 39 ms 65 ms plalca01gr00.bb.ispxy.com [154.11.12.11] 6 39 ms 39 ms 39 ms Rwest.plalca01gr00.bb.ispxy.com [154.11.3.14] 7 40 ms 39 ms 46 ms svl-core-03.inet.ispxy.net [205.171.205.29] 8 75 ms 117 ms 63 ms dia-core-01.inet.ispxy.net [205.171.142.1] Which of these commands produced this output?
tracert The output is from a tracert command run on a Windows Server 2003 system. The tracert command provides information on each step in the route a packet takes to reach a remote host. Responses from each hop on the route are measured three times to provide an accurate representation of how long the packet takes to reach, and be returned by that host. This information can be useful in locating congestion points on a network, or when verifying that network routing is operating as expected.
You are the network administrator of a branch office of your company. The branch office network is part of a WAN that covers most of the United States. The office has two Windows 2000 servers, two UNIX servers, one Windows NT server, 90 Windows 98 clients, 40 Windows 2000 Professional clients, and five Macintosh clients. Users have been complaining that they are unable to access resources over the WAN at the main headquarters. You suspect that one of the routers between your office and the main headquarters is not working properly. What TCP/IP utility can you use to see if a router is not working properly?
tracert tracert shows you the series of routers that are used between the source and destination computers. If a router is not functioning, tracert can help you find which router is not working by showing you the last router it was successfully able to contact.
