5.0 Network Trouble Shooting Flashcards
You need to increase the area that is covered by your wireless network to include another building. You decide to use a signal bounce. All of the following could help with this issue EXCEPT:
A) repeaters
B) channel bonding
C) reflectors
D) encryption
Encryption cannot increase the area covered by your wireless network. Encryption is a security feature that protects data that is transmitted over the wireless network. Encryption when used on a wireless network can be used to prevent messages from being intercepted and read. However, you must ensure that the encryption methods used are compatible. Incompatible encryption methods would cause communication between the wireless networks or between the wireless and wired networks.
Repeaters, reflectors, and channel bonding can increase the area covered by your wireless network by using a signal bounce. Repeaters and reflectors simply bounce the signal. Channel bonding is an 802.11n implementation that increases the bandwidth by combining two adjacent 20-MHz bands.
Keep in mind that wireless switch or access placement is also important. Often just relocating an access point can alter the covered area enough to include the new location. Another factor is the signal strength. Signal strength can be adjusted based on your organization’s needs. Signal strength is also referred to as power level. Remember that using signal bounce can make the signal strength at a device appear as a strong signal with the user still experiencing consistent drops issues.
What happens when wireless access point is at full capacity with devices?
Device saturation − Some wireless networks support a maximum number of devices. Once device saturation occurs, no other devices will be able to join the network. You will need to deploy another wireless access point, upgrade the current access point to support more devices, or replace the current access point with one that will support more devices.
What occurs when there is too many devices that surpasses the maximum bandwidth of a Wireless Access Point?
Bandwidth saturation − Wireless networks have a maximum bandwidth available. If too many devices connect to the wireless network and have high bandwidth requirements, bandwidth saturation can occur. If this occurs, you should determine which devices are requiring the most bandwidth and move them to another network. You could also deploy another wireless network with a higher bandwidth maximum.
What should you do when you update a wireless device?
Untested updates − Any updates to wireless network devices should be thoroughly tested before deployment on the network. This includes any firmware updates.
Why should you avoid open wireless networks?
Open networks − Open networks are commonly deployed in public areas, such as libraries, coffee shops, and retail establishments, to provide a service to customers. However, you should use extreme caution when using open, unsecured networks as any communication can be intercepted and read. Companies should adopt a policy that clearly states whether personnel can connect to open networks using company-issued devices, including laptops, cell phones, and other mobile devices.
What protocol should you follow when there is incompatibility?
Incompatibilities − Incompatibilities usually occur when you deploy a device, update, or application that is incompatible with the clients on your wireless network. It may be necessary to roll back the update, remove the application, or reconfigure the device. If you deploy devices, updates, or applications in a testing environment first, you should be able to discover these issues before live deployment.
What standard is MIMO uses on the IEEE?
Multiple in, multiple out (MIMO) − MIMO is deployed in 802.11n wireless networks. It uses separate antennas for outgoing and incoming transmissions. MIMO increases reliability and throughput.
What happens when there is RF Attenuation?
Radio Frequency (RF) Attenuation – RF attenuation is when RF or light waves have their signal strength weakened. This attenuation happens naturally as the signals pass through walls, bodies, windows, and similar surroundings. While this has become less of a problem with modern Wi-Fi networks, IT teams should keep this issue in mind when designing a network.
What happens when you use the wrong Encryption Protocol?
Encryption Protocol Mismatch – An encryption protocol mismatch occurs when a user uses a security key to unlock an encryption protocol, but that key does not work with the designated protocol. Protocol key management can be a cumbersome process, especially with networks that utilize several encrypting protocols. Implementing a key manager can be one way to ensure these mismatches do not occur often.
What do you do when you have a Captive portal Issues?
Captive Portal Issues – A captive portal is a web page that is accessed by a web browser to help authenticate and authorize users when they are first connecting to a network. However, this portal can have issues occur with authentication, redirection, broken rules, and other similar issues. Whenever implementing a captive portal, it is critical to test the portal to ensure that it is functioning properly and preventing unauthorized parties from entering the network.
What happens when Client Disassociation Issues arise?
Client Disassociation Issues – Disassociation occurs when a user is removed or disconnected from a network either from being forcibly removed or by a network error occurring. Disassociation can be disruptive to workflow as well as be an indicator of a potential attack taking place, such as an Evil Twin attack.
What are the AP Configurations?
Lightweight Access Point Protocol (LWAPP) − LWAPP is a protocol that allows a wireless LAN controller (WAC) to manage and control multiple wireless access points.
Control And Provisioning of Wireless Access Points (CAPWAP) is a newer alternative to LWAPP.
Thin vs thick − Thick access points handle a wide array of tasks in software, each a separate IP address wired directly into Ethernet switches, If WLAN controller is deployed, the access points no longer have to handle as many tasks because they can be handed off to the WLAN controller. When a WLAN controller is used, the APs are referred to as thin APs.
AP association time – Whenever connection to an access point within a network there are several steps that should take place. This process begins by a device requesting access, to which the AP going through the process to authenticate the user. After the user verifies their identity, then the user must make an association request to the AP. After receiving the association request, the AP will then create an Association ID for the device and give them access to the network. This entire process refers to how long the AP association time takes. Fast association times will enable users to connect faster and be more productive rather than having to wait for unspecified times for the AP to respond. Attackers can try to target these APs by flooding them with fake access requests to attempt to cause a denial-of-service attack, which will subsequently slow down workflow production.
You are a desktop administrator for Nutex Corporation. Your organization uses Ethernet cable to connect network resources. A user reports that he is unable to access network resources on his portable computer. The portable computer is connected to the company’s network using an Ethernet cable. When you test the cable using a time domain reflectometer (TDR), the signal returns too soon. What should you do?
A) Re-route the network cable.
B) Reinstall the network adapter.
C) Replace the network adapter.
D) Replace the network cable.
You should replace the network cable. As stated in the scenario, the TDR shows that signal returns too early, which implies that there is a breakage in the network cable. Therefore, you should replace the cable to fix the problem.
You should not reinstall the network adapter. The TDR shows that the signal returns too early which implies that there is a breakage in the network cable. Reinstalling the network adapter will not fix the problem. You should only reinstall the network adapter if you discover an issue with the adapter’s driver.
You should not replace the network adapter. This is required if Device Manager cannot detect a network adapter plugged in the computer or if the network adapter is faulty.
You should not re-route the network cable. This would be a problem if interference were occurring. Re-routing cable further from the interference source usually can fix the problem. Cables can also be enclosed in a protective shield to prevent interference. It is also necessary to re-route a network cable if it lies across the floor. Routing network cable across the floor can cause tripping hazards and can result in cable breakage from the constant pressure of being walked on.
A hacker has used a packet sniffer to attack your company’s network. What can a hacker accomplish by using this technique?
A) initiating a social engineering attack
B) spreading a virus on a network
C) collecting data on network traffic
D) inserting a Trojan horse on a network server
A packet sniffer is a device that can be used to collect traffic data on network media, even if the traffic is not addressed to that device. A packet sniffer is also called a network analyzer, network sniffer, or protocol analyzer. Many packet sniffers can provide in-depth traffic analysis for your network. An attacker can use a packet sniffer to defeat a MAC address filter. A packet sniffer is a type of network analyzer.
A hacker can initiate a social engineering attack by using several methods, such as instant messaging, a telephone call, or an in-person visit to a company. A virus can be spread through several methods, such as infected storage media or infected e-mail messages. A hacker can use e-mail or another transmission method to insert a Trojan horse on a network server.
Your organization has responded to a security incident. The breach has been contained, and all systems have been recovered. What should you do last as part of the incident response?
A) investigation
B) post-mortem review
C) analysis
D) triage
A post-mortem review should be completed last as part of the incident response. The post-mortem review should be performed within the first week of completing the investigation of the intrusion. Triage is part of the first step in an incident response. During this step, the incident response team examines the incident to see what was affected and sets priorities. Investigation takes place after the triage. It involved the collection of relevant data. After the investigation stage, the incident response team is responsible for the containment stage. After the incident is contained, the next stage is analysis, where the root cause of the incident is discovered.
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - First step:
- Identify the problem.
What does this entail?
a. Identify the problem.
b. Gather information.
c. Question users.
d. Identify symptoms.
e. Determine if anything has changed.
f. Duplicate the problem, if possible.
g. Approach multiple problems individually.
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - Second step:
- Establish a Theory
What does this entail?
a. Question the obvious.
b. Consider multiple approaches.
-Top-to-bottom/bottom-to-top OSI model
- Divide and conquer
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - Third Step:
3.Test the theory to determine cause.
What does this entail?
a. If the theory is confirmed, determine next steps to resolve the problem.
b. If the theory is not confirmed, re-establish new theory or escalate.
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - What is the 4th step?
Establish a plan of action to resolve the problem and identify potential effects,
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - What is the 5th step?
Implement the solution or escalate as necessary,
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - What is the 6th step?
Verify full system functionality and, if applicable, implement preventive measures.
The troubleshooting order according to the CompTIA Network+ blueprint is as follows - What is the 7th step?
Document findings, actions, outcomes, and lessons learned.
You need to create a cable that will allow you to get a link light on your network interface card (NIC) when the NIC is not plugged into a hub or switch. Which type of cable should you use?
A) crossover cable
B) rollover cable
C) loopback cable
D) straight-through cable
You should use a loopback cable. A loopback cable is used to test the network function of the NIC by allowing it to send and receive network communication with itself.
A crossover cable connects two legacy or non-MDIX compliant devices, such as two computers, two hubs, or two switches.
Are patch cables the same thing as straight through cables?
A patch cable and a straight-through cable are the same thing. This is the standard cable used to connect networking devices.
What are the pinout setting for a roll over cable?
A rollover cable connects the console port on any Cisco device. The pin configuration for a rollover cable is easy to remember because of the cable name. The cable pin configuration is “rolled over” so that pin 1 on end 1 is pin 8 on the other, pin 2 on end 1 is pin 7 on the other, and so on until a complete reversal is made. The wires are in reverse order on opposite ends.
You have two wireless networks in your building. The wireless networks do not overlap. Both of them use Wi-Fi Protected Access (WPA).
You want to ensure that no unauthorized wireless access points are established. What should you do?
A) Disable SSID broadcast for the two wireless networks.
B) Periodically complete a site survey.
C) Change the two wireless networks to WEP.
D) Change the two wireless networks to WPA2.
You should periodically complete a site survey to ensure that no unauthorized wireless access points are established. Site surveys generally produce information on the types of systems in use, the protocols in use, and other critical information. This information often comes in the form of an audit or assessment report. These reports can be useful in detailing information about the site, identify any abnormal devices or apps, and help track baselines over periods of time. You need to ensure that hackers cannot use site surveys to obtain this information.
The security administrator just updated some security settings, including settings on routers and firewall. Users are complaining that they cannot access certain remote resources that they were able to access prior to the changes being made. What is most likely the problem?
A) Incorrect ACL settings
B) Duplicate MAC addresses
C) Incorrect netmask
D) Incorrect time
You should check for incorrect access control list (ACL) settings. ACL settings allow or deny the transmission of network traffic (inbound or outbound). Incorrect settings could block traffic that was intended to be allowed.
What happens when you have detailed the wrong the subnet mask?
An incorrect netmask can cause routing and performance issues. In classless interdomain routing (CIDR) notation, the netmask follows the IP address, beginning with the slash. As an example, in the IP address 172.16.0.0/16, the netmask is /16. The netmask determines the subnet to which the IP address belongs and the size of the subnet. An incorrect subnet mask would prevent communication with the resources but is not the most likely problem. If an incorrect subnet mask was used, all users will have trouble communicating with the resource that is incorrectly configured.
What happens when you have a duplicate MAC address?
Duplicate MAC addresses can be caused by MAC address spoofing, static IP addresses still in the pool of available addresses, or by manufacturers reusing MAC addresses. It is not likely that the MAC addresses were changed in any way, as this is not a standard step to take. To resolve a duplicate address caused by a static address, turn off the client computer that has the static address, remove the static IP address from the pool on the DHCP server, and then restart the client computer. With regard to manufacturers recycling MAC addresses, as long as two NICs with the same MAC address have at least one router between them, there will not be a conflict. Routers direct traffic via IP addresses, while switches direct traffic via MAC addresses, with an ARP table showing the relationship between MAC address and IP address.
What is the ping used for?
ping − tests connectivity to a remote host
What is the ipconfig used for?
ipconfig − displays network configuration settings for the local computer
What is the nslookup used for?
nslookup − verifies entries on a DNS server
What is nbstat used for?
nbtstat − diagnoses problems with NetBIOS name resolution
Your company is located in Atlanta, Georgia. Management has decided to deploy multiple 802.11b WLANs. You are concerned that there are not enough non-overlapping channels to support the number of access points that you need to deploy. How many non-overlapping channels are supported in this deployment?
A) eight
B) eleven
C) three
D) five
802.11b wireless local area networks (WLANs) support three non-overlapping or non-interfering channels that can be used in a single area. An additional channel (channel 14) is supported in all countries except the United States.
Wireless access points or bridges must use non-adjacent, non-overlapping radio channels to prevent interference from the adjacent bridge or access point.
Each 802.11b channel utilizes a RF bandwidth of 22 MHz in DSSS modulation. You can use a combination of channels 1, 6, and 11 in a single area, referred to as a cell. This allows the 802.11b networks to provide a collective bandwidth of 33 Mbps in a cell for an office or home WLAN environment. When using multiple bridges to cover a large area, you should ensure that the channels are configured in such a way that there is no overlap.
A network contains 150 Windows client computers that all receive their IP configuration from a DHCP server. The network is divided into two subnets. The network administrator decides to move a client computer from one subnet to another. After moving the client, the computer is having trouble communicating on the network. You suspect that the client computer is using an IP address from the old subnet. You need to run the appropriate commands to ensure that the client computer receives a new IP address.
Select the appropriate command(s) from the left and place them in the appropriate order on the left. Only select commands that are necessary for the scenario. The scenario may include one or more commands. Order is important.
ipconfig /release
ipconfig /renew
ipconfig/ all
ipconfig/ flushdns
ipconfig/ displaydns
ipconfig/ showclassid
iconfig/ setclassid
For this scenario, you need to release and renew the DHCP lease for the client computer. You do this by running the following commands:
ipconfig /release
ipconfig /renew
The ipconfig /all command will display all the TCP/IP settings for the computers.
The ipconfig /flushdns command removes the contents of the computer’s DNS cache.
The ipconfig /registerdns command registers the computer’s DNS host name with the DNS server.
The ipconfig /displaydns command displays the contents of the computer’s DNS cache.
The ipconfig /showclassid command will display the DHCP class ID assigned to the client computer.
The ipconfig /setclassid command will configure the DHCP class ID for the client computer.
You should only select commands needed for the scenario. In some cases, only a single command may be necessary.
You want to configure a firewall and filter packets on a Linux system. Which command would you use?
A) nslookup
B) ifconfig
C) iptables
D) tcpdump
The iptables Linux command allows you to control a firewall and filter packets. Filtering can be performed using packet type, packet source/destination, or target.
The tcpdump command allows you to analyze wired or wireless network traffic on a Linux system. For example, to examine POP3 traffic on the wired NIC, you would use this command:
sudo tcpdump -I eth0 -nn -s0 -v port 110
what is ifconfig used for?
Ifconfig is the counterpart to the Windows ipconfig command, and provides information about the network interface card. Ifconfig functions much the same way as ipconfig, but it does not provide information on wireless adapters. To retrieve information about wireless adapters on a non-Windows system, use the iwconfig command.
You have implemented a new 802.11b 2.4-GHz WLAN. Which of the following devices can cause interference with this network? (Choose 2)
A) electrical wiring
B) cordless phones
C) cable TV cabling
D) microwave ovens
Microwave ovens can cause interference for 802.11b wireless local area networks (WLANs) that operate in the 2.4-GHz frequency band. Microwave ovens operate at the 2.45-GHz frequency band, and can cause interference when used in areas where 802.11b WLANs are deployed. Cordless phones can also cause interference. Typically these cordless phones use a higher transmitting power than the access points and can create a lot of noise in 802.11b WLANs. To avoid the interference from cordless phones, you can change either the location of access points or the location of the cordless phones. You can use the cordless phones that operate at 900MHz frequency band to avoid interference with 802.11b WLANs. Most medical equipment that uses radio frequencies operates in the 2.4-GHz ISM frequency band. Therefore, when doing a site survey, you must consider the interference by microwave ovens, cordless phones, and other devices that operate in the 2.4-GHz ISM frequency band, and you should plan the positions of the access points according to these devices to avoid interference.
You need to obtain the current protocol statistics and port connections for Windows and UNIX/Linux computers. Which tool should you use?
A) tracert
B) netstat
C) nbtstat
D) ping
Netstat is a TCP/IP utility that you can use to determine the computer’s inbound and outbound TCP/IP connections. It displays current connections and their listening ports.
What is tracert used for?
Issuing tracert at a Windows command prompt will trace the route a packet takes from the source computer to the destination host.
The network administrator has changed the IP address of several servers on the network. Now a user named Jim is unable to connect to file shares on those servers using the computer name. You need to run the appropriate command(s) on Jim’s computer to resolve the problem.
Select the appropriate command(s) from the left and place them in the appropriate order on the left. Only select commands that are necessary for the scenario. The scenario may include one or more commands. Order is important.
ipconfig /release
ipconfig /renew
ipconfig/ all
ipconfig/ flushdns
ipconfig/ displaydns
ipconfig/ showclassid
iconfig/ setclassid
All you need to do is flush the contents of the client computer’s DNS cache. You do this by running the following command:
ipconfig /flushdns
The ipconfig /all command will display all the TCP/IP settings for the computers.
The ipconfig /registerdns command registers the computer’s DNS host name with the DNS server.
The ipconfig /displaydns command displays the contents of the computer’s DNS cache.
The ipconfig /renew command will renew the client’s DHCP lease.
The ipconfig /release command will release the client’s DHCP lease.
The ipconfig /showclassid command will display the DHCP class ID assigned to the client computer.
The ipconfig /setclassid command will configure the DHCP class ID for the client computer.
You need to perform some administrative maintenance on a Cisco router. You decide to connect your notebook computer to the console port on the router. Which type of cable should you use?
A) crossover cable
B) patch cable
C) rollover cable
D) straight-through cable
You should use a rollover cable (also called a console cable) to connect to the console port on any Cisco device. The pin configuration for a rollover cable is easy to remember because of the cable’s name. The cable pin configuration is “rolled over” so that pin 1 on end 1 matches pin 8 on end 2, pin 2 on end 1 matches pin 7 on end 2, and so on, until a complete reversal is made. In other words, the wires are in reverse order on opposite ends.
You have been hired as a network consultant by a company. You discover that the network’s signal strength greatly weakens as traffic travels over the network medium due to absorption and scattering. What is the term for this tendency?
A) Refraction
B) Attenuation
C) EMI
D) Harmonic distortion
E) Intermodulation distortion
In networking, attenuation is the term for a loss of signal strength as data travels over the network medium (cable). The attenuation rate is often the deciding factor when selecting the medium to use for a particular length of network cable. Attenuation is also referred to a decibel (Db) loss.
For example, unshielded twisted-pair (UTP) cable has the greatest susceptibility to attenuation. This is why the maximum recommended segment length for UTP is limited to 100 meters (328 feet). ThinNet cable, on the other hand, has less susceptibility to attenuation; the signal can travel a distance of 185 meters (607 feet) before being adversely affected by attenuation.
What is a crossover cable?
A crossover cable connects two legacy or non-MDIX compliant devices, such as two computers, two hubs, or two switches.
What is the opposite of attenuation?
The opposite of attenuation is amplification. If you want to create a network that extends beyond the normally acceptable length of a particular cable type, you would need to install a signal amplifier. In networking terms, this amplifier is called a “repeater.”
What occurs when fluorescent lighting and Radio frequency interfere with?
Electromagnetic interference (EMI) occurs when objects, such as fluorescent lighting, interfere with transmission over copper cabling. Radio frequency interference (RFI) occurs when objects, such as cordless phones, interfere with transmission over wireless radio frequencies.
When does Crosstalk happen?
Crosstalk is a specialized type of EMI caused by parallel runs of twisted-pair cables. The only solution to this problem is to change the path of the cables.
What types of Cross talk are there?
Near end − Near-end crosstalk (NEXT) measures the ability of the cable to resist crosstalk. Most commercial cabling will give you the minimum NEXT values that are guaranteed.
Far end − Far-end crosstalk (FEXT) measures interference between two pairs of a cable measured at the other end of the cable with respect to the interfering transmitter.
EMI affects cable placement. You should arrange cables to minimize interference. Ideally, Ethernet cables should not be placed close to high voltage cables, generators, motors, or radio transmitters.
What is Refraction?
Refraction is the bending of waves as they pass from one medium to another, due to a change in their speed. Harmonic distortion is the distortion of a wave by unwanted multiples of an original frequency, causing interruptions to the way the wave form behaves in electrical circuits, or sounds. Intermodulation distortion occurs when two different frequencies are simultaneously passed through an amplifier
You are a system administrator. A user calls you complaining that he cannot log on to the network. What are two questions you should ask first when troubleshooting the problem? (Choose 2)
A) Can the problem be duplicated?
B) Are other users also experiencing the same problem?
C) Is the computer plugged in?
D) How much memory does your computer have?
One of the first steps in troubleshooting is to isolate the source of the problem. By asking if other users are experiencing the same problem, you will know if this is a network problem or a problem with the user’s logon process. If the problem cannot be duplicated, it could be an intermittent problem, or it could be something simple, such as the user typing his password incorrectly. Determining the amount of memory or confirming the computer is plugged in could be useful in other scenarios. This type of information would not enable you to determine the problem in this scenario.
A user reports that she cannot print from her computer. You also notice that they are unable to reach a supplier’s web site. The operating system is Windows 8.1. Which command should you start with to help with your diagnosis?
A) route
B) nmap
C) dig
D) ping
The ping command allows you to test the connection between a local computer and a node on the network. If you are trying to determine why a user cannot print, you can issue the ping command with either the printer’s network name (ping colorprinter) or the IP address of the printer (ping 192.168.1.38). If you could ping by IP address, but not by network name, that would indicate a problem with DNS translation.
What are the nmap Linux function?
The nmap Linux command is used to explore the network. It also acts as a security scanner. As an example, you can use nmap 192.168.1.0/24 to scan a subnet.
What are the functions of the route add command?
The route command can be used to add additional routes (path) in your network. As an example, if you decided that traffic from some computers needed to go to another node in the network, you would use a route add command.
You work for a company that deploys wireless networks for your customers. You have been asked to deploy wireless range extenders for several companies. For which of the following situations does deploying a wireless range extender make sense?
A) For a new branch office opening 7 km away from the main office, where 5-10 users will need wireless network access at the same time
B) To add wireless coverage for an office expansion to 10th floor, where up to 40 users might need wireless access at the same time
C) For the back porch of a coffee shop where as many as 30 users might need wireless network access at the same time
D) For a deli dining area in a grocery store, where up to 35 patrons may need wireless access at the same time
E) For a sprawling small office/home office layout with no more than 10 devices active at any given time, but with two dead spots in need of improved wireless network access
The only situation in which deploying a wireless range extender would make sense is for a sprawling small office/home office layout (SOHO) with no more than 10 devices active at any given time, but with two dead spots in need of improved wireless network access. A wireless range extender provides wireless coverage for a larger area than a single wireless access point can handle on its own. Strategically placed range extenders can also deliver wireless coverage in areas where low-signal or no-signal conditions may prevail when only a single WAP is used. In fact, wireless extenders will provide something less than the square of the area that a single WAP covers, because they must stay close enough to the WAP to receive a strong enough signal for them to meaningfully extend that signal further afield.
As the name indicates, a wireless range extender simply extends an existing wireless network, usually provided by a wireless access point that also includes multiple switched ports and built-in router capabilities (along with USB ports, DHCP, address and content filtering, and more). Low cost range extenders offer none of these additional functions; more expensive models may include some of these. In general, a range extender should not be expected to handle more than 20 or 25 simultaneously connected devices, whereas wireless access points can typically handle up to 60 devices each. Thus, wireless range extenders apply only to small-scale, low-usage scenarios like the small office/home office situation described.
The network you administer is a Fast Ethernet network. Wall outlets are connected to patch panels by 90-meter cables. Patch panels are connected to switches by 5-meter cables. The network uses Category 5 unshielded twisted-pair (Cat5 UTP) cable.
You use a 15-meter patch cable to connect a server named Shipping to a wall outlet. You connect the Shipping computer to the network, start the computer, and properly configure it. However, clients cannot connect to the Shipping server. Clients can connect to other servers on the network. What will most likely solve the connection problem?
A) replacing the 15-meter patch cable with a 3-meter patch cable
B) replacing the Cat5 UTP with Cat3 UTP
C) replacing the 15-meter patch cable with a 10-meter patch cable
D) replacing the Cat5 UTP with Cat1 UTP
On a Fast Ethernet network that uses unshielded twisted-pair (UTP) cables, such as a 100Base-TX Ethernet network, the maximum length of the cable between a computer and a switch or hub is 100 meters. In this scenario, the total length of cable between the Shipping server and the switch is 110 meters. You can solve the connection problem in this scenario by replacing the 15-meter patch cable that connects the Shipping server to the wall outlet with a patch cable that is no more than 5 meters in length. Db loss in cabling (also called attenuation) occurs because the voltage decays slowly as the current travels the length of the cable. If you replace the 15-meter patch cable with a 10-meter patch cable, then the connectivity problem will still occur because the overall cable length between the server and the switch will still exceed 100 meters.
The switch and patch panel are usually located within a telecommunications closet. A basic patch panel does not normally contribute any networking services; it simply serves as a junction box between the switch and the various nodes on the network. A patch panel provides a convenient interface from which you can arrange and rearrange connections between the switch and the nodes.
Distance issues are caused when cable lengths exceed the maximum distance allowed by a particular media type. Ensure that your cable runs do not exceed the maximum distance allowed. Repeaters could also be used to prevent this problem.
Physical connectivity problems include?
Bad connectors
Bad wiring
Open circuits or short circuits
Split cables
Transmit (TX)/Receive (RX) ends reversed
Cable placement
EMI/Interference
Cross-talk
Db loss and attenuation
Distance limitations
Incorrect termination (mismatched standards)
Split pairs
Bad SFP/GBIC (cable or transceiver)
Prior to deploying a new wireless access point at a retail store that is located in a strip mall, you decide to perform a site survey. Which statements describe the purpose of doing this? (Choose 2)
A) to calculate the hop count to the gateway
B) to find the frequency and power settings to be used on access points
C) to find out the server processing speed required
D) to calculate the number of access points required for the coverage area
E) to find out the required Internet bandwidth
Site surveys are done to assess the coverage area of each access point and the number of access points required for a specified coverage area.
A site survey should be done prior to installing a WLAN. Site surveying is required to determine the frequency and power settings of each access point to avoid channel overlapping and interference. A site survey is the only technique that helps the customer install complete WLAN coverage for mobile roaming clients. After a proper site survey, a site survey engineer can identify the position of access points within the facility. The quality of the output of the site survey depends on the experience and knowledge of the site survey engineer.
End-to-end connectivity is a process whereby you troubleshoot connectivity issues from the host experiencing the connection problem all the way through the network. You should always start at the local host and proceed through the network, through routers and other devices, to the destination. Any connectivity problem could be at the host, the remote host, or anywhere in between. Following a logical process will ensure that the exact issue will be located.
Connectivity issues: “Incorrect interface/interface misconfiguration”
Incorrect interface/interface misconfiguration − If the interface is incorrectly configured, then traffic will not pass through that interface properly. Often the easiest way to test and interface is to use the ping command or a loopback tester. If you connect a router to a multiplexer but cannot access the router’s interface even though the signal level is good, it is most likely that the wrong wavelength as demuxed from the multiplexer.
Connectivity issues: “Interface Errors”
Interface errors − Interface errors are usually dependent upon the device and vendor. You should consult the device’s operation manual to determine what the interface error means. In most cases, vendors have an online knowledge base that you can search.
Connectivity issues: “Simultaneous wired/wireless connections”
Simultaneous wired/wireless connections − Some organizations have both wired and wireless networks in use. Client computers, though, should connect to only one of these types of networks. If you want to use a wired connection, you should plug into that network. If a wireless network is in range, your computer may attempt to connect to the wireless network as well if you have enabled the connect automatically feature.
Connectivity issues: “Discovering neighboring devices/nodes”
Discovering neighboring devices/nodes − Most devices have the ability to discover neighboring devices or nodes by using the appropriate routing protocol. It may be necessary to enable multiple routing protocols based on the types of devices to which you must connect.
Connectivity issues: “Port configuration”
Port configuration − Each switch port is a single collision domain. If you improperly configure the ports, then communication on the appropriate domain may not be possible.
Connectivity issues: “VLAN assignment”
VLAN assignment − This problem occurs when configuring the VLAN assignment on a client computer or device. Each VLAN is a separate collision domain. Make sure that client computers are configured with the appropriate VLAN to ensure that they can communicate within the collision domain. If a device is attached to an incorrect VLAN, it will not respond to network communication even through the link activity light is on.
You need to deploy wireless access points in a college environment. You want to deploy a solution that will provide the shortest range and the most non-overlapping channels to prevent interference. Which wireless standard should you deploy?
A) 802.11a
B) 802.11x
C) 802.11b
D) 802.11g
You should deploy the 802.11a wireless standard. This standard provides the most non-overlapping channels (eight) and the shortest range (30 m in an open environment, 10 m in a building). The 30 meter (m) distance limitation is an important consideration when implementing this wireless network. This standard is the best to use in a campus environment where multiple wireless access points may be deployed near each other.
The 802.11b and 802.11g wireless standards provide only three non-overlapping channels. In addition, they provide a range of up to 100 m in an open environment and 30 m in a building.
A user in the Engineering department is unable to log on to the network. The network has eight subnets and uses TCP/IP. There have been no other complaints from other departments. Which steps should help you isolate the cause of the problem? (Choose 2)
A) Ping the server.
B) Establish whether other local-segment users are having the same problem.
C) Configure a WINS server.
D) Replace all the patch cables.
When troubleshooting a problem, you should try the obvious or quick fixes first. This is especially true when you are attempting to correct a problem remotely with a non-technical and often impatient end user.
A logical first place to start troubleshooting would be to determine if the condition is network-wide or workstation-specific. You should have other similar users attempt to perform the same actions. If they are able to do so, the problem is a local condition. Next, you should ping the server from the user’s computer.
You just installed a replacement switch that was moved from one part of the network to a new location. After all the patch cables are reconnected, some users cannot communicate via e-mail. What is the most likely issue?
A) Bad port
B) Attenuation
C) VLAN mismatch
D) Network connection LED status indicators
VLAN mismatch occurs when the VLAN assigned to the port on one end of the cable does not match the VLAN assigned to the port on the other end of the cable. In a native VLAN mismatch, one port might be assigned to VLAN 10, and the other assigned to VLAN 100. This can cause a security risk, as the traffic may not go where intended. In a trunk VLAN mismatch, one port is configured to trunk mode off, and the other is configured to trunk mode on. In this last case, the trunk link would no longer be functional. This would explain why some but not all of the users are unable to communicate via e-mail.
what do you do when you experience bad port on a switch, hub or router?
A bad port on a switch, hub, or router will cause connectivity issues for all users, not select users, when communicating with that port. When connected, a port should have a connectivity light, and when transmitting data, should have a data light. If a bad port is suspected, plug the patch cable into another empty port. If you get traffic, the original port was bad. To shut down suspected bad port 11, enter the following commands:
Switch(config)# interface Fa0/11
Switch(config-if)# shutdown
Indicators of a Network Connection via LED status?
Network connection LED status indicators on ports and NICs tell you whether you have a network connection and whether there is traffic on that connection. For switch ports, the LED indicators are usually on the left and right sides of the port. The left LED usually indicates a network connection. In some equipment, an amber light would indicate a 100mbs connection, while a green light would indicate a 1000mbs connection. The right LED will blink to notify that there is network activity on that port.
ElliotA, KateB, and PayR are workstations. FileSrv is a file server, and WebSrv is a Web server. FRW1 and FRW2 are firewalls. WebSrv is on a demilitarized zone (DMZ) that is maintained between the two firewalls. Router1 connects the network to the Internet. Remote users on the Internet connect to WebSrv, and some remote users on the Internet are allowed to gain access to files on FileSrv.
Users report a network connectivity problem, so you test network connectivity. ElliotA can connect to KateB and FileSrv. KateB can connect to WebSrv. WebSrv can connect to PayR and FileSrv. FileSrv cannot connect to Router1, but FileSrv can connect to FRW1 and FRW2. Internet users can connect to Router1, but they cannot connect to WebSrv.
What is most likely causing the connectivity problem on the network?
A)FRW1 is configured with an invalid IP address.
B)Router1’s connection to the Internet is down.
C)The cable that connects Router1 to FRW2 is not properly connected to FRW2.
D)Router1 is overloaded with network traffic.
E)The port on Hub1 that connects FileSrv to the hub is not able to send or receive data.
The most likely cause of the network connectivity problem in this scenario is that the cable that connects Router1 to FRW2 is not properly connected to FRW2. If the cable is not properly connected, then users on the Internet will be able to contact Router1, but they will not be able to gain access to resources on WebSrv. Also, computers on the network will be able contact one another and the firewalls, but they will not be able to contact Router1 or connect to the Internet. Potential issues with the cable are a bad connector, bad internal wiring, a split (a physical cut in the cable), or a termination problem.
Potential issues with cables: Bad Connectors?
Bad connector − If you suspect that a connector is bad on a short cable, it may be easier to replace the entire cable than one connector. However, for long cable runs that extend over a long distance, you should replace the connector so that the cable will not have to be re-routed.
Potential issues with cables: Bad Wiring?
Bad wiring − If you suspect that the cable itself is damaged or nonfunctional, you should always replace the cable.
Potential issues with cables: Split Cables?
Split cables − This is similar to bad wiring but is much easier to diagnose because the cable is actually cut. An open circuit can be the direct result of this issue.
Potential issues with cables: Incorrect termination?
Incorrect termination − This occurs when the cabling connectors are configured with the wrong individual pin in the connector sockets, or when a twisted pair cable is wired as a split pair.
Potential issues with cables: Straight-through?
Straight-through − With this type of cable, each pin should connect to the same pin on the opposite side. This cabling is used when connecting unlike devices, such as connecting a router to a hub, a computer to a switch, or a LAN port to a switch, hub, or computer.
Crossover Cable?
Crossover − With this type of cable, some of the internal wires should cross over each other by switching the orange-white and green-white wires, and then the orange and green wires. This cabling is used when connecting like devices, such as connecting a computer to a router, a computer to a computer, or a router to a router.
Potential issues with cables: Dirty optical cables?
Dirty optical cables – Cleanliness is important with fiber optic cables and directly impacts the performance of optical communication networks. A dirty optic cable on either connecter end can create severe problems.
Potential issues with cables: TX/RX reversal?
TX/RX reversal is another kind of cabling error. A straight-through cable has the same transmit (Tx) or receive (Rx) leads at each end, while they are reversed at one end in a crossover cable. A straight-through cable connects dissimilar devices, while a crossover cable connects like devices. If you use a crossover cable in the wrong location on the network, the device will be unable to connect to the network. You should replace the cable with the correct type.
Some switches support medium dependent interface crossover (MDIX). This allows a switch port to match its leads to the cable you have used. However, if a network device does not support MDIX, you must use an appropriate cable (that is, a crossover cable) to allow its Tx leads to connect to the Rx leads on a connected device. If loss of connection occurs, you are using the wrong cable or have the switch leads configured incorrectly.
How does a split pair occur in wiring error?
A split pair is a wiring error where two wires of a twisted pair are instead connected using two wires from different pairs. It most commonly occurs when a punch-down block is wired incorrectly or when RJ-45 connectors are crimped onto the wrong wires. In both of these situations, you will need to rewrite the block or connector. Open circuits or short circuits could also cause loss of connection.
An open circuit is usually the result of a broken cable or improper termination. This causes an incomplete connection and complete failure of the electric current.
A short circuit occurs when there is unwanted contact with the cabling. This results in the current following an unwanted path, which could cause overheating or burning.
You need to check an IP connection end-to-end at the Network layer. Which tool should you use?
A) telnet
B) trace
C) ping
D) show
The ping command checks the connection to the router end-to-end at the Network layer. It uses the ICMP protocol to send Echo requests and replies to check connectivity to another network host. To ping the address 110.11.32.3, you should enter the following command:
ping 110.11.32.3
You are issued a network technician toolkit that contains several tools. Match the tools on the left to the descriptions on the right. Move the correct items from the left column to the column on the right to match the tools with the descriptions.
Toner Probe − Verifies that a cable is good
Loopback plug − Attaches media connectors to the ends of the cable
Crimper − Echoes signals over a port to ensure it is working properly
Punchdown tool − Includes a voltmeter, an ohmmeter, and an ammeter to measure voltage, current, and resistance, respectively
Multimeter − Attaches cable to a patch panel
Cable tester − Includes a tone generator and a tone locater to locate the ends of a cable
Cable tester − Verifies that a cable is good
Crimper − Attaches media connectors to the ends of the cable
Loopback plug − Echoes signals over a port to ensure it is working properly
Multimeter − Includes a voltmeter, an ohmmeter, and an ammeter to measure voltage, current, and resistance, respectively
Punchdown tool − Attaches cable to a patch panel
Toner probe − Includes a tone generator and a tone locater to locate the ends of a cable
You are troubleshooting a connectivity problem with a computer named Computer1 on a network that has a router with the IP address 192.168.10.1. The network uses a non-subnetted Class C IP address range. Computer1 is configured with an IP address of 192.168.10.255 and a default gateway address of 192.168.10.1. The computers on the network are configured with the subnet mask 255.255.255.0. Computer1 cannot connect to the other nodes on the network. The link lights on Computer1’s network interface card (NIC) are lit.
What is most likely causing the connectivity problem?
A) the subnet mask used on the network
B) Computer1’s IP address
C) Computer1’s default gateway address
D) the router’s IP address
E) Computer1’s NIC
Of the choices listed, Computer1’s IP address is most likely causing its connectivity problem. Computer1 is configured with the broadcast address for the network, and thus cannot communicate on the network. The network address 192.168.10.1 with a subnet mask of 255.255.255.0 can also be represented as 192.168.10.1/24. The slash (/) character and the number that follows it represent the network prefix, which indicates the number of bits in an IP address that are used for the network address. In this scenario, the first three octets are used as the network address and the last octet is used for host addresses because it is a class C address range. Therefore, the router’s network address is 192.168.10 and its host address is 1. IP addresses from 192.168.10.1 through 192.168.10.254 are valid host addresses on the network. In this scenario, the address 192.168.10.0 is the network ID for the network.
A user is complaining about wireless connectivity. Their cubicle is on a concrete wall, and the wireless access point is mounted on the other side of the wall. What describes what is happening to the wireless signal that only has to travel a few inches?
A) Absorption
B) Attenuation
C) Frequency mismatch
D) Refraction
Absorption occurs when an object does not reflect or refract a wireless signal, but rather absorbs a portion of it. Different materials have different absorption rates. For example, drywall has a relatively low absorption rate, while concrete has a relatively high absorption rate.
Your company is located in Charlotte, North Carolina. Management has decided to deploy multiple 802.11a WLANs. You are concerned that there are not enough non-overlapping channels to support the number of access points that you need to deploy. How many non-overlapping channels are supported in this deployment?
A)four
B)eleven
C)three
D)twenty-three
The 802.11a wireless local area network (WLAN) technology supports twenty-three non-overlapping or non-interfering channels that can be used in a single area.
Wireless access points or bridges must use non-adjacent, non-overlapping radio channels to prevent interference from the adjacent ones. Each 802.11a channel utilizes a RF bandwidth of 20 MHz in Orthogonal Frequency Division Multiplexing (OFDM) modulation. This 20-MHz channel is split into 52 channels with 300-KHz smaller sub-carriers, out of which 48 are used for data transmission. The eight non-overlapping channels can be used in a single area or cell to provide the cell a total bandwidth up to 532 Mbps.
802.11b includes four non-overlapping channels (channels 1, 6, 11, 14) in most countries, and 802.11g includes four non-overlapping channels (channels 1, 5, 9, and 13) in most countries. In the US, 802.11b includes the same four non-overlapping channels, but 802.11g includes three non-overlapping channels (channels 1, 6, and 11).
Your company has recently replaced all the shielded twisted pair (STP) and unshielded twisted pair (UTP) cable with fiber optic cable. You need to purchase a device to determine the length of the cables used on your network. Which tool do you need?
A) butt set
B) OTDR
C) toner probe
D) TDR
An optical time domain reflectometer (OTDR) can be used to determine the length of the cables used on a fiber optic network. A time domain reflectometer (TDR) determines the length of shielded twisted-pair (STP), unshielded twisted-pair (UTP), or coaxial cables.
A butt set is used to test telephone lines. A toner probe is used to identify a single cable on the network. It is the best tool to use to locate a bad Cat5 cable.
A contractor is unable to connect to your wireless network using his 802.11g wireless adapter. What is the most likely problem?
A)You are using an incorrect channel on your network.
B)You have an 802.11n network.
C)You have an 802.11b network.
D)You have an 802.11a network.
It is most likely that you have an 802.11a network because 802.11g devices are incompatible with 802.11a networks. The frequency used by the different wireless networks is important. Some of them use the same frequency and can, therefore, be considered compatible. However, keep in mind any other devices, such as cordless phones, that can use the same radio frequency as they can cause interference.802.11g devices are compatible with 802.11b networks.802.11n networks allow the usage of 802.11a, 802.11b, or 802.11g devices.
What are the consideration when it comes wireless standards? Name Four?
Throughput − Each wireless network type has a different maximum throughput. Keep in mind that this throughput is shared by all the devices connected to the wireless access point.
Frequency − Each wireless network uses a certain frequency. Some network types may use the same frequency. Document the frequencies used when you implement any wireless network so that you can ensure that future wireless networks do not interfere with existing ones.
Distance − All wireless access points will have a limited distance for their signal. You can increase and decrease the signal strength as needed, but the maximum distance will always remain. In most cases, companies decrease the signal strength to limit the area covered by the wireless network.
Channels − Each wireless network can operate over several channels that can be used by that frequency. Research the frequency in use to determine the non-overlapping channels. While there may be 10 channels available, usually only three or four of the available channels are considered non-overlapping. Wireless access points that use the same frequency should be configured to use different non-overlapping channels.
Channel Utilization − This refers to the fraction of time that is needed to transmit data packets over a given channel. This process is handled by a scheduling mechanisms that will check to make sure that the data packets are capable of being sent over a particular channel and that it will not impact network speeds and waste resources.
A user has just returned from a week-long conference. While attending the conference, the user connected their work laptop to both the hotel Wi-Fi and the conference Wi-Fi. Now the user cannot connect to the company’s Wi-Fi. What is most likely the issue?
A) Jitter
B) Latency
C) Frequency mismatch
D) Wrong SSID
The most likely issue is an incorrect Service Set Identifier (SSID). Most wireless devices remember the previous SSID, even if you move to a new network, so you should always check the SSID when troubleshooting. Also, it is very easy for a user to select the wrong SSID. They may not have the correct password or passphrase, and they may type in the SSID name incorrectly. Checking for the correct SSID is often the first step to wireless troubleshooting. On most devices, you can set the device to remember an SSID and its credentials. However, if the SSID or the credentials change, the device will be unable to automatically log in to the wireless network.
You are troubleshooting a connectivity problem on an Ethernet network that contains both NetWare and Windows servers. A Windows 7 client cannot connect to the Internet or any network resources. However, other computers on the same subnet as the client can access network resources and the Internet. You issue the ipconfig command at the workstation and find that the IP address is 169.254.184.25 and the subnet mask is 255.255.0.0. This IP network and subnet are different from the IP network and subnet that other computers on the same segment are using. What is the most likely problem?
A) The client obtained the IP address from a DHCP server it found on the Internet.
B) The client obtained the IP address from a NetWare server.
C) The client obtained the IP address from a Windows server.
D) The client selected the IP address using APIPA.
Automatic Private IP Addressing (APIPA) is a feature of Windows operating systems that enables a system to automatically assign itself an IP address when a DHCP server is not available. APIPA acts as a DHCP failover mechanism, making support easier for small local area networks. If APIPA addresses are in use, you should discover why the DHCP server cannot be contacted. The problem could be with the connection to the DHCP server or with the DHCP server itself.
APIPA uses the Address Resolution Protocol (ARP) to select a unique IP address in the reserved address range of 169.254.0.0 to 169.254.255.255 and a subnet mask of 255.255.0.0 when no DHCP server is available. Once the system has assigned itself an IP address, it can communicate with other devices on the LAN using TCP/IP, provided the devices are either configured for APIPA or manually set to the correct address range and a subnet mask.
