5.4 Troubleshoot common performance issues Flashcards
Employees in a certain office area are complaining that it is difficult to browse the web while on the wireless network. The network engineer reconfigures the access point to a lesser-used frequency to limit the surrounding businesses’ wireless issues.
What is the MOST likely issue that the network engineer resolved?
An employee submits a ticket stating that the wireless signal is only 10 strength at their desk, making it hard for the employee to browse the shared drive and internet.
What would a network engineer completing a site survey be able to determine is the cause?
A system administrator is researching a connectivity issue. The administrator notes that the physical link listed as up, but the line protocol is listed as down.
What should the system administrator investigate to resolve the issue?
- Bandwitdth
- Encapsulation Errors
- Jitter
- Link States
Encapsulation Errors
Encapsulation is the frame format expected on the interface. Encapsulation errors will prevent transmission and reception. If the system administrator checks the interface status, the physical link will list it as up, but the line protocol will list it as down.
Defined as being a variation in the delay, jitter manifests itself as an inconsistent rate of packet delivery.
Bandwidth is the total capacity to process network traffic. Improving bandwidth would improve connecting to the internet.
Link state measures whether an interface is working (up) or not (down). The system administrator would configure the link state of a given port on a switch or router to turn it on or off.
Data travels across the network for a period of time and encounters many types of interference and errors on the first two network layers.
What is the data received at the destination and measured at the network or transport layers known as?
- Power over ethernet
- Speed
- Attenation
- Throughput
Throughput
Throughput is an average data transfer rate achieved over a period of time, excluding errors incurred at the physical and data link layers and measured at the network or transport layer.
The performance of a link that the cabling team has properly installed to operate at 10 Mbps, 100 Mbps, 1 Gbps, or better, is known as the speed.
Attenuation is the loss of signal strength, often caused by too much distance. It is the ratio between the signal strength at origin and signal strength at destination expressed in decibels.
Power over Ethernet (PoE) supplies electrical power from a switch port over standard data cabling to a connected powered device (PD).
A system administrator is investigating an issue with two geographically distant offices. Users at these locations report that accessing the shared drive at the corporate office is taking too long, even though all three locations have gigabit-speed internet.
What indicator should the system administrator investigate first to help resolve the issue?
- Memory
- Latency
- Jitter
- Processor
Latency
Latency refers to the time it takes for a packet to leave a computer, traverse the network, complete its request and return to the original device, measured as Round Trip Time.
Memory refers to the component of computers that temporarily stores actively used data. Improving memory would allow larger, more intensive programs to run better.
The Central Processing Unit (CPU) refers to the component in a device that executes commands given to it by a program or operating system.
Defined as being a variation in the delay, jitter manifests itself as an inconsistent rate of packet delivery.
An employee submits a ticket stating that the wireless signal is only 10 strength at their desk, making it hard for the employee to browse the shared drive and internet.
What would a network engineer completing a site survey be able to determine is the cause?
- Distance
- Frequency mismatch
- Interference
- Incorrect Passphrase
Distance
Wireless access points can only broadcast radio signals a certain distance. The further away from the wireless access point, the less signal strength, leading to poor connections.
To connect to an AP (Access Point), a station must match the standards compatibility and frequency selection configured on the AP.
A wireless network can use a pre-shared key which means using a passphrase. A user connecting to a wireless network will need to know the correct passphrase for authentication.
Interference can be caused by several factors, including neighboring equipment that may use the same frequency of radio waves.
Employees report that when they move to certain areas of the office, their internet connection drops. The network engineer decides to complete a site survey and identifies what the issue might be.
What is the MOST likely issue causing the internet connection drops for employees?
- Speed
- Interference
- Frequency Mismatch
- Insufficient Wireless Coverage
Insufficient Wireless Coverage
A wireless laptop at an organization is not able to access any internal network resources, but can browse the Internet. An IT support specialist finds the cause of the problem after examining the laptop.
Based on the symptoms, what does the specialist most likely conclude the issue to be?
- Security type mismatch
- Incorrect antenna type
- Wrong service set identifier
- Wrong passphrase
Wrong Service Set Identifier
A Service Set Identifier (SSID) identifies a network. Connecting to an incorrect network is common when a location has multiple networks with varying access to resources (such as found with a guest network versus a private network).
A user connecting to a wireless network will need to know the correct passphrase for authentication and to obtain a connection.
An incorrect antenna type may adversely affect the signal strength at any given point. A unidirectional (not omnidirectional) antenna is suitable for direct point-to-point connections.
A variety of security types can be used in a wireless network. A mismatch will cause a connection to fail. In this case the connection does not fail but internal resources cannot be accessed.
A system administrator is researching a connectivity issue. The administrator sees the physical link listed as up, but the line protocol listed as down.
What is the MOST likely issue that the system administrator should investigate?
- Encapsulation Errors
- Bandwidth
- Link states
- Jitter
Encapsulation Errors
Encapsulation is the frame format expected on the interface. Encapsulation errors will prevent transmission and reception. If the system administrator checks the interface status, the physical link will list it as up, but the line protocol will list it as down.
Defined as being a variation in the delay, jitter manifests itself as an inconsistent rate of packet delivery.
Bandwidth is the total capacity to process network traffic. Improving bandwidth would improve connecting to the internet.
Link state measures whether an interface is working (up) or not (down). The system administrator would configure the link state of a given port on a switch or router to turn it on or off.
What is the most likely cause of a network experiencing continual bottlenecks?
- Seasonal increases in web traffic
- Occasional video conferncing
- Scheduled Nightly Backups
- Device Related Issues
Device Related Issues
Continual bottlenecks in a network are most likely due to device-related issues. This can include hardware that is underpowered, outdated, or malfunctioning, which cannot handle the regular data flow efficiently. Such devices become persistent choke points, reducing the overall network performance regardless of the specific type or volume of traffic.
Seasonal increases in web traffic can lead to temporary bottlenecks during specific periods but are not the cause of continual bottlenecks. Once the seasonal increase subsides, the bottleneck should resolve if the network devices are adequate.
Scheduled nightly backups can cause increased network load and potential bottlenecks during the backup window, but these are not continual. The network should return to normal performance after the backups are completed.
Occasional video conferencing can strain network resources, leading to temporary bottlenecks, especially if multiple high-definition streams are involved. However, these bottlenecks are event-specific and not continual, resolving once the conferencing activity ends.
An IT engineer notices that wireless network performance is at an all-time low. After reviewing the wireless console settings, the engineer makes changes to eliminate device saturation.
Which problem did the engineer address?
- Overcapacity
- Interference
- Jitter
- Channel Overlap
Overcapacity
Overcapacity (or device saturation) occurs when too many client devices connect to the same AP (Access Point). The maximum number of clients that an AP can support varies, depending on the Wi-Fi standard used and the type of network traffic generated.
Interference can be caused by a number of factors including neighboring equipment that may use the same frequency of radio waves.
Jitter is similar to latency, however, rather than steady delays, jitter is a variable delay in the Round Trip Time (RTT) of packets.
A multi-access point site should be able to allow clients to operate with the strongest signal and function with a minimum of Co-Channel Interference (CCI). At least 25 MHz spacing should be allowed to avoid channel overlap.
Employees are complaining that when browsing the company’s web-based Content Relationship Management system, the access is slow and often fails.
The company has 500 employees that use this system, and the contracted internet speed is 10Mbps download and 1Mbps upload.
What should the system administrator increase in order to improve access to the cloud system?
- Memory
- Bandwidth
- Speed / Duplex Settings
- Packet Count
Bandwidth
Bandwidth is the total capacity to process network traffic. Improving bandwidth would improve connecting to the internet.
It is often useful to monitor packet counts. High packet counts will incur processing load on the CPU and system memory resources of the appliance, even if the size of each packet is quite small.
Half duplex refers to only being able to transfer or receive one at a time. Full duplex refers to being able to transfer and receive at the same time.
Memory refers to the component of computers that temporarily stores actively used data. Improving memory would allow larger, more intensive programs to run better.
A network engineer is investigating an issue with the wireless network. The office building they are in has quite a few different businesses nearby. To resolve the issue the network engineer switched one of the settings to resolve any conflicts with the other businesses’ wireless networks.
What BEST describes the cause of the issue?
- Speed
- SSID
- Chanel Overlap
- Security Type
Channel Overlap
Channel overlap refers to interference issues resulting from multiple access points that are all in range of one another and are configured to use similar wavelengths.
Speed refers to how fast a piece of network equipment can transfer data. Older access points may have a slower speed, such as a theoretical upload speed of 150Mbps, while newer ones maybe two or three times that.
Today’s wireless devices are equipped to use the latest security type and rarely ask the user to specify a security type.
A Service Set Identifier (SSID) identifies a network, and the value is case-sensitive. A user will need to know the proper SSID to connect to.
What causes congestion on a network?
- A decrease in network usage
- The use of QoS mechanisms
- An increase in network security protocols
- The network’s inability to meet peak load demands
The network’s inability to meet peak load demands
Congestion occurs when the network infrastructure cannot handle the demands of peak load, leading to queued or dropped packets. This is a capacity issue where the infrastructure’s limitations prevent it from accommodating all requests efficiently.
A decrease in network usage would actually alleviate congestion, not cause it.
An increase in network security protocols might affect network performance but is not a direct cause of congestion.
The use of Quality of Service (QoS) mechanisms is intended to manage bandwidth and prioritize traffic to mitigate congestion, not cause it.
Users are reporting that their phone calls are garbled and are often of poor quality.
What should the system administrator investigate first to resolve the issue?
- Logging levels
- Jitter
- Severity Levels
- Speed Duplex Settings
Jitter
Defined as being a variation in the delay, jitter manifests itself as an inconsistent rate of packet delivery. Jitter is apparent in phone or voice over internet protocol calls, manifesting as garbled audio.
Logging levels refer to the threshold for storing or forwarding an event message based on its severity index or value.
Severity levels is another phrase for logging levels and refers to the categorization and logging of events based on a predetermined value.
Half duplex refers to only being able to transfer or receive one at a time. Full duplex refers to being able to transfer and receive at the same time. Having multiple devices configured differently can cause collisions.
