Module 9-12: Optimize, Monitor, Troubleshoot Networks Flashcards
What is the benefit of deploying Layer 3 QoS marking across an enterprise network?
Layer 3 marking can carry QoS information on switches that are not IP aware.
Layer 3 marking can be used to carry non-IP traffic.
Layer 3 marking can be carried in the 802.1Q fields.
Layer 3 marking can carry the QoS information end-to-end.
Layer 3 marking can carry the QoS information end-to-end.
Answers Explanation & Hints:
Marking traffic at Layer 2 or Layer 3 is very important and will affect how traffic is treated in a network using QoS.
Layer 2 marking of frames can be performed for non-IP traffic.
Layer 2 marking of frames is the only QoS option available for switches that are not “IP aware.”
Layer 3 marking will carry the QoS information end-to-end.
What is the function of a QoS trust boundary?
A trust boundary identifies the location where traffic cannot be remarked.
A trust boundary identifies which devices trust the marking on packets that enter a network.
A trust boundary only allows traffic to enter if it has previously been marked.
A trust boundary only allows traffic from trusted endpoints to enter the network.
A trust boundary identifies which devices trust the marking on packets that enter a network.
Answers Explanation & Hints:
Network traffic is classified and marked as close to the source device as possible. The trust boundary is the location where the QoS markings on a packet are trusted as they enter an enterprise network.
What are two approaches to prevent packet loss due to congestion on an interface? (Choose two.)
Prevent bursts of traffic. Drop lower-priority packets. Decrease buffer space. Disable queuing mechanisms. Increase link capacity.
Increase link capacity.
Drop lower-priority packets.
Answers Explanation & Hints:
There are three approaches to prevent sensitive traffic from being dropped:Increase link capacity to ease or prevent congestion.
Guarantee enough bandwidth and increase buffer space to accommodate bursts of traffic from fragile flows.
Prevent congestion by dropping lower-priority packets before congestion occurs.
What configuration scenario would offer the most protection to SNMP get and set messages?
SNMP community strings
SNMPv2 for in-band management with read-write community strings
SNMPv3 configured with the auth security level
SNMPv1 with out-of-band management in a private subnet
SNMPv3 configured with the auth security level
Answers Explanation & Hints:
SNMPv3 supports authentication and encryption with the auth and priv security levels. SNMPv1 and SNMPv2 do not support authentication or encryption. Using a default community string is not secure because the default string of “public” is well known and would allow anyone with SNMP systems to read device MIBs.
Refer to the exhibit. The network administrator enters these commands into the R1 router:
R1# copy running-config tftp
Address or name of remote host [ ]?
When the router prompts for an address or remote host name, what IP address should the administrator enter at the prompt?
https://infraexam.com/wp-content/uploads/2020/11/CCNA3-v7-%E2%80%93-ENSA-%E2%80%93-Modules-9-%E2%80%93-12-Optimize-Monitor-and-Troubleshoot-Networks-Exam-Answers-09.jpg
- 168.9.254
- 168.10.1
- 168.10.2
- 168.11.252
- 168.11.254
192.168.11.252
Answers Explanation & Hints:
The requested address is the address of the TFTP server. A TFTP server is an application that can run on a multitude of network devices including a router, server, or even a networked PC.
The command ntp server 10.1.1.1 is issued on a router. What impact does this command have?
determines which server to send system log files to
identifies the server on which to store backup configurations
ensures that all logging will have a time stamp associated with it
synchronizes the system clock with the time source with IP address 10.1.1.1
synchronizes the system clock with the time source with IP address 10.1.1.1
As the network administrator you have been asked to implement EtherChannel on the corporate network. What does this configuration consist of?
providing redundant links that dynamically block or forward traffic
grouping multiple physical ports to increase bandwidth between two switches
grouping two devices to share a virtual IP address
providing redundant devices to allow traffic to flow in the event of device failure
grouping multiple physical ports to increase bandwidth between two switches
Answers Explanation & Hints:
EtherChannel is utilized on a network to increase speed capabilities by grouping multiple physical ports into one or more logical EtherChannel links between two switches. STP is used to provide redundant links that dynamically block or forward traffic between switches. FHRPs are used to group physical devices to provide traffic flow in the event of failure.
What is a definition of a two-tier LAN network design?
access and core layers collapsed into one tier, and the distribution layer on a separate tier
access and distribution layers collapsed into one tier, and the core layer on a separate tier
distribution and core layers collapsed into one tier, and the access layer on a separate tier
access, distribution, and core layers collapsed into one tier, with a separate backbone layer
distribution and core layers collapsed into one tier, and the access layer on a separate tier
Answers Explanation & Hints:
Maintaining three separate network tiers is not always required or cost-efficient. All network designs require an access layer, but a two-tier design can collapse the distribution and core layers into one layer to serve the needs of a small location with few users.
Match the functions to the corresponding layers. (Not all options are used.)
https://infraexam.com/wp-content/uploads/2020/11/CCNA3-v7-%E2%80%93-ENSA-%E2%80%93-Modules-9-%E2%80%93-12-Optimize-Monitor-and-Troubleshoot-Networks-Exam-Answers-001.png
What are two reasons to create a network baseline? (Choose two.)
to determine what kind of equipment to implement
to evaluate security vulnerabilities in the network
to identify future abnormal network behavior
to design a network according to a proper model
to determine if the network can deliver the required policies
to select a routing protocol
to identify future abnormal network behavior
to determine if the network can deliver the required policies
Answers Explanation & Hints:
A network baseline is created to provide a comparison point, at the time that the network is performing optimally, to whatever changes are implemented in the infrastructure. A baseline helps to keep track of the performance, to track the traffic patterns, and to monitor network behavior.
A computer can access devices on the same network but cannot access devices on other networks. What is the probable cause of this problem?
The cable is not connected properly to the NIC.
The computer has an invalid IP address.
The computer has an incorrect subnet mask.
The computer has an invalid default gateway address.
The computer has an invalid default gateway address
Answers Explanation & Hints:
The default gateway is the address of the device a host uses to access the Internet or another network. If the default gateway is missing or incorrect, that host will not be able to communicate outside the local network. Because the host can access other hosts on the local network, the network cable and the other parts of the IP configuration are working.
In which step of gathering symptoms does the network engineer determine if the problem is at the core, distribution, or access layer of the network?
Document the symptoms. Determine the symptoms. Gather information. Determine ownership. Narrow the scope.
Narrow the scope.
Answers Explanation & Hints:
In the “narrow the scope” step of gathering symptoms, a network engineer will determine if the network problem is at the core, distribution, or access layer of the network. Once this step is complete and the layer is identified, the network engineer can determine which pieces of equipment are the most likely cause.
Voice packets are being received in a continuous stream by an IP phone, but because of network congestion the delay between each packet varies and is causing broken conversations. What term describes the cause of this condition?
buffering
latency
queuing
jitter
jitter
Answers Explanation & Hints:
Jitter is the variation in the latency or delay of received packets. When data is sent, packets are sent in a continuous stream and are spaced evenly apart. Because of network congestion, the delay between each packet can vary instead of remaining constant.
Which queuing algorithm has only a single queue and treats all packets equally?
FIFO
CBWFQ
WFQ
LLQ
FIFO
Answers Explanation & Hints:
FIFO queuing sends packets out an interface in the order that they had arrived and does not make a decision about packet priority. All packets are treated equally.
A network administrator is deploying QoS with the ability to provide a special queue for voice traffic so that voice traffic is forwarded before network traffic in other queues. Which queuing method would be the best choice?
FIFO
WFQ
CBWFQ
LLQ
LLQ
Answers Explanation & Hints:
Low latency queuing (LLQ) allows delay-sensitive data, such as voice traffic, to be defined in a strict priority queue (PQ) and to always be sent first before any packets in any other queue are forwarded.
What are two characteristics of the best-effort QoS model? (Choose two.)
It does not provide a delivery guarantee for packets.
It uses a connection-oriented approach with QoS.
It treats all network packets in the same way.
It allows end hosts to signal their QoS needs to the network.
It provides preferential treatment for voice packets.
It does not provide a delivery guarantee for packets.
It treats all network packets in the same way.
Answers Explanation & Hints:
The best-effort QoS model provides no guarantees and it is commonly used on the Internet. The best-effort QoS model treats all network packets in the same way.
What are two characteristics of voice traffic? (Choose two.)
Dropped voice packets are not retransmitted.
Voice traffic requires at least 384 kbs of bandwidth.
Voice traffic consumes lots of network resources.
Voice traffic is unpredictable and inconsistent.
Voice traffic latency should not exceed 150 ms.
Dropped voice packets are not retransmitted.
Voice traffic latency should not exceed 150 ms.
Answers Explanation & Hints:
Voice traffic does not consume a lot of network resources, such as bandwidth. However, it is very sensitive to delay and dropped packets cannot be retransmitted. For good voice quality, the amount of latency should always be less than 150 milliseconds.
Which type of network traffic cannot be managed using congestion avoidance tools?
TCP
UDP
IP
ICMP
UDP
Answers Explanation & Hints:
Queuing and compression techniques can help to reduce and prevent UDP packet loss, but there is no congestion avoidance for User Datagram Protocol (UDP) based traffic.
When QoS is implemented in a converged network, which two factors can be controlled to improve network performance for real-time traffic? (Choose two.)
link speed delay packet routing jitter packet addressing
delay
jitter
Answers Explanation & Hints:
Delay is the latency between a sending and receiving device. Jitter is the variation in the delay of the received packets. Both delay and jitter need to be controlled in order to support real-time voice and video traffic.
Why is QoS an important issue in a converged network that combines voice, video, and data communications?
Data communications must be given the first priority.
Data communications are sensitive to jitter.
Voice and video communications are more sensitive to latency.
Legacy equipment is unable to transmit voice and video without QoS
Voice and video communications are more sensitive to latency.
Answers Explanation & Hints:
Without any QoS mechanisms in place, time-sensitive packets, such as voice and video, will be dropped with the same frequency as email and web browsing traffic.
A network administrator configures a router with the command sequence:
R1(config)# boot system tftp://c1900-universalk9-mz.SPA.152-4.M3.bin
R1(config)# boot system rom
What is the effect of the command sequence?
On next reboot, the router will load the IOS image from ROM.
The router will copy the IOS image from the TFTP server and then reboot the system.
The router will load IOS from the TFTP server. If the image fails to load, it will load the IOS image from ROM.
The router will search and load a valid IOS image in the sequence of flash, TFTP, and ROM.
The router will load IOS from the TFTP server. If the image fails to load, it will load the IOS image from ROM.
Answers Explanation & Hints:
The boot system command is a global configuration command that allows the user to specify the source for the Cisco IOS Software image to load. In this case, the router is configured to boot from the IOS image that is stored on the TFTP server and will use the ROMmon imagethat is located in the ROM if it fails to locate the TFTP server or fails to load a valid image from the TFTP server.
An administrator wants to replace the configuration file on a Cisco router by loading a new configuration file from a TFTP server. What two things does the administrator need to know before performing this task? (Choose two.)
router IP address
TFTP server IP address
name of the configuration file that is currently stored on the router
name of the configuration file that is stored on the TFTP server
configuration register value
TFTP server IP address
name of the configuration file that is stored on the TFTP server
Answers Explanation & Hints:
In order to identify the exact location of the desired configuration file, the IP address of the TFTP server and the name of the configuration file are essential information. Because the file is a new configuration, the name of the current configuration file is not necessary.
Refer to the exhibit. Which of the three Cisco IOS images shown will load into RAM?
https://infraexam.com/wp-content/uploads/2020/11/CCNA3-v7-%E2%80%93-ENSA-%E2%80%93-Modules-9-%E2%80%93-12-Optimize-Monitor-and-Troubleshoot-Networks-Exam-Answers-04.png
The router selects an image depending on the value of the configuration register.
The router selects the third Cisco IOS image because it is the most recent IOS image.
The router selects the second Cisco IOS image because it is the smallest IOS image.
The router selects an image depending on the boot system command in the configuration.
The router selects the third Cisco IOS image because it contains the advipservicesk9 image.
The router selects an image depending on the boot system command in the configuration.
Answers Explanation & Hints:
When performing an upgrade or testing different IOS versions, the boot system command is used to select which image is used to boot the Cisco device.
Refer to the exhibit. What two types of devices are connected to R1? (Choose two.)
https://infraexam.com/wp-content/uploads/2020/11/CCNA3-v7-%E2%80%93-ENSA-%E2%80%93-Modules-9-%E2%80%93-12-Optimize-Monitor-and-Troubleshoot-Networks-Exam-Answers-02.png
router switch repeater hub Source Route Bridge
router
switch
Answers Explanation & Hints:
The capabilities of the devices displayed by the output show them to be a Cisco 2811 series router, Cisco 1941 series router, and a Cisco 2960 switch.
What are three functions provided by the syslog service? (Choose three.)
to gather logging information for monitoring and troubleshooting
to select the type of logging information that is captured
to specify the destinations of captured messages
to periodically poll agents for data
to provide statistics on packets that are flowing through a Cisco device
to provide traffic analysis
to gather logging information for monitoring and troubleshooting
to select the type of logging information that is captured
to specify the destinations of captured messages
Answers Explanation & Hints:
There are three primary functions provided by the syslog service:
gathering logging information
selection of the type of information to be logged
selection of the destination of the logged information
What is the function of the MIB element as part of a network management system?
to store data about a device
to collect data from SNMP agents
to change configurations on SNMP agents
to send and retrieve network management information
to store data about a device
Answers Explanation & Hints:
The Management Information Base (MIB) resides on a networking device and stores operational data about the device. The SNMP manager can collect information from SNMP agents. The SNMP agent provides access to the information.
