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Exam Implementing Cisco IP Switched Networks (SWITCH v2.0)
Number 300-115
File Name Cisco.Braindumps.300-115.2017-09-22.1e.65q.vcex
Size 1.74 Mb
Posted September 22, 2017
Downloads 58
Download Cisco.Braindumps.300-115.2017-09-22.1e.65q.vcex

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Demo Questions

Question 1

Which of the following statements best describes the result of issuing the instance 3 vlans 7 command?

  • A: VLAN 7 is mapped to MST instance 3.
  • B: VLAN 7 is mapped to switchport 3.
  • C: VLAN 7 is mapped to three MST instances.
  • D: Seven VLANs are mapped to MST instance 3.

Correct Answer: A

When the instance 3 vlans 7 command is issued, the virtual local area network (VLAN) 7 is mapped to Multiple Spanning Tree (MST) Protocol instance 3. MST, which is defined by the 802.1s standard, maps a distinct group of VLANs to one STP instance. Multiple STP instances can be used with MST. The Cisco implementation of MST supports 256 instances. However, each instance must support a different group of VLANs because each VLAN can only be mapped to one instance. 
To map one or more VLANs to an MST instance, issue the instance instance-ID vlans vlan-range command, where ID is the number of the MST instance and vlan-range is the VLAN or VLANs that should be mapped to the instance. For example, the command instance 1 vlans 14-16,99 maps VLANs 14 through 16 and VLAN 99 to MST instance 1. 
The instance 3 vlans 7 command will not map VLAN 7 to switchport 3. The instance vlans command cannot be used to map multiple instances to a single VLAN. 
Each VLAN can only be mapped to one instance. When the instance 3 vlans 7 command is issued, only a single VLAN will be mapped to MST instance 3. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify spanning tree 
References:
Cisco IOS LAN Switching Command Reference > bridge-domain through instance (VLAN) > instance (VLAN) 
Cisco > Support > Technology Support > LAN Switching > Spanning Tree Protocol > Technology Information > Technology White Paper > Understanding Multiple Spanning Tree Protocol (802.1s) > Document ID: 24248




Question 2

Which IOS commands are entered in interface configuration mode to configure a switch port to actively negotiate to be an 802.1Q trunk port? (Choose two.) 

  • A: switchport trunk dot1q
  • B: switchport mode dynamic auto
  • C: switchport trunk allowed vlan
  • D: switchport mode trunk
  • E: switchport trunk encapsulation dot1q

Correct Answer: DE

Entering the IOS commands switchport mode trunk and switchport trunk encapsulation dot1q in interface configuration mode will allow a switch port to actively negotiate to be an 802.1Q trunk port. This allows Dynamic Trunking Protocol (DTP) to actively negotiate to be a trunk if the other side is set to trunk, desirable, or auto. 
Use the following steps to configure a port as an 802.1Q trunk:
1. Enter the interface configuration. 
switch(config)# interface interface-id 
2. Configure the port to use 802.1Q encapsulation. 
switch(config-if)# switchport trunk encapsulation dot1q 
3. Configure the port as a trunk port. 
switch(config-if)# switchport mode trunk 
Note: Trunking modes can be configured as dynamic desirable, dynamic auto, trunk, access, and nonegotiate. If both sides are set to auto, no negotiations willoccur. 
Verification of the configuration can be done by executing the show run command on both switches. An example partial output for two switches is shown below:

 

In the above partial output, the following can be determined:
Since it is configured as dynamic desirable, SwitchB will send DTP packets to SwitchA 
Since the two switches are set to dynamic desirable and dynamic auto, they will form a trunk. When one end is set to desirable, the other must be set to trunk, desirable, or auto for a trunk link to form. 
The native VLAN for SwitchA is VLAN 5 as indicated in the last line of its output. SwitchB is set to the default, which is VLAN 1. This configuration would result in a failure of the switches to form a trunk since the native VLANs do not match. 
The switchport allowed vlan command is also valid for configuring dot1q trunks, but is not required. By default, all VLANs are allowed on the trunk. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify trunking 
References:
Cisco IOS Master Command List, Release 12.4T>switchport mode




Question 3

Which of the following standards describes the details of RSTP?

  • A: 802.1d
  • B: 802.1w
  • C: 802.1s
  • D: 802.1x

Correct Answer: B

Rapid Spanning Tree Protocol (RSTP) is described in the IEEE 802.1w standard. It has several enhancements over Spanning Tree Protocol (STP), which uses 802.1d. The result of these enchantments is a more rapid convergence when topology changes occur. The two protocols can coexist in the network. 
If a switch running RSTP receives an 802.1d Bridge Protocol Data Unit (BPDU), on a port it will begin to use 802.1d rules on that port. However, the IEEE 802.1d standard describes STP and not RSTP. 
The IEEE 802.1s standard describes Multiple Spanning Tree Protocol (MST). This enhancement allows for multiple instances of STP. Unlike Common Spanning Tree Protocol (802.1q) and Per-VLAN Spanning Tree Protocol Plus (PVST+), which allow for a single instance of STP or an instance for every VLAN, respectively, MST allows the administrator to map several VLANs to the same instance, without committing them all to the same instance. 
IEEE 802.1x describes a standard for port-based access control. It is not related to VLANs or their management. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify spanning tree 
References:
Cisco > Home > Support > Technology Support > LAN Switching > Spanning Tree Protocol > Technology Information > Technology White Paper > Understanding Rapid Spanning Tree Protocol (802.1w)




Question 4

The following commands have been issued on a Catalyst switch:

 
Which of the following VLANs is allowed on the trunk?

  • A: VLAN 1 and VLANs 101 through 200
  • B: VLANs 101 through 200
  • C: VLANs 1 through 3000
  • D: VLANs 1 through 4094 

Correct Answer: A

Virtual local area network (VLAN) 1 and VLANs 101 through 200 are allowed on the trunk. The switchport trunk allowed vlan command configures a trunk to carry one or more VLANs. The syntax for the switchport trunk allowed vlan command is switchport trunk allowed vlan {vlan-list | all | {add | except | remove} vlan-list}. 
VLANs specified in the vlan-list parameter should be separated by commas. However, if a contiguous group of VLANs is specified, the starting and ending VLAN numbers can be separated by a hyphen. 
If no keywords are specified with the switchport trunk allowed vlan command, then only the VLANs contained within the vlan-list parameter will be allowed on the trunk. The all keyword specifies that all VLANs from 1 through 4094 should be allowed on the trunk. The add keyword specifies the VLANs that should be added to the list of VLANs that are already allowed by the trunk. The except keyword specifies that all VLANs from 1 through 4094 are allowed except the listed VLANs. The remove keyword specifies the VLANs that should be removed from the list of VLANs that are already allowed by the trunk. 
In this scenario, the first command issued is switchport trunk allowed vlan all, which allows VLANs 1 through 4094. The second command issued is switchport trunk allowed vlan remove 1,101-4094, which removes VLAN 1 and VLANs 101-4094. Therefore, VLANs 2 through 100 are allowed. The third command issued is switchport trunk allowed vlan except 3001-4094, which specifies that all VLANs should be allowed except VLANs 3001 through 4094. Therefore, VLANs 1 through 3000 are allowed. The fourth command issued is switchport trunk allowed vlan 1, which specifies that only VLAN 1 should be allowed. The fifth command issued is switchport trunk allowed vlan add 101-200, which adds VLANs 101 through 200 to the list of allowed VLANs. Therefore, VLAN 1 and VLANs 101 through 200 are allowed on the trunk. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify trunking 
References:
Cisco > Cisco IOS Interface and Hardware Component Command Reference > squelch through system jumbomtu > switchport trunk




Question 5

How long does it take for a port to transition from the STP blocking state to the forwarding state by default?

  • A: 2 seconds
  • B: 10 seconds
  • C: 25 seconds
  • D: 50 seconds
  • E: 70 seconds 

Correct Answer: D

It usually takes 50 seconds for a port to transition from the blocking state to the forwarding state in STP. This delay is a function of the default settings for the forward-delay and max-age settings. The max-age delay is 20 seconds by default, and is used to transition from the blocking to the listening state. The forward-delay setting is 15 seconds by default. This timer is used in the transition from the listening to learning states, and again for the transition from the learning to the forwarding state. These timers give STP time to gather the correct information about the network topology. While they can be modified to make convergence more efficient, the default settings work for most networks. To change the timers on all switches in the VTP domain, change the timer settings on the root bridge and the changes will be forwarded to the other switches. 
To prevent switching loops, spanning tree transitions each port through several states whenever there is a change in the network topology. Each state is briefly defined as follows:
Blocking: In the blocking state, a port does not forward frames, learn information, or send information. A forwarding port is placed in the blocked state when the port senses an absence of BPDUs, which are sent in the interval defined by the hello timer (two seconds by default). If the blocked port does not detect a BPDU for the length of time defined in the max-age setting (20 seconds by default), the port will transition into the listening state. 
Listening: In the listening state, a port receives traffic but does not send information. This is the first transitional state after the blocking state. No user data is forwarded at this time, but the switch is very busy. It is during this stage that the switch participates in the election of the root bridge, the designation of root ports on the non-root bridges, and the selection of designated ports on each segment. Ports that are designated or root ports will transition to the learning state after the time defined in the forward delay (15 seconds by default) has elapsed. 
Learning: In the learning state, a switch port can add the MAC addresses that it has learned into its address table, but cannot forward user data. The switch port will remain in this state until the amount of time defined in the forward-delay setting has elapsed (15 seconds by default), at which time it will transition into the forwarding state. 
Forwarding: In the forwarding state, a port is actively forwarding packets. It will remain in the forwarding state until it does not detect a BPDU within the defined hello time, at which time the port is placed in the blocking state and the process starts again. 
NOTE: One of the issues that can adversely affect the operation of STP is a duplex mismatch between the NICs on either end of a link between two switches. While this causes more of a performance problem than a loss of the link, the intermittent nature of the outage can cause one of the other links on the switch to transition into a forwarding state, as it may interpret this as a loss of connectivity. If one of the other links switches to forwarding and the link with the duplex mismatch comes back online (which could happen quickly), it can create a switching loop. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify spanning tree 
References:
Cisco > Support > Technology Support > LAN Switching > Spanning Tree Protocol > Design > Design Technotes > Understanding and Tuning Spanning Tree Protocol Timers > Document ID: 19120
Cisco > Support > Technology Support > LAN Switching > Spanning Tree Protocol > Design > Design Technotes > Spanning Tree Protocol Problems and Related Design Considerations > Document ID: 10566




Question 6

Which of the following is true about CDP?

  • A: It can be used to discover the network topology
  • B: It is used to generate a denial of service attack
  • C: It can be used as part of a MAC address flooding attack
  • D: It is used to generate a MAC spoofing attack

Correct Answer: A

Cisco Discovery Protocol (CDP) is a Cisco proprietary protocol used by Cisco devices to obtain information about directly connected devices that are also made by Cisco. Since this information includes name, device type and capabilities, IP address, and other identifying information, if these packets are captured they can be used to map the network topology. Since the first step in the hacking process (Discovery, Penetration, and Control) is discovery, this can be a security threat. 
CDP is not used to generate a DoS (denial-of-service) attack, which is an attack designed to overwhelm a device with work requests that make it unavailable for its normal jobs. 
CDP is not used as part of a MAC address flooding attack. This is performed by a hacker creating packets with unique MAC addresses and flooding the switch's CAM table with these packets. When the CAM buffer is full, the switch will start sending packets out all interfaces enabling the hacker to capture packets from all switch ports, which is normally not possible on a switch, where each port is its own collision domain. CDP plays no role in this process. 
CDP is not used to generate a MAC spoofing attack. This type of attack involves the creation of a packet using the MAC address of a known host in the network for the purpose of redirecting traffic to the hacker's machine instead. CDP plays no role in this process. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify Layer 2 protocols 
References:
Cisco > Catalyst 4500 Series Switch Cisco IOS Software Configuration Guide, 12.2(37)SG > Configuring CDP




Question 7

Which of the following commands configures a port with a VLAN?

  • A: vlan
  • B: vlan database
  • C: switchport access vlan
  • D: switchport mode access

Correct Answer: C

The switchport access vlan command configures a port with a virtual local area network (VLAN). The syntax for the switchport access vlan command is as follows:
switchport access vlan {vlan-id | dynamic} 
If the vlan-id parameter is specified, then a static VLAN will be configured. If the dynamic keyword is specified, then dynamic VLAN assignment by a VLAN Membership Policy Server (VMPS) will occur. Static VLAN configuration is easy to configure, secure and works well in networks where moves, additions, and changes are rare. In environments where this not the case, dynamic VLANs may be preferable. 
The vlan command is used to add VLANs to the VLAN database and to configure VLAN settings. 
The vlan database command is issued to enter VLAN configuration mode. The following commands can be issued from VLAN configuration mode:
abort - exits without applying changes 
apply - applies changes and bumps the revision number 
exit - applies changes, bumps the revision number and exits VLAN configuration mode 
no - negates a command 
reset - discards changes and rereads the VLAN database 
show - displays information 
vlan - configures the VLAN database 
vtp - configures VLAN Trunking Protocol (VTP) settings 
The switchport mode access command disables trunking for a port. The syntax for the switchport mode command is as follows:
switchport mode {access | trunk | dynamicdesirable | dynamicauto} 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify VLANs 
References:
Cisco > Cisco IOS Interface and Hardware Component Command Reference > squelch through system jumbomtu > switchport access




Question 8

A new switch that contains a configuration consisting of only VLAN 5 was just added to the network. Now users assigned to VLANs 9 and 10 are complaining of communication problems. 
Using the show vlan command, you discover that only VLAN 5 and the default VLANs exist on all your switches. 
What could have caused this problem? 

  • A: The new switch had the default password set.
  • B: The domain name on the new switch did not match the rest of the network.
  • C: The new switch was configured in server mode and the revision number was lower than the current number in the network.
  • D: The new switch was configured in server mode and the revision number was higher than the current number in the network.
  • E: The new switch was configured in transparent mode and the revision number was higher than the current number in the network.

Correct Answer: D

Adding a switch that is configured in VTP server mode and has a revision number higher than the current number in the network could cause the communication problem in the scenario. If the new switch was configured in server mode and the revision number was higher than the revision number on existing switches, it could cause the rest of the switches to update with the information contained in that new advertisement. 
VTP advertisements are flooded throughout the management domain every five minutes or whenever a change occurs in the network. These advertisements are originated from a switch that is in server mode, and are propagated by switches that are in either client or transparent mode. Before a client or another server accepts or incorporates the information sent in the advertisement, it checks the domain name and password (if defined) against its own configuration. Next, the revision number is checked to see if it is higher than the last value stored in the receiving switch. If the revision number is higher, the receiving switch will overwrite its VLAN database with the information in the advertisement. 
A VTP switch in transparent mode will receive and forward VTP advertisements. It will not use the contents of the advertisement to synchronize with its own VLAN database. 
The password, domain name, and VTP mode will not cause the switch to overwrite the other switches. This is a revision number issue. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify VLANs 
References:
Cisco > Home > Support > Technology Support > LAN Switching > Virtual LANS/VLAN Trunking Protocol (VLANS/VTP) > Design > Design Technotes > Understanding VLAN Trunk Protocol (VTP)




Question 9

Which IOS commands should you enter in interface configuration mode to configure a switch port as an access port and assign it to VLAN 25? (Choose two.)

  • A: trunk on
  • B: switchport mode access
  • C: vlan-membership static 25
  • D: switchport access vlan 25

Correct Answer: BD

Use the following steps to assign ports to a VLAN:
1. Enter the interface to be added to the VLAN. 
switch(config)# interface interface-id 
2. Configure the port as a Layer 2 access port. 
switch(config-if)# switchport mode access 
3. Assign the port to a VLAN. 
<fon 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify VLANs 
References:
Cisco > Cisco IOS Interface and Hardware Component Command Reference > switchport access vlan




Question 10

What Cisco switch feature allows IP phones to be automatically placed into a separate VLAN from data traffic?

  • A: marking
  • B: AutoQoS
  • C: private VLANs
  • D: auxiliary VLANs

Correct Answer: D

Auxiliary VLANs allows IP phones to be automatically placed into a separate VLAN from data traffic. The information the phones need regarding this voice VLAN is provided by the switch. This allows the data and voice traffic to use the same physical topology but remain logically separate. The following is an example of the commands that should be executed on the switch to instruct it to provide this information to the IP phone by CDP:
Switch> (enable) set port auxiliaryvlan 2/1-3 222 
This command creates the auxiliary VLAN 222 and adds ports 2/1 to 2/3 to the VLAN. 
Private VLANs are not used for voice traffic. Private VLANs are secondary VLANs created by an administrator that are not accessible by other secondary VLANs. 
Marking is the process of setting the Class of Service (CoS), IP precedence, or DSCP of a packet to a specific value that will provide appropriate QoS throughout the network. It is not involved in separating voice and data traffic. 
Auto QoS is a method of configuring commonly used QoS features on a Cisco switch with a single command. It is not involved in separating voice and data traffic. 
Objective:
Layer 2 Technologies 
Sub-Objective:
Configure and verify VLANs 
References:
Cisco > Catalyst 4500 Series Software Configuration Guide, 8.1 > Configuring VLANs > Configuring Auxiliary VLANs










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