Title: ICND1 / 2. LAN Switching Technologies

Q: On a Cisco 2950 switch, which status LED and color combination indicates a Power On Self Test (POST) failure?
A: system LED: solid amber

Q: On a Cisco 2950 switch, which status LED and color combination indicates that the RPS is installed and operational?
A: Solid Green

Q: On a Cisco 2950 switch, which status LED and color combination indicates that another switch in the stack is being backed up by RPS?
A: Blinking Green

Q: On a Cisco 2950 switch, which status LED and color combination indicates the Switch internal power supply is down and the switch is functioning on the RPS?
A: Blinking Amber

Q: Which switch becomes the root bridge?
A: The switch with the lowest bridge ID is selected as the root bridge. If the same priority number is configured on two or more switches in the network, the switch with the lowest MAC address will become the root.

Q: How would you see the spanning tree information for vlan #34?
A: Switch1#show spanning-tree vlan 34

Q: What will be the effect of executing the following command on port F0/1?
switch(config-if)# switchport port-security mac-address 00C0.35F0.8301
A: The command statically defines the MAC address of 00c0.35F0.8301 as an allowed host on the switch port.

Q: Which of the following technologies should be used to prevent a switching loop if a switch is connected to a port configured for PortFast?
A: BPDU (bridge protocol data unit) Guard prevents switching loops in the case of a switch being connected to a PortFast interface. PortFast is used for ports that connect to host systems, such as workstations and printers, and allows the port to immediately enter a forwarding state. This bypasses the normal 30-second delay that Spanning Tree Protocol would normally use to determine if a switch has been connected to the port. Implementing BPDU Guard will disable the port if a switch is connected and a BPDU is received.

Q: __________ is used to protect the root bridge placement in the Spanning Tree, not to protect PortFast ports.
A: Root Guard

Q: How is the data that crosses an 802.1q trunk link routed to its proper VLAN?
A: Each frame receives a frame tag.
Frame tagging is used when VLAN traffic travels over a trunk link. Trunk links carry frames for multiple VLANs. Therefore, frame tags are used for identification of frames from different VLANs. Inter Switch Link (ISL) and Institute of Electrical and Electronics Engineers (IEEE) 802.1q are the two frame tagging methods supported on Cisco devices.

Q: What command would you use to enable an interface for VLAN 33?
A: SwitchB(config-if)#switchport access vlan 33

Q: Which command would be used to list the timers, version of spanning tree and the bridge ID of the local and designated switch for a specific VLAN on a Cisco Catalyst 2950 series switch?
A: show spanning-tree vlan vlan-id

Q: Which command will display the Virtual LAN (VLAN) frame tagging method for a switch link?
A: The show interfaces trunk command displays the list of trunk ports and the configured VLAN frame tagging methods.
Sample output of the show interfaces trunk command would be as follows:
SwitchB#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Fa0/2 on 802.1q trunking 1
Fa0/3 on 802.1q trunking 1

Q: Which trunk encapsulation defines one VLAN on each trunk as a native VLAN?
A: IEEE 802.1q

Q: The ____________________ feature of Cisco VTP allows switches to dynamically delete or add VLANs to a trunk. It restricts unnecessary traffic, such as broadcasts, to only those switches that have user machines connected for a particular VLAN. It is not required to flood a frame to a neighboring switch if that switch does not have any active ports in the source VLAN. A trunk can also be manually configured with its allowed VLANs, as an alternative to _____________________.
A: VLAN Trunking Protocol (VTP) pruning

Q: The __________________________ feature allows a separate instance of Spanning Tree Protocol (STP) per VLAN. Each VLAN will have its own root switch and, within each VLAN, STP will run and remove loops for that particular VLAN.
A: Per-VLAN Spanning Tree (PVST)

Q: ________________________________ is an Institute of Electrical and Electronics Engineers (IEEE) standard. It reduces high convergence time that was previously required in STP implementations. It is interoperable with STP (802.1d).
A: Rapid Spanning Tree Protocol (RSTP, 802.1w)

Q: 802.1w refers to __________________________.
A: Rapid Spanning Tree Protocol (RSTP).

Q: With _____________, the switch automatically assigns a switch port to a VLAN using information from the user machine, such as its Media Access Control (MAC) address or IP address. The switch then verifies information with a VLAN Membership Policy Server (VMPS) that contains a mapping of user machine information to VLANs.
A: dynamic VLANs

Q: By default, VLANs ___ to ___ are eligible for pruning.
A: 2, 1000

Q: ________________________ is used to remove switching loops in redundantly configured switched environments, and to create a single active Layer 2 path between any two network segments. This eliminates the chance of multiple copies of the same unicast frame being sent in the LAN. It also prevents broadcast packets from creating a broadcast storm when redundant connections exist between the switches. Benefits include:
Prevention of broadcast storms
Prevention of multiple frame copies
Media Access Control (MAC) address database stability
A: Spanning Tree Protocol (STP)

Q: Which switch port will be in a blocking state? (Click the Exhibit(s) button to view the switch port diagram.)
 SwitchA Fa0/1
 SwitchA Fa0/2
 SwitchB Fa0/1
 SwitchB Fa0/2
A: SwitchB will be forwarding on F0/1, and blocking on F0/2.
SwitchA will become the STP root bridge due to its lower MAC address. All ports on the root bridge will become designated ports in a forwarding state. SwitchB has redundant connectivity to the root bridge, and must block one of its interfaces to prevent a switching loop. STP will use its operations to determine which of the redundant interfaces on SwitchB to block to prevent a switching loop
Both interfaces are the same speed (FastEthernet), and thus their cost to the root is the same.
Finally, the interface with the lowest number will become the forwarding port. F0/1 has a lower port number than F0/2, so F0/1 becomes a forwarding port, and F0/2 becomes a blocking port.
Note: Unlike STP, Rapid Spanning Tree Protocol (RSTP) uses the term "discarding" for a switch port that is not forwarding frames

Q: The ______________ switching process only waits to receive the first 64 bytes of the frame before forwarding it the destination port.
______________ internal switching assumes that if there is no error in the first 64 bytes of the data, the frame is error free. The assumption is based on the fact that if a frame suffers a collision, it occurs within the first 64 bytes of data.
______________ forwarding speed lies between that of store and forward and cut-through.
A: fragment-free

Q: How would you assign an IP address and default gateway to a switch?
A: Switch(config)# ip default-gateway 10.0.0.254
Switch(config)# interface vlan1
Switch(config-if)# ip address 10.0.0.1 255.0.0.0
IP addresses are assigned to switches by assigning the address to VLAN 1 using the ip address command, while the default gateway is configured in global configuration mode using the ip default-gateway command. A default gateway is assigned to a Layer 2 switch using the following command syntax, where h.h.h.h is the IP address of the default gateway:

Q: Which of the following protocols allow the root switch location to be optimized per VLAN? (Choose all that apply.)
A: Both Per VLAN Spanning Tree Plus (PVST+) and Per VLAN Rapid Spanning Tree (PVRST) protocols allow for a spanning tree instance for each VLAN, allowing for the location optimization of the root bridge for each VLAN. These are Cisco proprietary enhancements to the 802.1d and 802.1w standards, respectivel

Q: With RSTP hello timers set to the default interval, how quickly can a non-edge port discover that its neighbor is down?
A: 6 seconds
With Rapid Spanning Tree Protocol (RSTP) hello timers set at the default interval, a non-edge port can discover that its neighbor is down in 6 seconds. One of the advantages of RSTP over STP is quicker convergence when changes occur in the topology. After a non-edge port fails to receive three Bridge Protocol Data Units (BPDUs) from its neighbor, it will assume the neighbor to be down and will age out all information regarding the neighbor. Since hellos are sent at 2-second intervals in RSTP, it will take only 6 seconds for this to occur, as compared to 20 seconds for STP.

Q: What port types are available for Rapid Spanning Tree Protocol (RSTP) but NOT available in Spanning Tree Protocol (STP)? (Choose two.)
a. Root port
b. Backup port
c. Alternate port
d. Designated port
e. Learning port
A: b. Backup port
c. Alternate port
RSTP was developed to reduce the high convergence times required in STP, and introduces the alternate port and backup port roles. RSTP is an Institute of Electrical and Electronics Engineers (IEEE) standard, 802.1w, and is interoperable with 802.1d (STP). It operates on the Data Link layer of the OSI model.
An alternate port is a port that has an alternative path or paths to the root bridge, but is currently in a discarding state.
A backup port is a port on a segment that could be used to reach the root port, but there is already an active designated port for the segment. An alternate port can also be described as a secondary, unused root port, and a backup port as a secondary, unused designated port.

Q: When configuring switch port security, two commands are required. One command specifies how many addresses are allowed per switch port and the other tells the switch what to do when a violation occurs. Configuring the first without the second is like creating a rule without enforcing the rule.
What are the commands?
A: switchA(config-if)# switchport port-security maximum 1
switchA(config-if)# switchport port-security violation shutdown

Q: Which command will save a dynamically learned MAC address in the running-configuration of a Cisco switch?
A: Issuing the switchport port-security mac-address sticky command will allow a switch to save a dynamically learned MAC address in the running-configuration of the switch, which prevents the administrator from having to document or configure specific MAC addresses. Once the approved MAC addresses have all been learned, the network administrator simply saves the running-configuration file to NVRAM with the copy running-config startup-config command.

Q: What is the Institute of Electrical and Electronics Engineers (IEEE) specification for Spanning Tree Protocol (STP)?
A: 802.1d

Q: The IEEE 802.1q specification is for ______________________.
A: Virtual LAN (VLAN) trunking

Q: 802.3z is the IEEE specification for _____________.
A: Gigabit Ethernet

Q: What Cisco IOS command produced the following output?
Port Mode Encapsulation Status Native vlan
Fa0/1 on 802.1q trunking 1
Fa0/2 on 802.1q trunking 1
Fa0/3 on 802.1q trunking 1
A: show interface trunk

Q: ___________________ is a Cisco proprietary trunk negotiation protocol and is used to determine if two interfaces on connected devices can become a trunk.
A: Dynamic Trunk Protocol

Q: What are the five modes of Dynamic Trunk Protocol?
A: Trunk: Puts the interface into permanent trunking mode and negotiates to convert the link into a trunk link. The interface becomes a trunk interface even if the neighboring interface does not agree to the change.
Access: Puts the interface into permanent nontrunking mode and negotiates to convert the link into a nontrunk link. The interface becomes a nontrunk interface even if the neighboring interface does not agree to the change.
Dynamic desirable: Makes the interface actively attempt to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode.
Dynamic auto: Makes the interface willing to convert the link to a trunk link. The interface becomes a trunk interface if the neighboring interface is set to trunk or desirable mode. This is the default mode for all Ethernet interfaces in Cisco IOS.
Nonegotiate: Puts the interface into permanent trunking mode but prevents the interface from generating DTP frames. You must configure the neighboring interface manually as a trunk interface to establish a trunk link. Use this mode when connecting to a device that does not support DTP.
If one side's mode of link is in trunk mode, dynamic desirable mode, or dynamic auto mode, and the other side is trunk or dynamic desirable, a trunk will form. Nonegotiate mode enables trunking but disables DTP.

Q: What Cisco IOS command produced the following as a part of its output?
Port Security: Enabled
Port status: SecureUp
Violation mode: Shutdown
Maximum MAC Addresses: 2
Total MAC Addresses: 2
Configured MAC Addresses: 2
Aging Time: 30 mins
Aging Type: Inactivity
SecureStatic address aging: Enabled
Security Violation count: 0
A: show port-security interface fa0/1.
The sample output indicates that port security has been enabled on the interface, and that a maximum of two MAC addresses has been configured. A violation mode of Shutdown indicates that if a third MAC address attempts to make a connection, the switch port will be disabled. It is useful to note that you must specify a port number when you execute the command. In this case, the command was Switch# show port-security interface fastethernet0/1.

Q: Which command would you use to see which interfaces are currently operating as trunks?
A: The show interfaces trunk command displays a list of interfaces currently operating as trunks, and their configuration (such as supported VLANs or frame tagging method). Sample output would resemble the following:
Switch# show interfaces trunk
Port Mode Encapsulation Status Native vlan
Gi0/1 desirable 802.1q trunking 1
Gi0/2 desirable 802.1q trunking 1
Port Vlans allowed on trunk
Gi0/1 1-4094
Gi0/2 1-4094

Q: Which of the following technologies allows a switch port to immediately transition to a forwarding state?
A: PortFast is a technology that allows a switch port connected to an end node such as a workstation, server, or printer to bypass the normal Spanning Tree Protocol (STP) convergence process. When a new device is powered up on a switch port, it will immediately transition to a forwarding state.

Q: On Cisco switches, what is the correct order of port transition through the Spanning Tree Protocol (STP) states?
a. learning, listening, blocking, forwarding
b. listening, blocking, forwarding, learning
c. blocking, learning, forwarding, listening
d. blocking, listening, learning, forwarding
A: d. blocking, listening, learning, forwarding
There are five states in STP transition:
Blocking
Listening
Learning
Forwarding
Disabled
After STP initialization, a port moves from blocking to listening, then to learning, and finally into forwarding state. In case of any errors or exceptions, a port may enter into a disabled state directly from any of the other four states. Once STP has fully converged, all port on all switches will be in either a forwarding state or a blocking state. All other port states are transitioning states between blocking and forwarding.
When STP is initialized, all ports start in the blocking state to prevent bridge loops. If a switch determines that a blocking port must transition to a forwarding state, the blocked port will first move into a listening state, where it begins sending Bridge Protocol Data Units (BPDUs). Next, the port will transition to a learning state, which allows it to populate its Media Access Control (MAC) address table with addresses learned on the port, but it does not yet forward data frames. Finally, it moves into the forwarding state, where the port is capable of sending and receiving data. The switch only learns MAC addresses during the learning and forwarding states.

Q: What are the three RSTP port states? (Choose three.)
A: Rapid Spanning Tree Protocol (RSTP) uses only three port states:
discarding
learning
forwarding
The learning and forwarding states are the same as the original STP standard, but the discarding state performs the functions originally performed in the disabled, blocking, and listening STP states

Q: The ___________________________ command enables a switch (or a router) to copy configuration from NVRAM to its RAM. The configuration file located in NVRAM is referred to as the startup configuration, and a configuration currently loaded and running in RAM is referred to as the running configuration.
A: copy startup-config running-config

Q: What command would you run to determine which switch is the root bridge for a particular VLAN?
A: The show spanning-tree vlan command provides Spanning Tree Protocol (STP) information on the root switch, including the bridge ID, root path, and root cost, as well as information on the local switch. The output of the command is as follows:
Switch# show spanning-tree vlan 1
VLAN0001
Spanning tree enabled protocol ieee
Root ID      Priority      0
Address      000c.00d3.5124
Cost           19
Port           2 (FastEthernet0/2)
Hello Time      2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 000c.14f5.b5c0
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface      Role      Sts      Cost      Prio.Nbr      Type
--------- ---- --- ---- -------- --------------
Fa0/2      Root      FWD      19      128.2      P2p
Fa0/10      Desg      FWD      19      128.10      P2p
Fa0/1      Altn      BLK      19     128.1      P2p

Q: What is the easiest way to force a specific switch to become the spanning-tree root bridge for a VLAN?
A: The spanning-tree root bridge is the bridge with the lowest bridge ID. The bridge ID is a value calculated from the bridge priority and the bridge MAC address. Therefore, lowering the bridge-priority value lowers the bridge ID, which can force the switch to become the root bridge.

Q: Which command is used on a Catalyst 2950 series switch to enable basic port security on the interface?
A: switchport port-security

Q: Based on the output of the show mac-address-table command shown below, where will the switch that produced this output send a frame with a destination MAC address of ffff.ffff.ffff?
Vlan Mac address Type Ports
<output omitted>
1 000f.e544.c2b3 dynamic Fa0/10
1 000d.4589.00b8 dynamic Fa0/5
1 00bd.000b.005bb dynamic Fa0/8
1 0001.0d44.bbdb dynamic Fa0/12
1 0014.0bd4.0054 dynamic Fa0/15
1 00bb.224b.0ac5 dynamic Fa0/1
A: The MAC address ffff.ffff.ffff is called the Layer 2 broadcast address. It will be sent to all ports listed in the table, or known to the switch, as well as to all those unlisted, or not yet known by the switch. This excludes the originating port only.

Q: Which command will let you see the current operating mode for a switch port?
A: The show interfaces switchport command is used to verify the operational and configured status of a switch port. The output of the command is follows:
switch# show interfaces fastethernet0/1 switchport
Name: Fa0/1
Switchport: Enabled
Administrative Mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: Off
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none

Q: The _______________ command is used to view hardware-related information on router and switch interfaces. It is useful for troubleshooting and diagnosing issues with interfaces.
A: show controllers

Q: Which Cisco 2950 switch command or set of commands would be used to create a Virtual LAN (VLAN) named MARKETING with a VLAN number of 25?
A: switch(config)# vlan 25
switch(config-vlan)# name MARKETING
The steps to add anew VLAN are as follows:
Create the new VLAN
Name the VLAN
Add the desired ports to the VLAN

Q: How big is the VTP Tag?
A: 4 bytes

Q: Which parameter is used by a switch in a Spanning Tree Protocol (STP) environment to decide its root port?
A: cost values in the received hello messages

Q: Which show command is used to display the status of port security on the specified interface of a Catalyst switch?
A: show port-security interface fastEthernet0/1

Q: What is the default time a port takes to transit from blocking through forwarding during normal operation of Spanning Tree Protocol (STP)?
A: up to 50 seconds

Q: What are the two parameters used by Spanning Tree Protocol (STP) to calculate bridge ID of a switch?
A: 2-byte Priority and a 6-byte MAC address of the switch

Q: What will be the result of this command?
mac-address-table static abcd.ef12.3456 vlan 2 interface fa0/2
A: The MAC address no longer needs to be learned using ARP
The MAC address will be listed in the MAC table for only the given interface

Q: How would you allow VLAN 3 over a trunk already configured to allow multiple other VLANs?
A: SW1(config-if)#switchport trunk allowed vlan add 3

Q: A runt frame is an Ethernet frame that is less than the IEEE 802.3's minimum length of ___ bytes. Runt frames are most commonly caused by collisions; other possible causes are underruns, a bad network card, or software bugs.
A: 64

Q: A jumbo/giant frame is an Ethernet frame with a payload greater than the standard maximum transmission unit (MTU) of _____ bytes. Jumbo frames are used on local area networks that support at least 1 Gbps and can be as large as 9,000 bytes.
A: 1500