CISCO CCNA Exam – Q23

What are the possible trunking modes for a switch port? (Choose three.)

A. transparent
B. auto
C. on
D. desirable
E. client
F. forwarding

Correct Answer: B, C, D
Section: LAN Switching Technologies

Explanation:
These are the different types of trunk modes:

ON: This mode puts the port into permanent trunk mode and negotiates to convert the link into a trunk link. The port becomes a trunk port even if the adjacent port does not agree to the change.
OFF: This mode puts the port into permanent non-trunk mode and negotiates to convert the link into a non-trunk link. The port becomes a non-trunk port even if the adjacent port does not agree to the change.
Desirable: This mode causes the port to actively attempt to convert the link into a trunk link. The port becomes a trunk port if the adjacent port is set to on, desirable, or auto mode.
Auto: This mode enables the port to convert the link into a trunk link. The port becomes a trunk port if the adjacent port is set to on or desirable mode. This is the default mode for Fast and Gigabit Ethernet ports.
Nonegotiate: This mode puts the port into permanent trunk mode, but does not allow the port to generate Dynamic Trunking Protocol (DTP) frames. The adjacent port must be configured manually as a trunk port to establish a trunk link.

CISCO CCNA Exam – Q22

Which two of these statements regarding RSTP are correct? (Choose two.)

A. RSTP cannot operate with PVST+.
B. RSTP defines new port roles.
C. RSTP defines no new port states.
D. RSTP is a proprietary implementation of IEEE 802.1D STP.
E. RSTP is compatible with the original IEEE 802.1D STP.

Correct Answers: B, E

Explanation:
When network topology changes, rapid spanning tree protocol (IEEE802.1W, referred to as RSTP) will speed up significantly the speed to re-calculate spanning tree. RSTP not only defines the role of other ports: alternative port and backup port, but also defines status of 3 ports: discarding status, learning status, forwarding status.
RSTP is 802.1D standard evolution, not revolution. It retains most of the parameters, and makes no changes.

CISCO CCNA Exam – Q21

Refer to the exhibit.

CISCO CCNA Exam – Q21

Which two statements are true of the interfaces on Switch1? (Choose two.)

A. Multiple devices are connected directly to FastEthernet0/1.
B. A hub is connected directly to FastEthernet0/5.
C. FastEthernet0/1 is connected to a host with multiple network interface cards.
D. FastEthernet0/5 has statically assigned MAC addresses.
E. FastEthernet0/1 is configured as a trunk link.
F. Interface FastEthernet0/2 has been disabled.

Correct Answers: B, E

Explanation:
Carefully observe the information given after command show. Fa0/1 is connected to Switch2, seven MAC addresses correspond to Fa0/1, and these MAC are in different VLAN. From this we know that Fa0/1 is the trunk interface.
From the information given by show cdp neighbors we find that there is no Fa0/5 in CDP neighbor. However, F0/5 corresponds to two MAC addresses in the same VLAN. Thus we know that Fa0/5 is connected to a Hub.
Based on the output shown, there are multiple MAC addresses from different VLANs attached to the FastEthernet 0/1 interface. Only trunks are able to pass information from devices in multiple VLANs.

CISCO CCNA Exam – Q20

Three switches are connected to one another via trunk ports. Assuming the default switch configuration, which switch is elected as the root bridge for the spanning-tree instance of VLAN 1?

A. the switch with the highest MAC address
B. the switch with the lowest MAC address
C. the switch with the highest IP address
D. the switch with the lowest IP address

Correct Answer: B

Explanation:
Each switch in your network will have a Bridge ID Priority value, more commonly referred to as a BID. This BID is a combination of a default priority value and the switch’s MAC address, with the priority value listed first. The lowest BID will win the election process.

For example, if a Cisco switch has the default priority value of 32,768 and a MAC address of 11-22-33-44-55-66, the BID would be 32768:11-22-33-44-55-66. Therefore, if the switch priority is left at the default, the MAC address is the deciding factor in the root bridge election.

CISCO CCNA Exam – Q19

What are three advantages of VLANs? (Choose three.)

A. VLANs establish broadcast domains in switched networks.
B. VLANs utilize packet filtering to enhance network security.
C. VLANs provide a method of conserving IP addresses in large networks.
D. VLANs provide a low-latency internetworking alternative to routed networks.
E. VLANs allow access to network services based on department, not physical location.
F. VLANs can greatly simplify adding, moving, or changing hosts on the network.

Correct Answers: A, E, F
Explanation:
VLAN technology is often used in practice, because it can better control layer2 broadcast to improve network security. This makes network more flexible and scalable.
Packet filtering is a function of firewall instead of VLAN.

CISCO CCNA Exam – Q18

Cisco Catalyst switches CAT1 and CAT2 have a connection between them using ports FA0/13. An 802.1Q trunk is configured between the two switches. On CAT1, VLAN 10 is chosen as native, but on CAT2 the native VLAN is not specified.
What will happen in this scenario?

A. 802.1Q giants frames could saturate the link.
B. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send untagged frames.
C. A native VLAN mismatch error message will appear.
D. VLAN 10 on CAT1 and VLAN 1 on CAT2 will send tagged frames.

Correct Answer: C

Explanation:
A “native VLAN mismatch” error will appear by CDP if there is a native VLAN mismatch on an 802.1Q link. “VLAN mismatch” can cause traffic from one vlan to leak into another vlan.

CISCO CCNA Exam – Q17

Refer to the exhibit.

CISCO CCNA Exam – Q17

A network technician is asked to design a small network with redundancy. The exhibit represents this design, with all hosts configured in the same VLAN. What conclusions can be made about this design?

A. This design will function as intended.
B. Spanning-tree will need to be used.
C. The router will not accept the addressing scheme.
D. The connection between switches should be a trunk.
E. The router interfaces must be encapsulated with the 802.1Q protocol.

Correct Answer: C

Explanation:
Each interface on a router must be in a different network. If two interfaces are in the same network, the router will not accept it and show error when the administrator assigns it.

CISCO CCNA Exam – Q16

Refer to the exhibit.

CISCO CCNA Exam – Q16

A technician is troubleshooting host connectivity issues on the switches. The hosts in VLANs 10 and 15 on Sw11 are unable to communicate with hosts in the same VLANs on Sw12. Hosts in the Admin VLAN are able to communicate. The port-to-VLAN assignments are identical on the two switches. What could be the problem?

A. The Fa0/1 port is not operational on one of the switches.
B. The link connecting the switches has not been configured as a trunk.
C. At least one port needs to be configured in VLAN 1 for VLANs 10 and 15 to be able to communicate.
D. Port FastEthernet 0/1 needs to be configured as an access link on both switches.
E. A router is required for hosts on SW11 in VLANs 10 and 15 to communicate with hosts in the same VLAN on Sw12.

Correct Answer: B

Explanation:
In order for hosts in the same VLAN to communicate with each other over multiple switches, those switches need to be configured as trunks on their connected interfaces so that they can pass traffic from multiple VLANs.

CISCO CCNA Exam – Q15

Refer to the exhibit.

CISCO CCNA Exam – Q15
Given this output for Switch C, what should the network administrator’s next action be?

A. Check the trunk encapsulation mode for Switch C’s fa0/1 port.
B. Check the duplex mode for Switch C’s fa0/1 port.
C. Check the duplex mode for Switch A’s fa0/2 port.
D. Check the trunk encapsulation mode for Switch A’s fa0/2 port.

Correct Answer: C

Explanation:
Here we can see that this port is configured for full duplex, so the next step would be to check the duplex setting of the port on the other switch. A mismatched trunk encapsulation would not result in input errors and CRC errors.

CISCO CCNA Exam – Q14

Refer to the exhibit.
CISCO CCNA Exam – Q14

A network administrator is configuring an EtherChannel between SW1 and SW2. The SW1 configuration is shown. What is the correct configuration for SW2?

A.
interface FastEthernet 0/1
channel-group 1 mode active
switchport trunk encapsulation dot1q
switchport mode trunk
interface FastEthernet 0/2
channel-group 1 mode active
switchport trunk encapsulation dot1q
switchport mode trunk
B.
interface FastEthernet 0/1
channel-group 2 mode auto
switchport trunk encapsulation dot1q
switchport mode trunk
interface FastEthernet 0/2
channel-group 2 mode auto
switchport trunk encapsulation dot1q
switchport mode trunk
C.
interface FastEthernet 0/1
channel-group 1 mode desirable
switchport trunk encapsulation dot1q
switchport mode trunk
interface FastEthernet 0/2
channel-group 1 mode desirable
switchport trunk encapsulation dot1q
switchport mode trunk
D.
interface FastEthernet 0/1
channel-group 1 mode passive
switchport trunk encapsulation dot1q
switchport mode trunk
interface FastEthernet 0/2
channel-group 1 mode passive
switchport trunk encapsulation dot1q
switchport mode trunk

Correct Answer: C

Explanation:
If the EtherChannel was configured with mode “auto”, it was using PAgP, so, we need to configure the other switch with “desirable” mode.
PAgP modes: auto | Desirable
LACP modes: active | pasive