CCNA 3 v6 Chapter 4: Check Your Understanding Questions Answers

CCNA 3 v6.0 (Scaling Networks v6) Chapter 4: EtherChannel and HSRP: Check Your Understanding Questions Answers

1. The trunk link between two 2960 switches has reached its capacity. How can you address this in the most economical way?

Add routers between the switches to create additional broadcast domains.
Bundle physical ports using EtherChannel.
Configure smaller VLANs to decrease the size of the collision domain.
Increase the speed of the ports by using the bandwidth command.

Explanation: Increasing the link speed does not scale very well. Adding more VLANs does not reduce the amount of traffic that is flowing across the link. Inserting a router between the switches does not improve congestion.

2. Which two load-balancing methods can be implemented with EtherChannel technology? (Choose two.)

Destination IP to destination MAC
Destination IP to source IP
Destination MAC to destination IP
Destination MAC to source MAC
Source IP to destination IP
Source MAC to destination MAC

Explanation: Source MAC to destination MAC load balancing and source IP to destination IP load balancing are two implementation methods used in EtherChannel technology.

3. Which statement is true regarding the use of PAgP to create EtherChannels?

It increases the number of ports that are participating in spanning tree.
It is Cisco proprietary.
It mandates that an even number of ports (2, 4, 6, etc.) be used for aggregation.
It requires full duplex.
It requires more physical links than LACP does.

Explanation: PAgP is used to automatically aggregate multiple ports into an EtherChannel bundle, but it works only between Cisco devices. LACP can be used for the same purpose between Cisco and non-Cisco devices. PAgP must have the same duplex mode at both ends and can use two ports or more. The number of ports depends on the switch platform or module. An EtherChannel aggregated link is seen as one port by the spanning-tree algorithm.

4. Which two protocols are link aggregation protocols? (Choose two.)

802.3ad
EtherChannel
PAgP
RSTP
STP

Explanation: The two protocols that can be used to form an EtherChannel are PAgP (Cisco proprietary) and LACP, also known as IEEE 802.3ad. STP (Spanning Tree Protocol) or RSTP (Rapid Spanning Tree Protocol) is used to avoid loops in a Layer 2 network. EtherChannel describes the bundling of two or more links that are treated as a single link for spanning-tree configuration.

5. Which combination of modes establishes an EtherChannel?

Switch 1 set to auto; switch 2 set to auto.
Switch 1 set to auto; switch 2 set to on.
Switch 1 set to desirable; switch 2 set to desirable.
Switch 1 set to on; switch 2 set to desirable

Explanation: Switch 1 and switch 2 establish an EtherChannel if both sides are set to desirable as both sides will negotiate the link. A channel can also be established if both sides are set to on, or if one side is set to auto and the other to desirable. Setting one switch to on prevents that switch from negotiating the formation of an EtherChannel bundle.

6. Which interface configuration command enables a port to initiate an LACP EtherChannel?

channel-group mode active
channel-group mode auto
channel-group mode desirable
channel-group mode on
channel-group mode passive

Explanation: The command channel-group mode active enables LACP unconditionally, and the command channel-group mode passive enables LACP only if the port receives an LACP packet from another device. The command channel-group mode desirable enables PAgP unconditionally, and the command channel-group mode auto enables PAgP only if the port receives a PAgP packet from another device.

7. Which interface configuration command enables a port to establish an EtherChannel only if it receives PAgP packets from the other switch?

channel-group mode active
channel-group mode auto
channel-group mode desirable
channel-group mode on
channel-group mode passive

8. Which statement describes a characteristic of EtherChannel?

It can combine up to a maximum of four physical links.
It can bundle mixed types of 100 Mbps and 1 Gbps Ethernet links.
It consists of multiple parallel links between a switch and a router.
It is made by combining multiple physical links that are seen as one link between two switches.

Explanation: An EtherChannel is formed by combining multiple (same type) Ethernet physical links so they are seen and configured as one logical link. It provides an aggregated link between two switches. Currently each EtherChannel can consist of up to eight compatibly configured Ethernet ports.

9. What are two advantages of using LACP? (Choose two.)

LACP allows automatic formation of EtherChannel links.
LACP allows the use of multivendor devices.
LACP decreases the amount of configuration that is needed on a switch for EtherChannel.
LACP eliminates the need for a spanning-tree protocol.
LACP increases redundancy to Layer 3 devices.
LACP provides a simulated environment for testing link aggregation.

Explanation: LACP is part of an IEEE specification (802.3ad) that enables several physical ports to automatically be bundled to form a single EtherChannel logical channel. LACP allows a switch to negotiate an automatic bundle by sending LACP packets to the peer. It performs a function similar to PAgP with Cisco EtherChannel, but it can be used to facilitate EtherChannels in multivendor environments. Cisco devices support both PAgP and LACP configurations.

10. Which three settings must match in order for switch ports to form an EtherChannel? (Choose three.)

Non-trunk ports must belong to the same VLAN.
Port security violation settings on interconnecting ports must match.
The duplex settings on interconnecting ports must match.
The port channel group number on interconnecting switches must match.
The SNMP community strings must match.
The speed settings on interconnecting ports must match.

Explanation: Speed and duplex settings must match for all interfaces in an EtherChannel. All interfaces in the EtherChannel must be in the same VLAN if the ports are not configured as trunks. Any ports may be used to establish an EtherChannel. SNMP community strings and port security settings are not relevant to EtherChannel.

11. Which statement about HSRP operation is true?

HSRP supports only clear-text authentication.
The active router responds to requests to the virtual MAC address and virtual IP address.
The AVF responds to default gateway ARP requests.
The HSRP virtual IP address must be the same as one of the router’s interface addresses on the LAN.

Explanation: Hosts send traffic to their default gateways, which is the virtual IP address and the virtual MAC address. The virtual IP address is assigned by the administrator, and the virtual MAC address is created automatically by HSRP. The virtual IPv4 and MAC addresses provide consistent default gateway addressing for the end devices. Only the HSRP active router responds to the virtual IP and virtual MAC address.

12. Which statement regarding VRRP is true?

VRRP elects a master router and one or more other routers as backup routers.
VRRP elects a master router and one backup routers, and all other routers are standby routers.
VRRP elects an active router and a standby router, and all other routers are backup routers.
VRRP is a Cisco proprietary protocol.

Explanation: VRRP selects a master router and one or more backup routers. VRRP backup routers monitor the VRRP master router.

13. A network administrator is overseeing the implementation of first-hop redundancy protocols. Which protocol is a Cisco proprietary protocol?

HSRP
IRDP
Proxy ARP
VRRP

Explanation: HSRP and GLBP are Cisco proprietary protocols, and VRRP is an IEEE open standard protocol.

14. What is the purpose of HSRP?

It enables an access port to immediately transition to the forwarding state.
It prevents a rogue switch from becoming the STP root.
It prevents malicious hosts from connecting to trunk ports.
It provides a continuous network connection when a default gateway fails.

Explanation: HSRP is an FHRP that provides Layer 3 default gateway redundancy.