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Exam Implementing Cisco IP Switched Networks (SWITCH v2.0)
Number 300-115
File Name Cisco.Pass4sure.300-115.v1-0.2017-09-25.1e.75q.vcex
Size 2.36 Mb
Posted September 25, 2017
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Download Cisco.Pass4sure.300-115.v1-0.2017-09-25.1e.75q.vcex

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Demo Questions

Question 1

What command should you use to quickly view the HSRP state of the switch for all HSRP groups of which the switch is a member?

  • A: switch# show standby brief
  • B: switch# show ip interface brief
  • C: switch# show hsrp
  • D: switch# show standby

Correct Answer: A

The command show standby brief should be used to quickly view the HSRP state of a switch for all HSRP groups of which it is a member. The summary information it provides includes the group number, priority, state, active device address, standby address, and group address. 
The command show standby can be used to display detailed information about HSRP groups of which a switch is a member. This command would not provide a quick view. This command displays information about HSRP on all configured interfaces and for all HSRP groups. It also displays hello timer information and the expiration timer for the standby switch. 
The command show ip interface brief is useful in that lists the interfaces and displays the basic IP configuration of each. This output would include the IP address of the interface and the state of the interface, but now HSRP information. 
The command show hsrp is not a valid command due to incorrect syntax. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco > Cisco IOS IP Application Services Command Reference > show standby 
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring HSRP




Question 2

Examine the configuration shown below in a partial output of the show run command executed from Router 5.  

 
With this configuration, which of the following is true? 

  • A: if POS 1/0 goes down, Router 5 will become the AVG.
  • B: if POS 1/0 goes down, Router 5 will relinquish its role as AVG.
  • C: if POS 1/0 and POS 2/0 go down, Router 5 will relinquish its role as AVG.
  • D: if POS 1/0 and POS 2/0 go down, Router 5 will become the AVG.

Correct Answer: C

If POS 1/0 and POS 2/0 go down, Router 5 will relinquish its role as active virtual gateway (AVG). The example indicates that Router 5 is configured a member of Gateway Load Balancing Protocol (GLBP) group 156 and that it is tracking the state of two of interfaces, POS 1/0 and 2/0. An initial weighting value of 120 has been assigned to the router in line 4, and upper and lower thresholds of 95 and 110 have been configured, respectively. 
In lines 5 and 6, decrement values of 20 and 10 have assigned to the tracking of interface POS 1/0 and POS2/0, respectively. If either of the tracked interfaces goes down, the weight value of the router will be decreased by the amount of the decrement value. If the weight falls below the lower threshold (95), the router will relinquish its role as the AVG. If either single interface that is being tracked goes down, the weight value will not fall below the lower threshold, and the router will maintain its role of AVG. This occurs because 120 - 20 = 100, which is higher than 95 (the lowest threshold), and 120 - 10 = 110, which is also higher than 95. If both interfaces go down, the value will fall below the lower threshold (120 - 10 - 20 = 90, which is lower than 95), and the router will give up its role as the AVG. 
The loss of interfaces will never cause a router to become the AVG. That can only occur if the router functioning as the current AVG in the group loses its interfaces. 
The loss of either of the interfaces alone will not decrement the initial weighting value enough for it to fall below the lower threshold, and therefore will not cause the router to relinquish its role as AVG. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco > Home > End-of-Sale and End-of-Life Products > Cisco IOS Software Releases > 12.2T > Product Literature > White Papers > GLBP - Gateway Load Balancing Protocol 
Cisco > Cisco IOS IP Application Services Command Reference > threshold metric through weight (real server) > track




Question 3

You need to create an implementation plan for providing Layer 3 redundancy in your switched network. You included Hot Standby Routing Protocol (HSRP) as the protocol to avoid first-hop router failure. However, your supervisor suggests including Virtual Router Redundancy Protocol (VRRP) instead of HSRP in the implementation plan. 
Which of the following statements is TRUE about the reasons for the suggested change in the implementation plan? (Choose two.)

  • A: HSRP works only on Cisco routers and VRRP works on both Cisco and non- Cisco routers.
  • B: HSRP works on both Cisco and non-Cisco routers and VRRP works only Cisco routers.
  • C: HSRP-enabled routers need to be configured manually to preempt the active router and VRRP-enabled routers preempt it automatically.
  • D: HSRP-enabled routers automatically preempt the active router and VRRP-enabled routers need to be configured manually to preempt the active router.

Correct Answer: AC

The following two statements are TRUE:
HSRP works only on Cisco routers and VRRP works on both Cisco and non- Cisco routers. 
HSRP-enabled routers need to be configured manually to preempt the active router and VRRP-enabled routers preempt it automatically. 
HSRP was developed by Cisco intended for only Cisco routers and VRRP was developed by IEFT intended as a standard for routers. HSRP was defined in RFC 2281 and VRRP was defined in RFC 2338. Both these protocols provide a fault tolerance solution by grouping several routers together but presenting them as a single router. One of the routers in the group acts as the active or master router. A second router is selected as the standby router. In case the active or master router fails, the standby router takes over the responsibilities of the active router. 
The router with the highest priority is automatically selected as the active or master router. In HSRP, preempt settings have to be manually configured on every router in the group, even if the routers have a priority higher than that of the active router. However, in VRRP, the routers with higher priority automatically preempt the master router. Another advantage that VRRP has over HSRP is a faster Hello timer (1 second). HSRP has a Hello timer of 3 seconds Two other protocols ICMP Router Discovery Protocol (IRDP) and Gateway Load Balancing Protocol (GLBP) provide redundancy for first-hop router failure. IRDP also allows the selection of a new router if the active router fails, while GLBP provides load balancing in addition to redundancy. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Home > Articles > Cisco Certification > CCDP > CCDP Self Study: Designing High-Availability Services
Cisco First Hop Redundancy Protocols Configuration Guide, Cisco Release 15MT




Question 4

In which HSRP state is the router a candidate to become the next active router for the group?

  • A: Learn
  • B: Backup
  • C: Listen
  • D: Initial
  • E: Standby

Correct Answer: E

The HSRP router in standby state (the standby router) is a candidate to become the next active HSRP router should the current active router fail. 
The six HSRP states are defined as follows:
Initial state: All routers start in this state.
Learn state: The router is in the learn state when it has not communicated with the active router. It does not know which router is the active router and does not know the IP address of the virtual router (if no HSRP IP address configured in the router). 
Listen state: Once the router hears from the active router and knows the virtual IP address, it enters the listen state. It is not the active or standby router.
Speak state: After a router learns the IP address of the virtual router, it enters the speak state. It participates in the active and standby router election. It sends hello messages to the active router. 
Standby state: When the active router has been elected, the second router enters the standby state. This is the standby router and it will become the active router if the active router fails. 
Active state: The router is in active state when it is forwarding packets. It receives packets via the virtual IP address.
Backup is not a valid HSRP router state. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Internetworking Case Studies > Using HSRP for Fault-Tolerant IP Routing 
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring HSRP




Question 5

How is load balancing achieved when implementing HSRP?

  • A: By configuring multiple gateways on the routers
  • B: By using multiple HSRP groups
  • C: By configuring the same priority on all HSRP group members
  • D: By configuring multiple virtual router addresses

Correct Answer: B

When implementing Hot Standby Router Protocol (HSRP), load balancing is achieved by using multiple HSRP groups. Routers configured for HSRP can belong to multiple groups and multiple VLANs. By configuring one group to be active for Router A and standby for Router B, and the second group to be active for Router B and standby for Router A, both routers A and B can be used to pass traffic, as opposed to one sitting idle. 
Load balancing cannot be achieved by configuring multiple gateways on the routers. The routers have one IP address. Each group will have a virtual IP address. In the configuration below, line 4 configures the virtual IP address, and is therefore the address that clients will use as their gateway:
interface fastethernet 0/1 
no switchport 
ip address 192.168.5.5 255.2555.255.0 
standby 1 ip 192.168.5.10 
Load balancing cannot be achieved by configuring the same priority on all HSRP group members. If that were done, one of the routers would become active and the others would remain inactive standbys. The active router will be the one with the highest IP address. 
Load balancing cannot be achieved by configuring multiple virtual router addresses. Each HSRP group can only have one virtual address. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Internetworking Case Studies > Using HSRP for Fault-Tolerant IP Routing




Question 6

Which routers comprise a VRRP group?

  • A: Host and client
  • B: Master and backup
  • C: Active and standby
  • D: Primary and secondary

Correct Answer: B

Virtual Router Redundancy Protocol (VRRP) enables a group of routers to form a single virtual router, known as a VRRP group. Routers are configured in VRRP groups to provide redundancy for a virtual IP address shared among members of the VRRP group. Each group is comprised of a master router and one or more backup routers. The physical IP address of the master router will be the virtual IP address of the group. 
The master router is responsible for forwarding packets sent to the virtual router. The backup routers provide redundancy and stand ready to assume the role of the master router in the event that the master is unable to forward packets. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring VRRP




Question 7

Which of the following is required to allow load balancing between three HSRP routers connected to the same LAN?

  • A: A single HSRP group with all three routers as active routers for the group
  • B: A single HSRP group with one active router for the group
  • C: Two HSRP groups, each with an active router
  • D: Two HSRP groups with one active router for both the groups
  • E: Three HSRP groups, each with an active router
  • F: Three HSRP groups with one active router for all groups

Correct Answer: E

You should configure three HSRP groups on all three routers and select an active router for each of the groups. You can create up to 256 (0 to 255) groups. Each router should be the active router for one of the three groups and the standby router for the remaining two groups. 
If you want to use HSRP on a Layer 3 switch, the switch ports must be one of the following:
EtherChannel port Refers to a Layer 3 switch port used for EtherChannel 
Routed port Refers to a Layer 3 port on a switch used for routing and for inter-VLAN routing 
Switch virtual interface (SVI) Refers to a Layer 2 switch port used for inter-VLAN routing 
Routed ports are the physical Layer 3 interfaces that allow you to configure a switch as a router. The no switchport command allows the port to be used purely as a Layer 3 port. SVIs are Layer 3 logical interfaces of a switch that allow you to enable inter-VLAN routing on Layer 3 switches. An SVI is configured as a VLAN interface and has at least one physical interface assigned to the VLANs. 
Creating a single HSRP group with all three routers as active routers for the group is incorrect. An HSRP group cannot have multiple active routers; it can have only one active router at a time. 
Creating a single HSRP group with one active router for the group is incorrect because it does not allow load balancing between the three routers. All traffic will be passed through the active router. 
Creating two HSRP groups with an active router each is incorrect because it only allows load balancing between two of the routers and not three of them. 
Creating two HSRP groups with one active router for both groups, or three HSRP groups with one active router for all groups, is incorrect. Doing so does not enable load balancing on all three routers. Only the active router will be used for traffic forwarding. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Internetworking Case Studies > Using HSRP for Fault-Tolerant IP Routing > Configuring Multiple Hot Standby Groups > Load Sharing 
Catalyst 3750 Switch Software Configuration Guide, 12.2(40)SE > Configuring HSRP > Configuring HSRP > HSRP Configuration Guidelines 
Catalyst 3750 Switch Software Configuration Guide, 12.2(40)SE > Configuring HSRP > Configuring HSRP > Multiple HSRP




Question 8

Which virtual router states are defined in the GLBP protocol? (Choose two.)

  • A: Backup gateway
  • B: Primary gateway
  • C: Active virtual gateway
  • D: Active secondary gateway
  • E: Active virtual forwarder

Correct Answer: CE

Active virtual gateway and active virtual forwarder are the two states defined in the Gateway Load Balancing Protocol (GLBP). The active virtual gateway (AVG) is elected by the members of the GLBP group. The AVG creates the virtual MAC addresses that are assigned to each of the routers in the group. Each router is responsible for handling packets sent to its virtual MAC address. A GLBP router that forwards packets sent to its virtual MAC address is known as the active virtual forwarder (AVF). GLBP members communicate through hello messages sent every 3 seconds to the multicast address 224.0.0.102. 
The election of the AVG can be influenced by use of the priority command. By default, all routers configured for GLBP have a priority of 100. A higher value indicates a higher priority. The configured priority of a router can be seen in the show run command as shown below:
 
 

In the above scenario, all other members of the group were left to the default, which can be determined on those routers by the absence of any priority entry in the 
show run command. In that case, this router would become the AVG. To remove a priority configuration, execute the nostandby priority command. When this 
command is executed, the router will revert to the default of 100. When all routers are left to the default, the router with the highest configured IP address will 
become the active router. 
GLBP is a Cisco-designed protocol that provides for the dynamic utilization of redundant routers in a broadcast network. It differs from HSRP and VRRP in that it is not necessary to configure multiple groups to fully use redundant paths or routers. GLBP has a configurable load-balancing mechanism that will distribute the use of redundant gateways servicing a broadcast network, such as an Ethernet LAN. Each host will have its gateway set to the address of the AVG. When a host issues an ARP to resolve its gateway's MAC Address, the AVG will respond with the virtual MAC address of a selected AVF. The AVG will perform load balancing by varying which virtual MAC it selects to use in the response. The AVF will own that assigned virtual MAC as long as the gateway is active. If an AVF becomes unable to provide service as gateway, another AVF can assume ownership of the virtual MAC. 
Consider the partial output of the show run command for two routers participating in the GLBP group shown below:
 
 

In the above scenario, both routers have the same priority, so Router B will become AVG. Hosts will use a gateway address of 192.168.5.5 (the GLBP virtual address in line 4 of both outputs). When hosts send an ARP message for the MAC address of the gateway, Router B will reply with the MAC address of the next AVF. 
The AVG can be configured to use one of three load-balancing algorithms:
Round-Robin Load-Balancing: Using round-robin load- balancing the AVG in turn points to each AVF virtual MAC address in its ARP reply (default method).
Weighted Load-Balancing: Using weighted load- balancing, the AVG selects an AVF virtual MAC address to use in the ARP reply proportionally based on the advertised weight value configured in a GLBP gateway. 
Host Dependant Load-Balancing: Using host-dependant load- balancing, the AVG selects an AVF virtual MAC address to use in the ARP reply based on which one the host used previously. A host will use the same AVF as long as the GLBP group is unchanged. 
GLBP allows better use of network resources by using the standby router through the load-balancing mechanism. The standby router is an available gateway for the network. 
GLBP and HSRP are Cisco-developed solutions. VRRP is defined in RFC 2338. 
Backup gateway, primary gateway, and active secondary gateway are not terms used when discussing GLBP. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco > Cisco IOS IP Application Services Configuration Guide, Release 12.4 > Part 1: First Hop Redundancy Protocols > Configuring GLBP
Cisco > First Hop Redundancy Protocols Configuration Guide, Cisco IOS Release 12.4 > Configuring GLBP > GLBP Active Virtual Gateway




Question 9

You are in the process of verifying the operation of your core switches, which are using HSRP. One core switch was left with the default priority; the other was given a lower priority to make it the standby switch. The command show standby brief was executed on one of the switches. Output of the command is shown below:
 

 
What does this output mean? (Choose all that apply.) 

  • A: this switch is using the default priority 
  • B: this switch is the active HSRP switch
  • C: the HSRP devices are up and functioning correctly
  • D: the switch intended to be the active switch has failed and this switch has taken over
  • E: preemption is enabled for the group

Correct Answer: BDE

The output in the exhibit indicates that this switch is the active HSRP switch, the switch intended to be the active switch has failed, and that preemption is enabled for the group. 
This is the active switch because Active is the State listed for each interface that is a member of HSRP. 
The question states that the switch that was intended to be the standby switch was given a priority lower than the default. The default priority is 100, so this is not the switch intended to be the active switch. This information indicates that the switch intended to be the active switch has failed. 
Preemption is enabled, as indicated by the P following the priority value in line 2. Since preemption is enabled, the switch with the priority of 100 is still down. When that switch is corrected and joins the group again, it will take over as active. 
The HSRP group is still providing access for users, but not all devices are functioning properly. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco IOS Master Command List, Release 12.4T>show ip route profile through sshow mpls atm-ldp summary>Cisco IOS IP Application Services Command 
Reference>show standby through show udp>show standby




Question 10

You are troubleshooting a problem with two routers configured in a HSRP group. You intended to configure the routers so that Router A and Router B would each track their respective Fa0/1 interfaces and decrement their priorities for several VLAN groups if the tracked interface went down. However, you find that Router A is not taking over as the active device for the HSRP group on VLAN 101 when the Fa0/1 interface on Router B fails. 
Which command would NOT be useful for discovering the problem? 


  • A: show running-configuration
  • B: show vlans
  • C: show standby brief
  • D: show standby

Correct Answer: B

The show vlans command would NOT be useful for discovering the problem. When troubleshooting a problem with Hot Standby Router Protocol (HSRP), the show vlans command will yield no useful information. The output of the command is shown below, demonstrating that there is no HSRP information provided. 
 
 

All three of the remaining commands will be useful in discovering information. Each is shown below with an example of its application to troubleshooting. 
Example A:show running-configuration Router B is not taking over as the active device for VLAN 101's HSRP group when the Fa0/1 interface on Router A fails. Below is a partial output of show run for both routers with the output focused on the section concerning VLAN 101's configuration on each. 
 
 

The above output displays the source of the problem. Router A has a decrement value of 5 configured for Fa0/1, as shown on the last line of the output after the specification of Fastethernet 0/1. This means that when its Fa0/1 interface goes down, Router A will subtract 5 from its priority for the VLAN 101 group, lowering it to 175. This is still higher than the priority of Router B, which is 170. Therefore, the solution is to change the decrement value for Router A to at least 11. When the interface goes down, Router A's priority will be decremented to 169, allowing Router B to take the role as active for the HSRP group in VLAN 101. 
Example B:show standby brief
Router C is not taking over as the active device for VLAN 102's HSRP group when the Fa0/1 interface on Router D fails. Below is a partial output of show standby brief for both routers C and D, with the output focused on the section concerning VLAN 102's configuration on each. 
Router C 
Interface Grp Prio P State Active addr Standby addr Group addr 
Fa0/1 102 200 Active local 10.10.10.253 10.10.10.251 
Router D 
Interface Grp Prio P State Active addr Standby addr Group addr 
Fa0/1 102 200 P Active local 10.10.10.253 10.10.10.251 
The absence of a P in the P (preempt) column in the output for Router C shows that it is not set to preempt. If not configured to preempt, it will never take over for Router D, regardless of its priority with respect to Router D. 
Example C: show standby
Router F is supposed to be the active router for VLAN 103's HSRP group. Occasionally both routers are shut down for maintenance over the weekend. After the routers are rebooted, Router F is not taking over as the active device for VLAN 103's HSRP group. Below is a partial output of the show standby command for both routers, with the output focused on the section concerning VLAN 103's configuration on each 
 
 

The output shows that Router F is not assuming the active role because of the priority and decrement values configured on the routers. When both routers go down, Router E will decrement its priority (200) by 10, as shown in last two lines of its output, leaving the priority at 190. Router F will decrement its priority (190) by 50 as shown in last two lines of its output, leaving the priority at 140. Therefore, to ensure that Router F maintains its role as active even after the dual shutdowns, the priority of Router F should be increased to at least 241. When both routers decrement their priorities after shutdown, Router F will then have a priority of 191, which will be higher than the priority value of Router E. 
Objective:
Infrastructure Services 
Sub-Objective:
Configure and verify first-hop redundancy protocols 
References:
Cisco > Home > Support > Technology Support > IP > IP Application Services > Design > Design Technotes > Understanding and Troubleshooting HSRP Problems 
in Catalyst Switch Networks 
Cisco > Home > Support > Technology Support > IP > IP Application Services > Design > Design Technotes > How to Use the standby preempt and standby track 
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