HSRP Flashcards
What is HSRP?
Hot-standby routing protocol. A Cisco-proprietary FHRP.
What are the two router roles in HSRP?
Active and standby.
Do downstream devices know the real MAC/IP of the HSRP routers?
No, downstream devices only know the virtual MAC/IP shared by the routers.
What single command will add an interface to an HSRP group?
From interface config, “standby (group number) ip x.x.x.x”
What command can you use to troubleshoot your HSRP config?
From global config, “Show standby”
Can the virtual MAC/IP be shared by any physical MACs/IPs?
No, the virtual addresses must be unique.
HSRP is configured per ___.
VLAN.
The active router for a VLAN should also be the ___ for that VLAN.
Root bridge.
After initial configuration, what should not typically be occurring in the “show standby” output?
State changes, this usually indicates a problem.
What are the default timer values for HSRP?
Hello is three seconds, hold is ten seconds.
What is the hello timer?
Determines how often HSRP hello packets are sent.
What is the hold timer?
Determines how long the standby server will wait to hear a hello message before it takes over as the active server.
How is the virtual HSRP MAC generated?
By using the MAC address 00-00-0c-07-ac-xx, where “xx” equals the HSRP group number in hex.
Almost all HSRP configuration takes place in what config mode?
SVI configuration mode.
What value determines the active router?
Priority, higher is better.
What is the default HSRP priority?
100.
What command changes the router priority?
From SVI config, “standby __ priority __”
If two routers have equal priorities, which one wins the active router election?
The one with the higher IP.
Unless ___ is configured, priority changes will not affect the active router.
Preemption.
In HSRP, is preemption enabled by default?
No, it is not.
What is preemption delay?
Preemption delay is a feature that causes “new” active router to wait a certain amount of seconds after a priority change to take over as the active router.
How do you enable preemtption?
From SVI config, “standby __ preempt”
How do you enable preemption delay?
From SVI config, “standby __ preempt delay minimum _(number of seconds)_
List the HSRP states.
Disabled, initial, listen, speak, standby, active.
Describe the disabled state.
HSRP has not yet been configured on the router.
Describe the initial state.
HSRP has been configured, but is not running yet.
Describe the listen state.
Used for the election process. Occurs when the virtual IP is known, but the switch is waiting to hear hello packets from the other routers. Also occurs when a router has a lower priority than the standby router.
Describe the speak state.
The router is participating in the HSRP router election and is sending out hello packets.
Describe the standby state.
The router is next in line to become the active router.
Describe the active state.
Router is forwarding packets sent to the virtual IP.
Describe HSRP load balancing.
Create multiple HSRP groups with different IPs in the same subnet. Assign active router status to different devices, and manually set the default gateway for hosts.
Describe HSRP interface tracking.
Interface tracking allows an HSRP router to lower or raise its priority based on the status of an interface (down, up, etc.)
What is the standard interface tracking decrement value?
10.
For interface tracking to be effective, what must be enabled?
Preemption.
What can you track with interface tracking?
Interfaces, portchannels, loop-back addresses, etc.
How do you enable HSRP interface tracking?
From SVI config, “standby __ track _(what you’re tracking)_ _(decrement value)_
If a standby doesn’t takeover as active when it should, what should you check first?
If preemption is enabled.
What two timers does HSRP use? Describe them.
Hold timer and hello timer. Hold timer refers to how long a router will wait to hear from the active router before taking over. The hello timer refers to how often the router will send its own hello packets.
Do timers have to match between all routers in an HSRP group?
No, but they should.
What are the default HSRP timers?
Hold timer of 10 seconds, hello timer of 3 seconds. Typically these defaults work well.
How do you change the HSRP default timers?
From SVI config, “standby __ timers _(hello timer)_ _(hold timer)_
With HSRP authentication, what should you always use?
MD5 ecnryption.
What command will keep the HSRP keys from being viewed in the running config?
From global config, “service password-encryption”
What command enables HSRP authentication?
From SVI config, “standby __ authentication md5 key-string _(password)_”
HSRP authentication can also make use of what quality-of-life feature?
Key chains.
Which three of the following network features are methods used to achieve high availability? (Choose three)
A. Spanning Tree Protocol (STP)
B. Delay reduction
C. Hot Standby Routing Protocol (HSRP)
D. Dynamic routing protocols
E. Quality of Service (QoS)
F. Jitter management
Answer: A C D
Explanation
STP, HSRP and dynamic routing protocols provide backup paths to reach the destination and achieve high availability.
Note: Quality of Service (Qos) only prioritizes specific type of data over other types and provides no high availability.
Which command will ensure that R2 will be the primary router for traffic using the gateway address of 172.16.15.20?
HSRP_preempt.jpg
A. On R2 add the command standby 1 priority 80
B. On R1 add the command standby 1 priority 110
C. On R1 add the command standby 1 priority 80
D. On R2 remove the command standby 1 preempt
Answer: C
Explanation
By default the priority value of HSRP is 100 so in order to ensure that R2 will be the primary router for traffic using the gateway address of 172.16.15.20 we can set the priority of R2 higher than 100 or set the priority of R1 lower than 100 -> only C is correct.
Which command will need to be added to External_A to ensure that it will take over if serial 0/0 on External_B fails?
HSRP_track.jpg
A. standby 1 priority 130
B. standby 1 preempt
C. standby 1 track fastethernet 0/0
D. standby 1 track 10.10.10.1
Answer: B
Explanation
The “standby 1 preempt” command on External_A router will make External_A take over the active state if it learns that its priority is higher than that of External_B router. In this case, when S0/0 interface of External_B fails, its priority will be 105 – 10 = 95, which is smaller than the default priority value (100) on External_A.
Refer to the exhibit and the partial configuration on routers R1 and R2. Hot Standby Routing Protocol (HSRP) is configured on the network to provide network redundancy for the IP traffic. The network administrator noticed that R2 does not became active when the R1 serial0 interface goes down. What should be changed in the configuration to fix the problem?
HSRP_interface_down.jpg
A. The Serial0 interface on router R2 should be configured with a decrement value of 20.
B. The Serial0 interface on router R1 should be configured with a decrement value of 20.
C. R2 should be configured with a standby priority of 100.
D. R2 should be configured with a HSRP virtual address.
Answer: B
Explanation
When Serial0 of R1 goes down, the priority of R1 is still higher than that of R2 (115 – 10 = 105 > 100) so we should configured the decrement value of 20 on R1 with the command: standby 1 track Serial0 20.
Which two statements are true about the Hot Standby Router Protocol (HSRP)? (Choose two)
A. Load sharing with HSRP is achieved by creating multiple subinterfaces on the HSRP routers.
B. Routers configured for HSRP can belong to multiple groups and multiple VLANs.
C. Load sharing with HSRP is achieved by creating HSRP groups on the HSRP routers.
D. All routers configured for HSRP load balancing must be configured with the same priority.
E. Routers configured for HSRP must belong to only one group per HSRP interface.
Answer: B C
B is correct according to http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_19_ea1/configuration/guide/swhsrp.html
To load sharing with HSRP, we can divide traffic into two HSRP groups:
+ One group assigns the active state for one switch
+ The other group assigns the active state for the other switch
The example below shows how to load sharing with HSRP:
HSRP_load_sharing.jpg
In this topology, R1 is the active router for Group 1 and is the standby router for Group 2 while R2 is the active router for Group 2 and is the standby router for Group 1. The configurations of R1 and R2 are shown below:
R1:
interface fa0/1 //Group 1
ip address 192.168.1.2
standby 1 ip 192.168.1.1
standby 1 priority 150
standby 1 preempt
standby 1 track Serial 0
!
interface fa0/0 //Group 2
ip address 192.168.2.2
standby 2 ip 192.168.2.1
standby 2 priority 145
standby 2 preempt R2:
interface fa0/1 //Group 2
ip address 192.168.2.3
standby 2 ip 192.168.2.1
standby 2 priority 150
standby 2 preempt
standby 2 track Serial 0
!
interface fa0/0 //Group 1
ip address 192.168.1.3
standby 1 ip 192.168.1.1
standby 1 priority 145
standby 1 preempt
-> C is correct.
Note: An interface can belong to multiple HSRP groups, and the same HSRP group can be applied to different interfaces -> E is not correct.
Which statement best describes first-hop redundancy protocol status, given the command output in the exhibit?
HSRP_show_ip_arp.jpg
A. The first-hop redundancy protocol is not configured for this interface.
B. HSRP is configured for group 10.
C. HSRP is configured for group 11.
D. VRRP is configured for group 10.
E. VRRP is configured for group 11.
F. GLBP is configured with a single AVF.
Answer: C
Explanation
The MAC address of the last IP is 0000.0c07.ac0b indicates HSRP has been configured for group 11 (0b in hexa = 11 in decimal).
Refer to the exhibit. Assume that Switch_ A is active for the standby group and the standby device has only the default HSRP configuration. What conclusion is valid?
Switch_A(config-if)# ip address 10.10.10.1 255.255.255.0
Switch_A(config-if)# standby 1 priority 200
Switch_A(config-if)# standby 1 preempt
Switch_A(config-if)# standby 1 track interface fa 1/1
Switch_A(config-if)# standby 1 ip 10.10.10.10
A. If port Fa1/1 on Switch_ A goes down, the standby device will take over as active.
B. If the current standby device were to have the higher priority value, it would take over the role of active for the HSRP group.
C. If port Fa1/1 on Switch_ A goes down, the new priority value for the switch would be 190.
D. If Switch_ A had the highest priority number, it would not take over as active router.
Answer: C
Explanation
By default, the standby track interface decrement is 10 so if interface fa1/1 goes down, the new priority value is 200 – 10 = 190
Examine the router output above. Which two items are correct? (Choose two)
A. The local IP address of Router A is 10.1.0.6.
B. The local IP address of Router A is 10.1.0.20.
C. If Ethernet 0/2 goes down, the standby router will take over.
D. When Ethernet 0/3 of RouterA comes back up, the priority will become 105.
E. Router A will assume the active state if its priority is the highest.
Answer: D E
The current state of this router is “active” and the standby router is 10.1.0.6, which makes answer A incorrect)
The IP address of the local router is not mentioned so we can’t conclude answer B. Notice that the IP 10.1.0.20 is just the virtual IP address of this HSRP group.
+ “Tracking 2 objects, 0 up” -> both Ethernet0/2 and 0/3 are currently down so the priority of RouterA was reduced from 120 to 95 (120 – 15 – 10). Therefore when Ethernet0/3 is up again, the priority of RouterA will be 95 + 10 = 105 -> D is correct.
From the line “preempt enabled” we learn this router is configured with “preempt” command so it will take over the active state if its priority is the highest -> E is correct. But a funny thing in this question is even when two interfaces are down, the priority of RouterA is still higher than the standby router so it is still the active router (the priority of standby router is 75). This also makes answer C incorrect.
Refer to the exhibit. On the basis of the information provided in the exhibit, which two sets of procedures are best practices for Layer 2 and 3 failover alignment? (Choose two)
HSRP_STP.jpg
A. Configure the D-SW1 switch as the active HSRP router and the STP root for all VLANs. Configure the D-SW2 switch as the standby HSRP router and backup STP root for all VLANs.
B. Configure the D-SW1 switch as the standby HSRP router and the STP root for VLANs 11 and 110. Configure the D-SW2 switch as the standby HSRP router and the STP root for VLANs 12 and 120.
C. Configure the D-SW1 switch as the active HSRP router and the STP root for VLANs 11 and 110. Configure the D-SW2 switch as the active HSRP router and the STP root for VLANs 12 and 120.
D. Configure the D-SW2 switch as the active HSRP router and the STP root for all VLANs. Configure the D-SW1 switch as the standby HSRP router and backup STP root for all VLANs.
E. Configure the D-SW1 switch as the active HSRP router and the backup STP root for VLANs 11 and 110. Configure the D-SW2 switch as the active HSRP router and the backup STP root for VLANs 12 and 120.
F. Configure the D-SW1 switch as the standby HSRP router and the backup STP root for VLANs 12 and 120. Configure the D-SW2 switch as the standby HSRP router and the backup STP root for VLANs 11 and 110.
Answer: C F
Explanation
The “best practices for Layer 2 and 3 failover alignment” here means using load sharing of HSRP.
To load sharing with HSRP, we can divide traffic into two HSRP groups:
+ One group assigns the active state for one switch
+ The other group assigns the active state for the other switch
-> C and F are correct.
Also please read an example of HSRP load sharing in the explanation of Question 1 on this page.
HSRP has been configured between two Company devices. What kind of message does an HSRP configured router send out every 3 seconds?
A. Retire
B. Coup
C. Resign
D. Send
E. Hello
Answer: E
The following command was issued on a router that is being configured as the active HSRP router.
standby ip 10.2.1.1
Which statement is true about this command?
A. This command will not work because the HSRP group information is missing
B. The HSRP MAC address will be 0000 0c07 ac00
C. The HSRP MAC address will be 0000 0c07 ac01.
D. The HSRP MAC address will be 0000.070c ad01.
E. This command will not work because the active parameter is missing
Answer: B
Explanation
The full syntax of the command above is:
standby [group-number] ip [ip-address [secondary]]
Therefore in the command “standby ip 10.2.1.1″ we recognize it is using the default group-number, which is 0 -> The last two-digit hex value of HSRP MAC address should be “00″.
What can be determined about the HSRP relationship from the displayed debug output?
*Mar 1 00:12:16.871: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:16.871: SB11: Vl11 Active router is 172.16.11.112
*Mar 1 00:12:18.619: %LINK-3-UPDOWN: Interface Vlan11, changed state to up
*Mar 1 00:12:18.623: SB: Vl11 Interface up
*Mar 1 00:12:18.623: SB11: Vl11 Init: a/HSRP enabled
*Mar t 00:12:18.623: SB11: Vl11 Init-> Listen
*Mar 1 00:12:19.619: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1 1, changed state to up
*Mar 1 00:12:19.819: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:19.819: SB11: V111 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:22.815: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:22.815: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router
*Mar 1 00:12:25.683: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:25.683: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:28.623: SB11: Vl11 Listen: d/Standby timer expired (unknown)
*Mar 1 00:12:28.623: SB11: Vl11 Listen-> Speak
*Mar 1 00:12:28.623: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:28.659: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:28.659: SB11: Vl11 Speak h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:31.539: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00:12:31.539: SB11: Vl11 Speak h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 00:12:31.575: SB11: Vl11 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115
*Mar 1 00:12:34.491: SB11: Vl11 Hello in 172.16 11.112 Active pri 50 ip 172.16.11.115
A. Router 172.16.11.112 will be the active router because its HSRP priority is preferred over router 172.16.11.111
B. Router 172.16.11.111 will be the active router because its HSRP priority is preferred over router 172.16.11.112
C. The IP address 172.16.11.111 is the virtual HSRP router IP address.
D. The IP address 172.16.11.112 is the virtual HSRP router IP address.
E. The nonpreempt feature is enabled on the 172.16.11.112 router.
F. The preempt feature is not enabled on the 172.16.11.111 router.
Answer: F
Explanation
To understand the output you should learn these terms:
Field Description
SB Abbreviation for “standby”
Vl11 Interface on which a Hot Standby packet was sent or received.
Hello in Hello packet received from the specified IP address.
Hello out Hello packet sent from the specified IP address.
pri Priority advertised in the hello packet.
ip address Hot Standby group IP address advertised in the hello packet.
state Transition from one state to another.
(Reference: http://www.cisco.com/en/US/docs/ios/debug/command/reference/db_s1.html)
From the output we learn:
Line Debug output Description
1 Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115 Priority of 172.16.11.112 is 50 (its standby IP address is 172.16.11.115)
2 Active router is 172.16.11.112 The current active router is 172.16.11.112
3 Interface Vlan11, changed state to up Interface Vlan11 is turned on
6 Init-> Listen Our router changes from Init to Listen state
15 Listen-> Speak After the standby timer expired (line 14), our router changes from Listen to Speak state
16 Hello out 172.16.11.111 Speak pri 100 ip 172.16.11.115 Our router IP is 172.16.11.111, priority is 100 (its standby IP address is also 172.16.11.115)
18 Speak h/Hello rcvd from lower pri Active router The Hellos received from lower priority Active router but our router does not send Coup message to take over active state
In short, our router (172.16.11.111) changes from Init -> Listen -> Speak state. It received hellos from the active router 172.16.11.112 with lower priority but it does not send Coup message to take over active state -> It is not configured with the “preempt” command.
Refer to the exhibit. Based on the “debug standby” output in the exhibit, which HSRP statement is true?
*May 10 20:34:08.925: *SYS- 5-CONFIG_I: Configured from console by console
*May 10 20:34:10.213: LINK-3-UPDOWN: Interface Vlan11, changed state to up
*May 10 20:34:10.221: SB: Vl11 : Interface up
*May 10 20:34:10.221: SB11: Vl11 Init: a/HSRP enabled
*May 10 20:34:10.221: SB11: Vl11 Init -> Listen
*May 10 20:34:11.213: LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11 changed state to up
*May 10 20:34:20.221: SB11: Vl11 Listen: c/Active timer expired (unknown)
*May 10 20:34:20.221: SB11: Vl11 Listen -> Speak
*May 10 20:34:20.221: SB11: Vl11 Hello out 10.10.10, 111 Speak pri 100 ip 10.10. 10.115
*May 10 20:34:28.905; SB11: Vl11 Hello out 10.10.10.111 Speak pri 100 ip 10.10. 10.115
*May 10 20:34:30.221: SB11: Vl11 Speak: d/Standby timer expired (unknown)
*May 10 20:34:30.221: SB11: Vl11 Standby router is local
*May 10 20:34:30.221; SB11: Vl11 Speak -> Standby
*May 10 20:34:30.221; SB11: Vl11 Hello out 10.10.10.111 Standby pri 100 ip 10.10. 10.115
*May 10 20:34:30.221: SB11: Vl11 Standby: e/Active timer expired (unknown)
*May 10 20:34:30.221: SB11: Vl11 Active router is local
*May 10 20:34:30.221: SB11: Vl11 Standby router is unknown, was local
*May 10 20:34:30.221: SB11: Vl11 Standby -> Active
*May 10 20:34:30.221: %STANDBY-6- STATECHANGE: Vlan11 Group 11 state Standby -> Active
*May 10 20:34:30.221: SB11: Vl11 Hello out 10.10.10.111 Active pri 100 ip 10.10. 10.115
*May 10 20:34:33.085: SB11: Vl11 Hello out 10.10.10.111 Active pri 100 ip 10.10. 10.115
A. DSW111 is the active router because it is the only HSRP-enabled router on that segment.
B. DSW111 is the active router because the standby timer has been incorrectly configured.
C. DSW111 is the active router because it has a lower priority on that VLAN.
D. DSW111 is the active router because it has a lower IP address on that VLAN.
E. DSW111 is the active router and is advertising the virtual IP address 10.10.10.111 on VLAN 11.
Answer: A
Explanation
From the output we learn that DSW111 moves from Init -> Listen -> Speak -> Standby -> Active and all the messages are “Hello out” (no messages are “Hello in”). This means that DSW111 is the only router sending messages in this segment.
(If you don’t know about these terms please read the explanation of Question 6)
Refer to the exhibit. Based on the debug output shown in the exhibit, which three statements about HSRP are true? (Choose three.)
*Mar 1 00 16:43.095: %LINK-3-UPDOWN: Interface Vlan11, changed state to up
*Mar 1 00 16:43.099: SB: Vl11 Interface up
*Mar 1 00 16:43.099: SB11: Vl11 Init: a/HSRP enabled
*Mar 1 00 16:43.099: SB11: Vl11 Init -> Listen
*Mar 1 00 16:43.295: SB11: Vl11 Hello in 172.16.11.112 Active pri 50 ip 172.16.11.115
*Mar 1 00 16:43.295: SB11: Vl11 Active router is 172.16.11.112
*Mar 1 00 16:43.295: SB11: Vl11 Listen: h/Hello rcvd from lower pri Active router (50/172.16.11.112)
*Mar 1 o o 16:43.295: SB11: Vl11 Active router is local, was 172.16.11.112
*Mar 1 00 16:43.299: %STANDBY-6-STATECHANGE: Vlan11 Group 11 state Listen -> Active
*Mar 1 00 16:43.299: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00 16:43.303: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
*Mar 1 00 16:46.207: SB11: Vl11 Hello out 172.16.11.111 Active pri 100 ip 172.16.11.115
*Mar 1 00 16:49.095: SB11: Vl11 Hello in 172.16.11.112 Speak pri 50 ip 172.16.11.115
A. The router with IP address 172.16.11.111 has preempt configured.
B. The final active router is the router with IP address 172.16.11.111.
C. The router with IP address 172.16.11.112 has nonpreempt configured.
D. The priority of the router with IP address 172.16.11.112 is preferred over the router with IP address 172.16.11.111.
E. The router with IP address 172.16.11.112 is using default HSRP priority.
F. The IP address 172.16.11.116 is the virtual HSRP IP address.
Answer: A B F
Which protocol specified by RFC 2281 provides network redundancy for IP networks, ensuring that user traffic immediately and transparently recovers from first-hop failures in network edge devices or access circuits?
A. ICMP
B. IRDP
C. HSRP
D. STP
Answer: C
Explanation
HSRP is a Cisco-proprietary protocol developed to allow several routers or multilayer switches to appear as a single gateway IP address. This protocol is described in RFC 2281.
Which of the following HSRP router states does an active router enter when it is preempted by a higher priority router?
A. active
B. speak
C. learn
D. listen
E. init
F. standby
Answer: B
Explanation
First we should review all the HSRP States:
State Description
Initial This is the beginning state. It indicates HSRP is not running. It happens when the configuration changes or the interface is first turned on
Listen The router knows both IP and MAC address of the virtual router but it is not the active or standby router. For example, if there are 3 routers in HSRP group, the router which is not in active or standby state will remain in listen state.
Speak The router sends periodic HSRP hellos and participates in the election of the active or standby router.
Standby In this state, the router monitors hellos from the active router and it will take the active state when the current active router fails (no packets heard from active router)
Active The router forwards packets that are sent to the HSRP group. The router also sends periodic hello messages
Now let’s take an example of a router passing through these states. Suppose there are 2 routers A and B in the network; router A is turned on first. It enters the initial state. Then it moves to listen state in which it tries to hear if there are already active or standby routers for this group. After learning no one take the active or standby state, it determines to take part in the election by moving to speak state. Now it starts sending hello messages containing its priority. These messages are sent to the multicast address 224.0.0.2 (which can be heard by all members in that group). When it does not hear a hello message with a higher priority it assumes the role of active router and moves to active state. In this state, it continues sending out periodic hello messages.
Now router B is turned on. It also goes through initial and listen state. In listen state, it learns that router A has been already the active router and no other router is taking standby role so it enters speak state to compete for the standby router -> it promotes itself as standby router.
Now to our main question! We want router B to become active router so we set a higher priority number than the priority of A and ask router B to take over the role of active router (with the preempt command). Now router A will fall back to the speak state to compete for active or standby state -> it becomes standby router because its priority is now lower than that of router A. (Therefore answer B is correct).
Note: Suppose router A is in active state while router B is in standby state. If router B does not hear hello messages from router A within the holdtime, router B goes into speak state to announce its priority to all HSRP members and compete for the active state. But if at some time it receives a message from the active router that has a lower priority than its priority (because the administrator change the priority in either router), it can take over the active role by sending out a hello packet with parameters indicating it wants to take over the active router. This is called a coup hello message.
(Reference and good resource: http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094a91.shtml)
Which three statements are true of a default HSRP configuration? (Choose three)
A. The Standby hello time is 2 seconds.
B. Two HSRP groups are configured.
C. The Standby track interface priority decrement is 10.
D. The Standby hold time is 10 seconds
E. The Standby priority is 100.
F. The Standby delay is 3 seconds.
Answer: C D E
Explanation
The table below shows the default values of popular HSRP parameters:
Feature Default Setting
Standby group number 0
Standby MAC address System assigned as: 0000.0c07.acXX, where XX is the HSRP group number
Standby priority 100
Standby delay 0 (no delay)
Standby track interface priority 10
Standby hello time 3 seconds
Standby holdtime 10 seconds
Note:
* Standby delay: If router A is the HSRP active router and then loses a link, which causes it to become standby router, and then the link comes back, the delay command causes router A to wait before it becomes active again. For example, with the “standby preempt delay minimum 30” command, it waits for 30 seconds for the router to become active.
* Standby track: For example, consider this configuration:
standby priority 150
standby track serial 0
An HSRP priority of 150 is configured with the standby priority command and HSRP is configured to track the state of interface Serial0. Because no decrement value is specified in the standby track command, the HSRP priority is decremented by the default value of 10 when the tracked interface goes down.
(Reference: http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_12c_ea1/configuration/guide/swhsrp.html)
hostname Switch1
interface Vlan10
ip address 172.16.10.32 255.255.255.0
no ip redirects
standby 1 ip 172.16.10.110
standby 1 timers 1 5
standby 1 priority 130
hostname Switch2
interface Vlan10
ip address 172.16.10.33 255.255.255.0
no ip redirects
standby 1 ip 172.16.10.110
standby 1 timers 1 5
standby 1 priority 120
HSRP was implemented and configured on two switches while scheduled network maintenance was performed.
After the two switches have finished rebooting, you notice via show commands that Switch2 is the HSRP active router. Which two items are most likely the cause of Switch1 not becoming the active router? (Choose two)
A. booting delays
B. standby group number does not match VLAN number
C. IP addressing is incorrect
D. premption is disabled
E. incorrect standby timers
F. IP redirect is disabled
Answer: A D
Explanation
When two routers are turned on at the same time, the router completes booting process first will take the active role. Without the “preempt” configured, even a new router with a higher priority cannot take over the active role.In the configuration of Switch1 we don’t see the “preempt” command configured.
hostname Switch1
interface Vlan10
ip address 172.16.10.32 255.255.255.0
no ip redirects
standby 1 ip 172.16.10.110
standby 1 timers msec 200 msec 700
standby 1 preempt
hostname Switch2
interface Vlan10
ip address 172.16.10.33 255.255.255.0
no ip redirects
standby 1 ip 172.16.10.110
standby 1 timers msec 200 msec 750
standby 1 priority 110
standby 1 preempt
hostname Switch3
interface Vlan10
ip address 172.16.10.34 255.255.255.0
no ip redirects
standby 1 ip 172.16.10.110
standby 1 timers msec 200 msec 750
standby 1 priority 150
standby 1 preempt
Refer to the exhibit. Three switches are configured for HSRP. Switch1 remains in the HSRP listen state. What is the most likely cause of this status?
A. this is normal operation
B. standby group number does not match VLAN number
C. IP addressing is incorrect
D. incorrect priority commands
E. incorrect standby timers
Answer: A
Explanation
Only Switch 1 is not configured with the priority so it will have the default priority of 100, which is smaller than that of Switch2 (110) and Switch3 (150). Moreover, both Switch2 and Switch3 have the “preempt” command so surely Switch3 becomes active router while Switch2 becomes standby router -> Switch1 will be in listen state (Please read the explanation of question 2 to understand more about this state).
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1. All other interface were up. During this time, DSW1 remained the active device for Vlan 102′s HSRP group. You have determined that there is an issue with the decrement value in the track command in Vlan 102′s HSRP group. What need to be done to make the group function properly?
A. The DSW1′s decrement value should be configured with a value from 5 to 15
B. The DSW1′s decrement value should be configured with a value from 9 to 15
C. The DSW1′s decrement value should be configured with a value from 11 to 18
D. The DSW1′s decrement value should be configured with a value from 195 to less than 205
E. The DSW1′s decrement value should be configured with a value from 200 to less than 205
F. The DSW1′s decrement value should be greater than 190 and less 200
Answer: C
Explanation:
The question clearly stated that there was an issue with the decrement value in VLAN 102 so we should check VLAN 102 on both DSW1 and DSW2 switches first. Click on the PC Console1 and PC Console2 to access these switches then use the “show running-config” command on both switches
DSW1>enable
DSW1#show running-config
DSW2>enable
DSW2#show running-config
HSRP_show_run
As shown in the outputs, the DSW1′s priority is 200 and is higher than that of DSW2 so DSW1 becomes active switch for the group. Notice that the interface Gig1/0/1 on DSW1 is being tracked so when this interface goes down, HSRP automatically reduces the router’s priority by a configurable amount, in this case 5. Therefore the priority of DSW1 goes down from 200 to 195. But this value is still higher than that of DSW2 (190) so DSW1 remains the active switch for the group. To make DSW2 takes over this role, we have to configure DSW1′s decrement value with a value equal or greater than 11 so that its result is smaller than that of DSW2 (200 – 11 < 190). Therefore C is the correct answer.
During routine maintenance, G1/0/1 on DSW1 was shutdown. All other interface were up. DSW2 became the active HSRP device for Vlan101 as desired. However, after G1/0/1 on DSW1 was reactivated. DSW1 did not become the active HSRP device as desired. What need to be done to make the group for Vlan101 function properly?
A. Enable preempt on DSW1′s Vlan101 HSRP group
B. Disable preempt on DSW1′s Vlan101 HSRP group
C. Decrease DSW1′s priority value for Vlan101 HSRP group to a value that is less than priority value configured on DSW2′s HSRP group for Vlan101
D. Decrease the decrement in the track command for DSW1′s Vlan 101 HSRP group to a value less than the value in the track command for DSW2′s Vlan 101 HSRP group.
Answer: A
Explanation:
Continue to check VLAN 101 on both switches…
HSRP_show_run_2.jpg
We learned that DSW1 doesn’t have the “standby 1 preempt” command so it can’t take over the active role again even if its priority is the highest. So we need to enable this command on VLAN 101 of DSW1.
DSW2 has not become the active device for Vlan103′s HSRP group even though all interfaces are active. As related to Vlan103′s HSRP group. What can be done to make the group function properly?
A. On DSW1, disable preempt
B. On DSW1, decrease the priority value to a value less than 190 and greater than 150
C. On DSW2, increase the priority value to a value greater 241 and less than 249
D. On DSW2, increase the decrement value in the track command to a value greater than 10 and less than 50.
Answer: B or C
Explanation:
HSRP_vlan103
The reason DSW2 has not become the active switch for Vlan103 is because the priority value of DSW1 is higher than that of DSW2. In order to make DSW2 become the active switch, we need to increase DSW2′s priority (to higher than 200) or decrease DSW1′s priority (to lower than 190).
If G1/0/1 on DSW1 is shutdown, what will be the current priority value of the Vlan105′s group on DSW1?
A. 95
B. 100
C. 150
D. 200
Answer: A
Explanation:
Below is the output of VLAN 105:
HSRP_vlan105.jpg
If G1/0/1 on DSW1 is shutdown, its priority will decrease 55 so, its value will be 150 – 55 = 95
What is the configured priority value of the Vlan105′s group on DSW2 ?
A. 50
B. 100
C. 150
D. 200
Answer: B
Explanation:
Below is the output of VLAN 105 of DSW2:
HSRP_vlan105_DSW2.jpg
We don’t see the priority of DSW2 so it is using the default value (100).
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1 and DSW2. All other interface were up. During this time, DSW1 became the active device for Vlan104′s HSRP group. As related to Vlan104′s HSRP group, what can be done to make the group function properly?
A. On DSW1, disable preempt
B. On DSW2, decrease the priority value to a value less than 150
C. On DSW1, increase the decrement value in the track command to a value greater than 6
D. On DSW1, disable track command.
Answer: C
Explanation:
HSRP_vlan104
The question asks us how to keep the active role of DSW2. From the outputs, we learned that if both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW1 will be 150 – 1 = 149 and that of DSW2 will be 200 – 55 = 145 -> DSW1 will become the active switch.
The main point here is that we have to configure so in such a way that when both interfaces G1/0/1 of DSW1 and DSW2 are shutdown, the priority of DSW2 is still greater than that of DSW1. Therefore the priority value of DSW1 should be smaller than 145, or we have to configure the decrement value of DSW1 to a value greater than 6 ( 6 = 150 – 144) -> C is the correct answer.
Notice: To keep the active role of DSW2, we can disable “preempt” on DSW1 (answer A) so that it will not take over the active role when DSW1 is downed but it also means that VLAN 104 will not have active switch -> VLAN104 will fail.
You are a network technician, study the exhibit carefully. Assume that Host PC can ping the Corporate Headquarters and that HSRP is configured on DS1, which is then reloaded. Assume that DS2 is then configured and reloaded. On the basis of this information, what conclusion can be drawn?
HSRP_Reboot
DS1# show running-config
interface Vlan10
ip address 10.10.10.2 255.255.255.0
no ip redirects
standby 60 priority 105
standby 60 ip 10.10.10.1
standby 60 track GigabitEthernet 0/1
DS2# show running-config
interface Vlan10
ip address 10.10.10.3 255.255.255.0
no ip redirects
standby 60 priority 150
standby 60 ip 10.10.10.1
standby 60 track GigabitEthernet 0/1
A. DS1 will be the active router because it booted first.
B. DS1 will be the standby router because it has the lower IP address.
C. DS1 will be the active router because it has the lower priority configured.
D. DS2 will be the active router because it booted last.
Answer: A
Explanation:
The configuration does not have the “standby 60 preempt”command so the first booted router will take the active role with any priority.
What percentage of the outgoing traffic from the 172.16.10.0/24 subnet is being forwarded through R1?
R1-100%
If router R1 interface Etherne0/0 goes down and recovers, which of the statement regarding HSRP priority is true?
The interface will have its current priority incremented by 40 for HSRP group 1
What is the virtual mac-address of HSRP group 1?
4000.0000.0010
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1. All other interface were up. During this time, DSW1 remained the active device for Vlan 102’s HSRP group. You have determined that there is an issue with the decrement value in the track command in Vlan 102’s HSRP group. What need to be done to make the group function properly?
The DSW1’s decrement value should be configured with a value from 11 to 18
DSW2 has not become the active device for Vlan103’s HSRP group even though all interfaces are active. As related to Vlan103’s HSRP group. What can be done to make the group function properly?
On DSW2, increase the priority value to a value greater 200 and less than 250
If G1/0/1 on DSW1 is shutdown, what will be the current priority value of the Vlan105’s group on DSW1?
95
What is the configured priority value of the Vlan105’s group on DSW2 ?
100
During routine maintenance, it became necessary to shutdown G1/0/1 on DSW1 and DSW2. All other interface were up. During this time, DSW1 became the active device for Vlan104’s HSRP group. As related to Vlan104’s HSRP group, what can be done to make the group function properly?
On DSW1, increase the decrement value in the track command to a value greater than 6
