HSRP

Question 1

What is HSRP?

Answer 1

Hot-standby routing protocol. A Cisco-proprietary FHRP.

Question 2

What are the two router roles in HSRP?

Answer 2

Active and standby.

Question 3

Do downstream devices know the real MAC/IP of the HSRP routers?

Answer 3

No, downstream devices only know the virtual MAC/IP shared by the routers.

Question 4

What single command will add an interface to an HSRP group?

Answer 4

From interface config, “standby (group number) ip x.x.x.x”

Question 5

What command can you use to troubleshoot your HSRP config?

Answer 5

From global config, “Show standby”

Question 6

Can the virtual MAC/IP be shared by any physical MACs/IPs?

Answer 6

No, the virtual addresses must be unique.

Question 7

HSRP is configured per ___.

Answer 7

VLAN.

Question 8

The active router for a VLAN should also be the ___ for that VLAN.

Answer 8

Root bridge.

Question 9

After initial configuration, what should not typically be occurring in the “show standby” output?

Answer 9

State changes, this usually indicates a problem.

Question 10

What are the default timer values for HSRP?

Answer 10

Hello is three seconds, hold is ten seconds.

Question 11

What is the hello timer?

Answer 11

Determines how often HSRP hello packets are sent.

Question 12

What is the hold timer?

Answer 12

Determines how long the standby server will wait to hear a hello message before it takes over as the active server.

Question 13

How is the virtual HSRP MAC generated?

Answer 13

By using the MAC address 00-00-0c-07-ac-xx, where “xx” equals the HSRP group number in hex.

Question 14

Almost all HSRP configuration takes place in what config mode?

Answer 14

SVI configuration mode.

Question 15

What value determines the active router?

Answer 15

Priority, higher is better.

Question 16

What is the default HSRP priority?

Answer 16

100.

Question 17

What command changes the router priority?

Answer 17

From SVI config, “standby __ priority __”

Question 18

If two routers have equal priorities, which one wins the active router election?

Answer 18

The one with the higher IP.

Question 19

Unless ___ is configured, priority changes will not affect the active router.

Answer 19

Preemption.

Question 20

In HSRP, is preemption enabled by default?

Answer 20

No, it is not.

Question 21

What is preemption delay?

Answer 21

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.

Question 22

How do you enable preemtption?

Answer 22

From SVI config, “standby __ preempt”

Question 23

How do you enable preemption delay?

Answer 23

From SVI config, “standby __ preempt delay minimum (number of seconds)

Question 24

List the HSRP states.

Answer 24

Disabled, initial, listen, speak, standby, active.

Question 25

Describe the disabled state.

Answer 25

HSRP has not yet been configured on the router.

Question 26

Describe the initial state.

Answer 26

HSRP has been configured, but is not running yet.

Question 27

Describe the listen state.

Answer 27

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.

Question 28

Describe the speak state.

Answer 28

The router is participating in the HSRP router election and is sending out hello packets.

Question 29

Describe the standby state.

Answer 29

The router is next in line to become the active router.

Question 30

Describe the active state.

Answer 30

Router is forwarding packets sent to the virtual IP.

Question 31

Describe HSRP load balancing.

Answer 31

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.

Question 32

Describe HSRP interface tracking.

Answer 32

Interface tracking allows an HSRP router to lower or raise its priority based on the status of an interface (down, up, etc.)

Question 33

What is the standard interface tracking decrement value?

Answer 33

10.

Question 34

For interface tracking to be effective, what must be enabled?

Answer 34

Preemption.

Question 35

What can you track with interface tracking?

Answer 35

Interfaces, portchannels, loop-back addresses, etc.

Question 36

How do you enable HSRP interface tracking?

Answer 36

From SVI config, “standby __ track (what you’re tracking) (decrement value)

Question 37

If a standby doesn’t takeover as active when it should, what should you check first?

Answer 37

If preemption is enabled.

Question 38

What two timers does HSRP use? Describe them.

Answer 38

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.

Question 39

Do timers have to match between all routers in an HSRP group?

Answer 39

No, but they should.

Question 40

What are the default HSRP timers?

Answer 40

Hold timer of 10 seconds, hello timer of 3 seconds. Typically these defaults work well.

Question 41

How do you change the HSRP default timers?

Answer 41

From SVI config, “standby __ timers (hello timer) (hold timer)

Question 42

With HSRP authentication, what should you always use?

Answer 42

MD5 ecnryption.

Question 43

What command will keep the HSRP keys from being viewed in the running config?

Answer 43

From global config, “service password-encryption”

Question 44

What command enables HSRP authentication?

Answer 44

From SVI config, “standby __ authentication md5 key-string (password)”

Question 45

HSRP authentication can also make use of what quality-of-life feature?

Answer 45

Key chains.