First Hop Redundancy Protocols (HSRP and VRRP)

50 questions

All types50 Multiple choice25 Multiple select14 Ordering11

A network technician is configuring high availability on interface GigabitEthernet0/1 of a Cisco IOS router. The interface is currently assigned the physical IPv4 address $192.168.10.1/24$ . The technician enters the command `standby 1 ip 192.168.10.1` under interface configuration mode. Which outcome will occur as a result of executing this command?

Cisco IOS rejects the virtual IP assignment because HSRP requires the virtual IP address to be distinct from any interface physical IP address in the group.

Cisco IOS accepts the configuration, and the router automatically sets its priority to 255 to become the permanent IP address owner for HSRP group 1.

Cisco IOS accepts the configuration, but HSRP hello packets are suppressed to prevent ARP table corruption on local LAN hosts.

Cisco IOS accepts the configuration, but automatically disables preemption across all routers participating in HSRP group 1.

Show answer & explanation

Answer: Cisco IOS rejects the virtual IP assignment because HSRP requires the virtual IP address to be distinct from any interface physical IP address in the group.

Answer

Cisco IOS rejects the virtual IP assignment because HSRP requires the virtual IP address to be distinct from any interface physical IP address in the group.

In Cisco IOS HSRP implementations, the virtual IP address must be a unique IP address within the local subnet that is not configured as the physical IP address of any interface in the HSRP group. When an administrator attempts to assign an existing physical IP address as the HSRP virtual IP, Cisco IOS rejects the command with an error message.

Step-by-Step Solution

Analyze the HSRP virtual IP configuration rule

HSRP (Hot Standby Router Protocol) requires an unassigned IP address within the subnet to serve as the shared virtual gateway IP.

Assigning an interface's active physical IP address as the HSRP virtual IP causes IP address conflicts and ARP resolution issues.

Compare HSRP behavior with VRRP behavior

While VRRP permits a router to act as the IP address owner (using its physical IP as the virtual IP with priority 255), HSRP explicitly forbids this.

Cisco IOS enforces this restriction at command entry for HSRP and generates an error message.

Determine the CLI command outcome

Executing `standby 1 ip 192.168.10.1` on an interface already using

192.168.10.1

causes Cisco IOS to reject the command.

The system prevents invalid HSRP group configuration.

Key Concept

HSRP Virtual IP Address Assignment Restrictions vs VRRP IP Ownership

Question 2Question →

A network administrator is configuring Hot Standby Router Protocol (HSRP) on a Cisco router interface that has already been assigned the physical IPv4 address 192.168.10.1/24. The administrator attempts to execute the command `standby 1 ip 192.168.10.1` on this interface. What is the result of executing this command?

The router rejects the command because HSRP does not permit assigning a router's physical interface IP address as the virtual IP address.

The router accepts the command and automatically sets its HSRP priority to 255 to become the IP address owner.

The command is accepted, but HSRP preemption is permanently disabled to prevent an IP address conflict with standby routers.

The command succeeds and the router immediately transitions to the Standby state regardless of its configured priority value.

Show answer & explanation

Answer: The router rejects the command because HSRP does not permit assigning a router's physical interface IP address as the virtual IP address.

Answer

The router rejects the command because HSRP does not permit assigning a router's physical interface IP address as the virtual IP address.

In Hot Standby Router Protocol (HSRP), the virtual IP address must be an unused, unique IP address within the local IPv4 subnet. Unlike Virtual Router Redundancy Protocol (VRRP), which allows the virtual IP address to match a physical interface IP address (making that router the IP address owner with priority 255), HSRP explicitly forbids using any member router's physical interface IP address. Attempting to do so in Cisco IOS results in an error message rejecting the command.

Step-by-Step Solution

Identify the protocol being configured and the requested virtual IP address.

The protocol is HSRP (v1/v2) and the command `standby 1 ip 192.168.10.1` attempts to use the physical IP address of the local interface (192.168.10.1).

Determining protocol-specific rules for Virtual IP (VIP) assignment is required to evaluate command validity.

Recall HSRP IP address assignment constraints.

HSRP requires the virtual IP address to be an unused IP address within the subnet shared by the gateway routers.

HSRP does not support the concept of an IP address owner sharing a physical IP address with the virtual IP address.

Determine the Cisco IOS CLI output behavior.

Cisco IOS generates an error indicating that the virtual IP address cannot match the interface IP address and rejects the command.

Executing a standby IP command with the interface's own IP address fails validation.

Key Concept

HSRP Virtual IP Address Assignment Constraints

Question 3Question →

A network engineer is configuring Virtual Router Redundancy Protocol (VRRP) on a router interface that has been assigned the physical IPv4 address $10.1.1.1/24$ . The engineer enters the command `vrrp 1 ip 10.1.1.1`. Which statement correctly describes the operational result of configuring the physical interface IP address as the VRRP virtual IP address?

VRRP accepts the configuration, allowing the router to become the IP address owner with a priority automatically set to 255.

VRRP rejects the command because virtual IP addresses must be outside the physical IP subnet range.

VRRP requires the virtual IP address to be a unique, unassigned IP address in the subnet, identical to standard HSRP behavior.

VRRP accepts the configuration but forces the router into a backup role with a default priority of 100.

Show answer & explanation

Answer: VRRP accepts the configuration, allowing the router to become the IP address owner with a priority automatically set to 255.

Answer

VRRP accepts the configuration, allowing the router to become the IP address owner with a priority automatically set to 255.

In VRRP, an engineer can assign the physical interface IP address as the virtual IP address. When this is done, the router becomes the IP address owner and its priority is automatically assigned as 255, making it the active Master router for that VRRP group.

Step-by-Step Solution

Identify the protocol and command syntax specified in the scenario.

The scenario uses VRRP (`vrrp 1 ip 10.1.1.1`) where the virtual IP address matches the primary physical interface IP address (

10.1.1.1

Understanding protocol-specific rules regarding virtual IP address assignment is essential.

Evaluate VRRP operational rules for IP address ownership.

RFC 5798 / VRRP standards state that if a router's physical interface IP address is configured as the VRRP virtual IP address, that router becomes the IP address owner.

VRRP permits virtual IP reuse, unlike HSRP which enforces separate virtual IP addresses.

Determine the resulting priority value for the IP address owner.

The IP address owner in VRRP automatically receives the highest possible priority value of 255.

This guarantees that the owner router will always become the Master router when functional.

Key Concept

VRRP IP Address Ownership and Priority Assignment

Question 4Question →

A network engineer is configuring first-hop redundancy for VLAN 20 on two Cisco IOS routers, R1 and R2. Interface GigabitEthernet0/0 on R1 is assigned IPv4 address 10.20.0.2/24, and GigabitEthernet0/0 on R2 is assigned 10.20.0.3/24. The engineer attempts to configure HSRP group 20 on R1 using the command `standby 20 ip 10.20.0.2`. The Cisco IOS CLI rejects the command with an error message. However, when configuring VRRP using `vrrp 20 ip 10.20.0.2`, the command is accepted successfully. What fundamental operational difference between HSRP and VRRP causes this behavior?

VRRP permits the virtual IP address to match the physical IP address of a router interface, appointing that router as the IP address owner with a default priority of 255, whereas HSRP strictly prohibits assigning any router's physical IP address as the virtual IP.

HSRP requires the virtual IP address to be identical to the active router's physical interface IP address, whereas VRRP requires a separate IP address outside the interface subnet range.

HSRP requires preemption to be explicitly enabled before a virtual IP address can be specified under the interface configuration, whereas VRRP automatically enables preemption by default.

VRRP uses a dedicated multicast group address to resolve physical-to-virtual IP mapping conflicts, whereas HSRP relies on broadcast traffic that prevents physical IP reuse.

Show answer & explanation

Answer: VRRP permits the virtual IP address to match the physical IP address of a router interface, appointing that router as the IP address owner with a default priority of 255, whereas HSRP strictly prohibits assigning any router's physical IP address as the virtual IP.

Answer

In Cisco IOS, HSRP mandates that the virtual IP address must be a unique IP address on the subnet and cannot be identical to any physical IP address configured on a router's interface. In contrast, VRRP allows the virtual IP address to match the interface physical IP address; the router whose physical IP matches the VRRP group virtual IP assumes the role of Master with an unalterable priority of 255 (IP address owner).

Step-by-Step Solution

Analyze the HSRP virtual IP configuration restriction.

HSRP requires that the virtual IP address defined in `standby <group> ip <address>` must be a unique, unused IP address on the subnet, separate from all physical interface IP addresses of the participating routers.

Assigning an existing physical IP address as an HSRP virtual IP address causes an IP overlap/conflict on the interface and is rejected by the Cisco IOS CLI.

Analyze the VRRP virtual IP configuration capability.

VRRP allows the virtual IP address to be identical to the primary physical IP address of one of the VRRP routers. The router owning that physical IP becomes the IP Address Owner and automatically receives a VRRP priority of 255.

VRRP standard RFC 5798 explicitly defines the IP address owner role to allow interface IP address sharing.

Select the option that accurately contrasts this behavior between HSRP and VRRP.

The correct response highlights that VRRP allows IP address ownership with a priority of 255 while HSRP prohibits physical IP reuse as the virtual IP.

This directly explains why HSRP rejected the configuration while VRRP accepted it.

Key Concept

HSRP vs VRRP Virtual IP Address Assignment and IP Address Ownership

Question 5Question →

A network engineer is configuring HSRP version 2 on interface GigabitEthernet0/1 of a Cisco IOS router. The interface has been assigned an IPv4 address of $192.168.50.1/24$ . The engineer enters the command `standby 10 ip 192.168.50.1` under interface configuration mode. Which statement accurately describes the operational result of executing this command?

The router rejects the command with an error because HSRP does not permit the virtual IP address to match an interface physical IP address.

The router accepts the command and automatically sets its HSRP priority to 255 to become the permanent IP address owner for the group.

The command is accepted, and HSRP successfully transitions to the Active state using

192.168.50.1

as both physical and virtual addresses.

The command is accepted, but HSRP remains in the Listen state until a secondary standby IP address is configured on the interface.

Show answer & explanation

Answer: The router rejects the command with an error because HSRP does not permit the virtual IP address to match an interface physical IP address.

Answer

The router rejects the command with an error because HSRP does not permit the virtual IP address to match an interface physical IP address.

In HSRP (both version 1 and version 2), the virtual IP address must be an unused IP address within the local subnet and cannot match the physical IP address of any interface participating in the HSRP group. Attempting to assign the physical interface IP address as the HSRP virtual IP results in an immediate Cisco IOS CLI error.

Step-by-Step Solution

Analyze HSRP virtual IP address configuration requirements.

HSRP (v1 and v2) mandates that the virtual IP address must be a unique IP address within the local IP subnet, distinct from all physical interface IP addresses assigned to participating routers.

Preventing duplicate IP usage and ensuring proper ARP resolution and packet routing logic across participating routers.

Compare HSRP behavior with VRRP IP address ownership rules.

Unlike VRRP—which allows the virtual IP address to be identical to a router's physical interface IP address (making that router the IP address owner with priority 255)—HSRP explicitly rejects commands attempting to assign an existing physical interface IP address as the standby virtual IP.

Distinguishing protocol-specific rules between Cisco proprietary HSRP and industry-standard VRRP.

Determine the CLI command execution outcome.

When `standby 10 ip 192.168.50.1` is entered on an interface already using

192.168.50.1/24

, Cisco IOS returns an error message and rejects the configuration.

The CLI parser enforces the HSRP virtual IP constraint upon command execution.

Key Concept

HSRP Virtual IP Address Assignment vs. VRRP IP Address Ownership

Question 6Question →

A network administrator enables HSRP version 2 on a Cisco IOS router interface configured with the highest priority in the group. In what order does the router progress through the standard HSRP operational states from initial interface bring-up to becoming the primary gateway?

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Answer

The correct chronological sequence of HSRP states during router initialization is Initial State, Listen State, Speak State, Standby State, and Active State.

HSRP routers follow a strict finite state machine sequence during initialization: Initial (interface up/config ready) -> Listen (receiving Hello messages passively) -> Speak (sending Hello messages to participate in election) -> Standby (acting as immediate backup) -> Active (handling virtual MAC/IP traffic).

Step-by-Step Solution

Identify the initial state upon interface bring-up

The router starts in the Initial state where protocol operations have not yet actively begun.

HSRP configuration is loaded but no network messages have been processed or sent.

Determine passive monitoring phase

The router transitions to the Listen state.

In Listen state, the router receives Hello packets to discover active group routers without sending any.

Identify active election participation

The router transitions to the Speak state.

In Speak state, the router starts transmitting Hello packets to announce its presence and priority.

Determine intermediate role election

The router moves into the Standby state.

Before becoming Active, the router becomes the Standby router monitoring the virtual IP group.

Identify final forwarding state

The router enters the Active state.

Because it possesses the highest priority, it claims the Active role and begins processing virtual MAC frames.

Key Concept

HSRP Finite State Machine (Initial -> Listen -> Speak -> Standby -> Active)

Question 7Question →

An engineer is monitoring an HSRP group on VLAN 30 between two switches, DSW1 and DSW2. DSW1 is configured with an HSRP priority of $115$ , preemption enabled, and interface tracking on interface GigabitEthernet1/0/1 with a priority decrement of $20$ . DSW2 is configured with an HSRP priority of $105$ and preemption enabled. Under normal operating conditions, DSW1 is the Active router. If interface GigabitEthernet1/0/1 on DSW1 goes down, which switch becomes the Active router for HSRP group 30, and what is DSW1's updated priority?

DSW2 becomes the Active router, and DSW1's priority is updated to

95

DSW1 remains the Active router because preemption only triggers when a higher-priority router reboots.

DSW2 becomes the Active router, and DSW1's priority is updated to

85

DSW1 remains the Active router because DSW2's priority of

105

is below the default active threshold of

110

Show answer & explanation

Answer: DSW2 becomes the Active router, and DSW1's priority is updated to $95$ .

Answer

DSW2 becomes the Active router, and DSW1's priority is updated to

95

When the tracked interface GigabitEthernet1/0/1 on DSW1 fails, HSRP interface tracking automatically reduces DSW1's priority by the configured decrement of

20

, bringing its priority down from

115

95

. Because DSW2 has an active priority of

105

(which is higher than

95

) and has preemption enabled, DSW2 immediately takes over the Active router role for HSRP group 30.

Step-by-Step Solution

Calculate the updated HSRP priority for DSW1 after interface failure

DSW1's initial priority of

115

minus the configured decrement of

20

equals

95

Interface tracking reduces the HSRP priority by the specified decrement value when the tracked interface enters a down state.

Compare the updated HSRP priorities between DSW1 and DSW2

DSW2 priority (

105

) is greater than DSW1 updated priority (

95

The HSRP election process favors the router with the highest priority value.

Evaluate preemption state to determine the active router

DSW2 preempts DSW1 and becomes the Active router for HSRP group 30.

Preemption is enabled on DSW2, allowing it to assume the Active role as soon as its priority exceeds the current Active router's priority.

Key Concept

HSRP Interface Tracking and Preemption Mechanics

Estimated Time:1m 0s

Question 8Question →

A network administrator is evaluating First Hop Redundancy Protocols (FHRPs) for deployment across enterprise campus VLANs. The engineering team requires a precise comparison of HSRPv2 and VRRPv2 operational mechanics regarding multicast communication, virtual IP assignment, and role terminology. Which two statements accurately describe the differences and similarities between HSRPv2 and VRRPv2?

Select all that apply

HSRPv2 uses the multicast IPv4 address 224.0.0.102 for protocol messages, whereas VRRPv2 sends advertisements to the multicast IPv4 address 224.0.0.18.

VRRPv2 allows a router's physical interface IP address to be configured as the virtual IP address, whereas HSRPv2 rejects using an active physical interface IP address as the virtual IP address.

HSRPv2 formats virtual MAC addresses using the prefix 0000.5e00.01XX, whereas VRRPv2 formats virtual MAC addresses using the prefix 0000.0c9f.fXXX.

HSRPv2 designates the primary forwarding gateway as the Master router, whereas VRRPv2 designates the primary forwarding gateway as the Active router.

Show answer & explanation

Answer: HSRPv2 uses the multicast IPv4 address 224.0.0.102 for protocol messages, whereas VRRPv2 sends advertisements to the multicast IPv4 address 224.0.0.18.; VRRPv2 allows a router's physical interface IP address to be configured as the virtual IP address, whereas HSRPv2 rejects using an active physical interface IP address as the virtual IP address.

Answer

The correct statements are that HSRPv2 uses multicast IPv4 address 224.0.0.102 while VRRPv2 uses 224.0.0.18, and VRRPv2 permits configuring a physical interface IP address as the virtual IP address while HSRPv2 requires a distinct virtual IP address.

The correct choices accurately identify the fundamental protocol differences: HSRPv2 sends messages to multicast IP 224.0.0.102 while VRRPv2 uses 224.0.0.18, and VRRPv2 allows configuring the IP address owner (where physical IP equals virtual IP) whereas HSRPv2 strictly prohibits using a physical interface IP address as the virtual IP.

Step-by-Step Solution

Analyze multicast destination address mechanics for HSRPv2 and VRRPv2.

HSRPv1 uses 224.0.0.2, HSRPv2 uses 224.0.0.102, and VRRP (v2/v3) uses 224.0.0.18. The comparison regarding multicast addresses is correct.

FHRP routers send periodic keepalive packets to specific well-known multicast IPv4 destination addresses.

Evaluate Virtual IP address assignment rules for both protocols.

VRRP supports IP Address Owner functionality (matching physical IP to virtual IP with priority 255). HSRP does not support assigning an interface's physical IP address as the virtual IP address.

Cisco IOS enforces distinct virtual IP addresses for HSRP to prevent ARP conflicts and interface state ambiguity.

Verify virtual MAC address structure and role terminology for HSRPv2 and VRRPv2.

HSRPv2 virtual MAC prefix is 0000.0c9f.fXXX and active role is 'Active'. VRRPv2 virtual MAC prefix is 0000.5e00.01XX and active role is 'Master'.

Reversing these prefixes or role names represents common protocol confusion.

Key Concept

HSRPv2 vs VRRPv2 Feature Comparison

Estimated Time:1m 15s

Question 9Question →

A network engineer enables preemption on router R1 (configured with HSRP priority $120$ ) while router R2 (configured with HSRP priority $100$ ) is currently acting as the Active gateway for HSRP Group 1. In what chronological sequence do the protocol events occur as router R1 takes over the Active role?

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Answer

The correct sequence for HSRP active gateway preemption is: 1) Router R1 receives HSRP Hello packets from R2, 2) Router R1 compares priorities and triggers preemption, 3) Router R1 sends an HSRP Coup message, 4) Router R2 relinquishes the role and sends an HSRP Resign message, and 5) Router R1 becomes Active and broadcasts a Gratuitous ARP.

When a router configured with a higher HSRP priority and preemption comes online, it must first receive Hello packets from the current Active router to detect the priority difference. Once detected, it sends an HSRP Coup packet. The lower-priority router acknowledges this by issuing an HSRP Resign packet and moving to Standby. Finally, the new router enters the Active state and issues a Gratuitous ARP (GARP) to update Layer 2 switch forwarding tables.

Step-by-Step Solution

Identify active discovery

R1 processes Hello packets from current active router R2 containing priority

100

Before preempting, the candidate router must learn the current active router's operating parameters.

Evaluate preemption condition

R1 determines its priority (

120

) is higher than R2's (

100

) and preemption is configured.

Preemption allows a router with a higher priority to take over the Active state automatically.

Send takeover notification

R1 generates and transmits an HSRP Coup message.

The Coup message signals to the existing Active router that a superior router is taking over.

Relinquish active role

R2 processes the Coup message, transitions to Standby, and emits a Resign message.

The lower-priority active router steps down upon verifying the higher priority in the Coup message.

Finalize activation and update network paths

R1 enters Active state and sends a Gratuitous ARP (GARP).

The GARP forces adjacent switches to map the virtual MAC address to R1's port, preventing blackholing of user traffic.

Key Concept

HSRP Preemption Mechanics and Message Sequence

Question 10Question →

An enterprise LAN uses HSRP for gateway redundancy with interface tracking configured on Router R1 (currently Active). Router R2 is in the Standby state with preemption enabled. When R1's tracked WAN uplink interface fails, a sequence of failover actions takes place. Place the operational steps in the correct chronological order from first to last.

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Answer

The correct sequence begins with Router R1 detecting the tracked interface failure and decrementing its priority. Next, Router R1 advertises the reduced priority in an HSRP Hello message. Router R2 detects that its priority is now higher and transmits an HSRP Coup message to preempt the Active role. Finally, Router R2 assumes the Active state and broadcasts a Gratuitous ARP to update Layer 2 switch MAC tables.

The chronological order follows the exact functional steps of HSRP failover: local event detection and priority decrement happens first, advertising the lower priority via Hello messages occurs second, preemptive takeover via Coup message happens third, and Layer 2 switch table updates via Gratuitous ARP happen last.

Step-by-Step Solution

Identify the initial trigger event caused by interface tracking.

Router R1 detects the link failure on its monitored interface and immediately subtracts the configured track decrement value from its HSRP priority.

Interface tracking must first process the line protocol state change before modifying the protocol metric.

Communicate the updated priority to neighboring HSRP routers.

Router R1 encapsulates its updated (lower) priority into its standard HSRP Hello packet and multicasts it to 224.0.0.2 (or 224.0.0.102 for HSRPv2).

HSRP routers rely on periodic Hello packets to discover neighbor priorities and state changes.

Execute preemption election on the standby router.

Router R2 compares its priority against the received Hello priority. Finding its own priority higher, it transmits an HSRP Coup (or Speak/Active assertion) message.

The preemption feature allows a higher-priority router to claim the Active role from a lower-priority Active router.

Refresh the Layer 2 network path for client traffic.

Router R2 transitions to the Active state and broadcasts a Gratuitous ARP containing the virtual IP and virtual MAC address mapping.

Layer 2 switches along the LAN segment must update their CAM tables to forward frames destined for the gateway virtual MAC out the port connected to R2.

Key Concept

HSRP Interface Tracking and Preemption Failover Sequence

Question 11Question →

A network technician is configuring Hot Standby Router Protocol (HSRP) on Router R1 to provide default gateway redundancy for hosts in VLAN 20. Interface GigabitEthernet0/0/1 on R1 has been assigned the IPv4 address $172.16.20.1/24$ . The technician enters the following commands in interface configuration mode:

text
R1(config-if)# ip address 172.16.20.1 255.255.255.0
R1(config-if)# standby 20 ip 172.16.20.1

Which statement accurately describes the outcome of executing these configuration commands?

Cisco IOS rejects the virtual IP configuration because HSRP does not allow the virtual IP address to match a physical interface IP address on any participating router.

The router accepts the command and automatically enables HSRP preemption to ensure Router R1 becomes the permanent Active router for group 20.

Cisco IOS accepts the configuration and assigns Router R1 a default HSRP priority of 255 because it acts as the IP address owner for the standby group.

The router accepts the virtual IP address, but HSRP stays permanently in the Listen state until a secondary standby IP address is defined.

Show answer & explanation

Answer: Cisco IOS rejects the virtual IP configuration because HSRP does not allow the virtual IP address to match a physical interface IP address on any participating router.

Answer

Cisco IOS rejects the virtual IP configuration because HSRP does not allow the virtual IP address to match a physical interface IP address on any participating router.

In Cisco IOS Hot Standby Router Protocol (HSRP), the virtual IP address must be a unique, unassigned IPv4 address within the same IP subnet as the participating router interfaces. Cisco IOS will generate an error and reject any attempt to configure the virtual IP address to be identical to a physical interface IP address. Therefore, the statement noting that Cisco IOS rejects the configuration because HSRP does not allow matching physical IP addresses is correct.

Step-by-Step Solution

Analyze the proposed HSRP configuration command on Router R1.

The command attempts to assign

172.16.20.1

as the HSRP virtual IP address for group 20, which is already configured as the physical IP address of GigabitEthernet0/0/1.

Identifying potential IP address conflicts between physical interface addressing and FHRP virtual addressing.

Evaluate HSRP protocol rules regarding virtual IP address assignment.

HSRP requires the virtual IP address to be an unused IP address within the same logical subnet as the physical interface IP addresses.

HSRP routers share a virtual IP and virtual MAC address. If the virtual IP matches a physical IP, ARP and routing table resolution conflicts occur.

Contrast HSRP behavior with VRRP operational rules.

While VRRP permits a router to act as the IP address owner (where the virtual IP matches the physical interface IP and automatically receives priority 255), HSRP strictly prohibits this practice and rejects the command in Cisco IOS.

Distinguishing vendor-standard HSRP mechanics from IEEE standard VRRP mechanics.

Key Concept

HSRP Virtual IP Address Assignment Restrictions

Estimated Time:1m 15s

Question 12Question →

A network engineer has configured VRRPv2 between Router A (Master) and Router B (Backup) to provide default gateway redundancy for hosts on VLAN 10. Router A suddenly loses power and stops functioning. What is the correct sequence of operational events from the initial failure of Router A to the complete restoration of host traffic flow through Router B?

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Answer

The correct sequence of events is: 1) Router A stops transmitting VRRP Master Advertisement multicast frames. 2) The Master_Down_Interval timer on Router B expires after three missed intervals plus skew time. 3) Router B transitions its internal state from Backup to Master. 4) Router B broadcasts a Gratuitous ARP (GARP) frame mapping the VRRP virtual IP to its virtual MAC address. 5) Layer 2 switches update their MAC address tables to forward host traffic to Router B.

During a VRRP Master router failure, the active Master first stops transmitting VRRP advertisement multicast messages. The Backup router notices the missing messages and waits until its Master_Down_Interval timer (calculated as 3 x Advertisement Interval + Skew Time) expires. When the timer elapses, the Backup router transitions into the Master state. Immediately after becoming Master, it broadcasts a Gratuitous ARP (GARP) packet containing the virtual IP and virtual MAC address. Connected Layer 2 switches receive this GARP and update their MAC address tables so that outbound host traffic destined for the virtual default gateway is properly directed to the new Master router.

Step-by-Step Solution

Identify the initial link/device failure event.

Router A fails and immediately ceases broadcasting VRRP Master Advertisement messages to multicast address 224.0.0.18.

Power loss prevents Router A from generating periodic advertisement packets.

Determine the backup router timer monitoring phase.

Router B detects silence on VLAN 10 and waits for the Master_Down_Interval timer (3 * Advertisement_Interval + Skew_Time) to expire.

The timer ensures transient network delays do not trigger unneeded master election failovers.

Analyze the state transition on the backup router.

Once the Master_Down_Interval timer expires, Router B moves from Backup state to Master state.

VRRP finite state machine rules require a Backup router to assume Master status if advertisements stop.

Identify how the new Master announces its presence to Layer 2 infrastructure.

Router B broadcasts a Gratuitous ARP frame containing the virtual IP and virtual MAC address across the segment.

Notifies connected Layer 2 switches that frames sent to the virtual MAC address should be delivered to Router B's port.

Trace the Layer 2 forwarding table update and traffic resumption.

Switches update their MAC address tables and forward subsequent host gateway traffic to Router B.

Hosts continue sending packets to the unchanged virtual MAC, which switches now forward to Router B.

Key Concept

VRRP Master Failover and Convergence Sequence

Question 13Question →

A network administrator is designing default gateway redundancy for VLAN 50 using HSRPv1 and VRRPv2 across Cisco IOS switches. Which two statements correctly describe default operational behaviors or attributes of these protocols?

Select all that apply

VRRPv2 enables preemption by default, allowing a higher-priority backup router to immediately assume the Master role upon startup.

HSRPv1 uses the virtual MAC address structure

0000.0c07.acXX

, where

XX

represents the group number in hexadecimal format.

HSRPv1 permits assigning the active router's physical interface IP address as the group's virtual IP address.

VRRPv2 disables preemption by default, requiring explicit configuration to enable failover to a higher-priority router.

Show answer & explanation

Answer: VRRPv2 enables preemption by default, allowing a higher-priority backup router to immediately assume the Master role upon startup.; HSRPv1 uses the virtual MAC address structure $0000.0c07.acXX$ , where $XX$ represents the group number in hexadecimal format.

Answer

The two correct statements are that VRRPv2 enables preemption by default, allowing a higher-priority router to assume the Master role, and that HSRPv1 uses the virtual MAC address format 0000.0c07.acXX with the group number encoded in hexadecimal.

VRRPv2 enables preemption by default, enabling higher priority devices to immediately claim the Master role upon boot. Additionally, HSRPv1 uses the well-known virtual MAC prefix 0000.0c07.acXX, where XX represents the HSRP group number encoded in two hexadecimal digits.

Step-by-Step Solution

Evaluate preemption defaults for HSRPv1 and VRRPv2.

HSRPv1 has preemption disabled by default, whereas VRRPv2 has preemption enabled by default.

Understanding default preemption prevents unexpected active/master router elections after node reboots.

Analyze virtual MAC address structure for HSRPv1.

HSRPv1 uses 0000.0c07.acXX (where XX is the group number in hex), whereas VRRPv2 uses 0000.5e00.01XX.

Proper identification of FHRP MAC address formats is required for troubleshooting L2 MAC address tables.

Verify virtual IP address assignment constraints.

HSRP prohibits setting the virtual IP equal to a router's physical IP, while VRRP allows the master router to IP-address-own the virtual IP.

Distinguishes Virtual Router IP ownership capabilities between HSRP and VRRP.

Key Concept

HSRPv1 and VRRPv2 default operational parameters and virtual MAC structures

Question 14Question →

A network engineer is configuring VRRPv2 on a Cisco IOS router to provide default gateway redundancy for hosts on a subnet. The physical interface GigabitEthernet0/0 is configured with the IP address $172.16.10.1/24$ . The engineer then executes the interface command `vrrp 10 ip 172.16.10.1`. What is the operational effect of configuring the VRRP virtual IP address to match the physical interface IP address?

The router accepts the command and automatically sets its VRRP priority to 255, making it the IP address owner and Master router.

The router rejects the command with an error message because virtual IP addresses must be distinct from physical interface IP addresses.

The router accepts the command with the default priority of 100, but preemption must be manually enabled for it to become the Master router.

The command is accepted into the running configuration, but virtual MAC address generation fails due to a protocol prefix mismatch.

Show answer & explanation

Answer: The router accepts the command and automatically sets its VRRP priority to 255, making it the IP address owner and Master router.

Answer

The router accepts the command and automatically sets its VRRP priority to 255, making it the IP address owner and Master router.

In VRRPv2/v3, a router can use its own physical interface IP address as the group virtual IP address. When configured this way, the router becomes the IP address owner, and its VRRP priority is automatically forced to 255 (the highest possible priority), ensuring it acts as the Master router.

Step-by-Step Solution

Analyze protocol rules for VRRP IP address assignment.

VRRP permits the virtual IP address to be identical to the primary IP address assigned to an interface on one of the routers in the VRRP group.

This router is designated as the 'IP address owner'.

Determine the priority change associated with IP address ownership.

When a router is the IP address owner in VRRP, its priority automatically increases to 255.

Priority 255 is reserved exclusively for the IP address owner to guarantee it becomes the Master router during election.

Key Concept

VRRP IP Address Ownership and Priority Assignment

Question 15Question →

Place the operational events in chronological order from first to last during an HSRP interface tracking failover scenario, assuming preemption is enabled on the standby router.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological order for HSRP interface tracking failover is: (1) The monitored uplink interface on the Active router fails; (2) The Active router decrements its HSRP priority; (3) The Active router broadcasts an HSRP Hello packet with the reduced priority; (4) The Standby router detects its higher priority and sends a Coup message; (5) The newly promoted Active router broadcasts a Gratuitous ARP to update Layer 2 MAC address tables.

HSRP interface tracking failover follows a precise operational order: First, the tracked uplink interface fails on the Active router. Second, the Active router decrements its configured HSRP priority locally. Third, it advertises this reduced priority in an HSRP Hello packet. Fourth, the Standby router (with preemption enabled) receives the Hello, recognizes its priority advantage, and sends a Coup message to claim the Active role. Finally, the newly active router sends a Gratuitous ARP (GARP) to refresh Layer 2 switch forwarding tables for the virtual MAC address.

Step-by-Step Solution

Identify the initial trigger for tracking failover.

The monitored uplink interface fails, activating the tracking object on the Active router.

Interface tracking relies on physical or logical link state changes to initiate priority modification.

Determine the immediate local router response to the trigger.

The Active router reduces its operational priority by the configured decrement value.

HSRP tracking dynamically adjusts priority values to allow healthier backup routers to take over.

Determine how the priority change is communicated to the network.

The Active router advertises the lowered priority in its next HSRP Hello packet.

Peers must receive an updated Hello packet to learn about priority changes on neighboring devices.

Analyze the reaction of the Standby router.

The Standby router notices its priority is superior and sends a Coup message to assume the Active role.

Preemption permits a router with higher priority to claim the Active role immediately upon detecting lower priority Hellos.

Identify how Layer 2 network topology adjusts to the new Active router.

The newly active router broadcasts a Gratuitous ARP to force switches to update their MAC tables for the Virtual MAC.

Layer 2 switch ports must point to the new physical port holding the Virtual MAC to prevent traffic blackholing.

Key Concept

HSRP Interface Tracking and Preemption Failover

Question 16Question →

A network administrator configures HSRP group 10 on two Cisco IOS routers to provide high availability for the $192.168.10.0/24$ network.

Router R1 configuration:
text interface GigabitEthernet0/1 ip address 192.168.10.2 255.255.255.0 standby 10 ip 192.168.10.1 standby 10 priority 115 standby 10 preempt standby 10 track GigabitEthernet0/0 30

Router R2 configuration:
text interface GigabitEthernet0/1 ip address 192.168.10.3 255.255.255.0 standby 10 ip 192.168.10.1 standby 10 priority 100 standby 10 preempt

Initially, both routers and interfaces are fully operational, and R1 is the Active router. If interface GigabitEthernet0/0 on R1 experiences a link failure, which router will become the Active router for HSRP group 10, and what is R1's effective priority?

R2 becomes the Active router because R1's priority decrements to 85, which is lower than R2's priority of 100.

R1 remains the Active router because R1's priority decrements to 100, resulting in a tie where the current Active router retains its role.

R1 remains the Active router because R2 lacks interface tracking and cannot preempt an active router during an uplink failure.

R2 becomes the Active router because HSRP tracking immediately disables the standby group on R1 upon uplink failure.

Show answer & explanation

Answer: R2 becomes the Active router because R1's priority decrements to 85, which is lower than R2's priority of 100.

Answer

R2 becomes the Active router because R1's priority decrements to 85, which is lower than R2's priority of 100.

When the tracked uplink GigabitEthernet0/0 on R1 fails, HSRP interface tracking decrements R1's priority from 115 by 30, bringing its effective priority down to 85. Since R2 has preemption enabled and its priority of 100 is higher than R1's new priority of 85, R2 preempts R1 and becomes the Active router for HSRP group 10.

Step-by-Step Solution

Calculate the initial priorities and state of both HSRP routers.

R1 initial priority is 115 (Active). R2 priority is 100 (Standby). Both have preemption enabled.

Higher priority wins the Active role when preemption is enabled.

Evaluate the impact of GigabitEthernet0/0 failure on R1.

R1's tracked interface drops, reducing R1's priority by 30:

115 - 30 = 85

The command 'standby 10 track GigabitEthernet0/0 30' decrements the priority by 30 upon link down.

Determine the outcome of HSRP preemption.

R2's priority (100) is now higher than R1's effective priority (85). R2 sends coup messages and becomes Active.

R2 has 'standby 10 preempt' configured, allowing it to assume the Active role whenever its priority exceeds the current Active router's priority.

Key Concept

HSRP Priority Tracking and Preemption

Question 17Question →

A network administrator is evaluating default gateway redundancy protocol behavior on Cisco IOS switches for VLAN 10 ( $192.168.10.0/24$ ). Which two statements accurately contrast the default operational features of HSRPv1 and VRRPv2? (Choose two.)

Select all that apply

VRRPv2 enables preemption by default, whereas HSRPv1 disables preemption by default.

HSRPv1 uses virtual MAC addresses formatted as 0000.0c07.acXX, whereas VRRPv2 uses virtual MAC addresses formatted as 0000.5e00.01XX.

HSRPv1 allows assigning an active physical interface IP address as the virtual IP address, whereas VRRPv2 forbids matching the virtual IP to any physical interface IP.

VRRPv2 designates the active forwarding router as the Active router, whereas HSRPv1 designates it as the Master router.

Show answer & explanation

Answer: VRRPv2 enables preemption by default, whereas HSRPv1 disables preemption by default.; HSRPv1 uses virtual MAC addresses formatted as 0000.0c07.acXX, whereas VRRPv2 uses virtual MAC addresses formatted as 0000.5e00.01XX.

Answer

VRRPv2 enables preemption by default while HSRPv1 disables it by default, and HSRPv1 uses virtual MAC addresses in the format 0000.0c07.acXX while VRRPv2 uses 0000.5e00.01XX.

The correct statements accurately identify key default operational differences between Cisco proprietary HSRPv1 and open standard VRRPv2: VRRPv2 preemption is enabled by default while HSRPv1 preemption is disabled by default, and HSRPv1 uses the virtual MAC structure 0000.0c07.acXX compared to VRRPv2's 0000.5e00.01XX.

Step-by-Step Solution

Analyze preemption defaults for HSRPv1 and VRRPv2.

HSRPv1 requires explicit configuration of preemption to allow a higher priority router to claim the Active role. VRRPv2 has preemption enabled natively out of the box.

Understanding protocol default behaviors is essential for predicting failover and failback behavior during topology changes.

Analyze Virtual MAC address structures.

HSRPv1 uses vendor MAC prefix 0000.0c07.acXX, while VRRPv2 uses standard MAC prefix 0000.5e00.01XX.

Virtual MAC formatting allows Layer 2 switch forwarding tables to map the default gateway IP to the virtual router.

Evaluate role terminology and physical IP assignment constraints.

HSRP uses Active/Standby terminology and forbids virtual IP overlap with interface IPs. VRRP uses Master/Backup terminology and allows IP address ownership (priority 255).

This rules out distractors that swap role terminology or misstate virtual IP assignment capabilities.

Key Concept

First Hop Redundancy Protocols Default Features and Architectural Comparison

Estimated Time:1m 30s

Question 18Question →

A network administrator captures traffic on an Ethernet segment and identifies an ARP reply originating from a virtual default gateway with the MAC address $0000.5E00.0114$ . Which protocol and group number generated this virtual MAC address?

VRRP with group number 20

HSRP version 1 with group number 20

VRRP with group number 14

HSRP version 2 with group number 14

Show answer & explanation

Answer: VRRP with group number 20

Answer

VRRP with group number 20 is correct because VRRP for IPv4 utilizes the virtual MAC address format

0000.5E00.01XX

, where the last byte

14

in hexadecimal corresponds to decimal group number 20.

VRRP for IPv4 assigns virtual MAC addresses using the IANA OUI prefix

0000.5E00.01XX

, where

XX

is the group identifier in 2-digit hexadecimal. Converting hexadecimal

14

to decimal results in group 20.

Step-by-Step Solution

Identify the protocol vendor prefix from the virtual MAC address

The MAC address

0000.5E00.0114

uses the prefix

0000.5E00.01XX

, which is standard for VRRP IPv4 router redundancy.

VRRP specifies

00-00-5E-00-01-XX

as its standard virtual MAC address block, whereas HSRP v1 uses

00-00-0C-07-AC-XX

and HSRP v2 uses

00-00-0C-9F-F X-XX

Convert the final byte from hexadecimal to decimal to determine the group number

14_{16} = (1 \times 16^1) + (4 \times 16^0) = 16 + 4 = 20

The last byte of the VRRP virtual MAC address encodes the group number in hexadecimal notation.

Key Concept

VRRP and HSRP Virtual MAC Address Formats and Group Encoding

Question 19Question →

A network administrator has configured HSRPv2 between two routers, R1 and R2. Router R1 is currently the Active router with a configured priority of 120, preemption enabled, and tracking on its primary WAN interface configured to decrement priority by 30 upon link failure. Router R2 is currently the Standby router with a configured priority of 105 and preemption enabled. When R1's tracked WAN interface fails, a precise sequence of operational events occurs across the routers and local LAN switches to complete the failover. What is the correct chronological sequence of these events from first to last?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of events is: (1) R1's tracked WAN interface fails and internal priority decrements to 90, (2) R1 advertises priority 90 in an HSRP Hello packet, (3) R2 observes R1's lower priority and transmits an HSRP Coup message due to preemption, (4) R2 assumes Active status and transmits a Gratuitous ARP (GARP) frame to update switch CAM tables, and (5) R1 processes R2's higher-priority election and transitions to Standby status.

The failover process begins when R1's tracked interface fails, immediately decreasing its local priority from 120 to 90. R1 advertises this new priority of 90 in its subsequent HSRP Hello multicast packet. R2 reads R1's Hello packet, notices its own priority of 105 is higher than R1's 90, and generates an HSRP Coup message because preemption is enabled. R2 then transitions to Active status and broadcasts a Gratuitous ARP (GARP) frame so adjacent switches update their MAC address tables for the virtual MAC address. Finally, R1 receives R2's Active message and transitions to Standby status.

Step-by-Step Solution

Identify the initial interface failure and local priority recalculation.

R1's priority is decremented by 30 (120 - 30 = 90).

HSRP interface tracking continuously monitors the specified interface status and modifies the router priority locally upon state change.

Determine how priority changes are communicated across the subnet.

R1 sends an HSRP Hello packet advertising priority 90.

HSRP state updates and priority shifts must be transmitted via multicast Hello messages to peer routers.

Evaluate peer router reaction and preemption mechanism.

R2 compares priorities (105 vs 90) and sends a Coup message.

Because preemption is enabled on R2, R2 immediately attempts to claim the Active role when it sees an Active router with lower priority.

Analyze Layer 2 forwarding convergence.

R2 shifts to Active state and sends a Gratuitous ARP (GARP).

Layer 2 switches must learn that the virtual MAC address is now reachable via R2's switch port, which is accomplished via GARP frame broadcast.

Verify final state transition of the original Active router.

R1 transitions to Standby state.

R1 recognizes R2 as a valid Active router with higher priority (105 > 90) and completes demotion.

Key Concept

HSRP Interface Tracking, Preemption Coup Mechanics, and GARP Convergence

Question 20Question →

An enterprise network administrator is deploying First Hop Redundancy Protocols across two Cisco Catalyst routers, R1 (primary, physical IP $192.168.10.2/24$ ) and R2 (secondary, physical IP $192.168.10.3/24$ ), servicing subnet $192.168.10.0/24$ . The administrator is evaluating feature parities and operational behaviors between HSRPv2 and VRRPv3 for dual-stack IPv4/IPv6 resilience.

Which two statements accurately describe the operational differences and configuration mechanics between HSRPv2 and VRRPv3 in this environment? (Choose two.)

Select all that apply

VRRPv3 permits the virtual IP address to be identical to the physical interface IP address of the Master router (setting its priority automatically to 255), whereas HSRPv2 requires the virtual IP to be a unique IP address distinct from any physical interface IP assigned to routers in the standby group.

VRRPv3 preemption is enabled by default when configuring a VRRP group, whereas HSRPv2 requires explicit configuration of the preemption command for a higher-priority router to claim the Active role upon boot or recovery.

Configuring the HSRPv2 virtual IP address to match R1's physical IP address (

192.168.10.2

) is supported in Cisco IOS XE and automatically elevates R1's HSRP priority value to 255.

HSRPv2 uses multicast IPv4 address

224.0.0.18

and virtual MAC prefix `0000.5E00.01xx`, whereas VRRPv3 uses multicast IPv4 address

224.0.0.102

and virtual MAC prefix `0000.0C9F.Fxxx`.

Show answer & explanation

Answer: VRRPv3 permits the virtual IP address to be identical to the physical interface IP address of the Master router (setting its priority automatically to 255), whereas HSRPv2 requires the virtual IP to be a unique IP address distinct from any physical interface IP assigned to routers in the standby group.; VRRPv3 preemption is enabled by default when configuring a VRRP group, whereas HSRPv2 requires explicit configuration of the preemption command for a higher-priority router to claim the Active role upon boot or recovery.

Answer

The correct statements are: (1) VRRPv3 permits using the physical interface IP address as the virtual IP (which automatically forces priority to 255), while HSRPv2 mandates a unique virtual IP; and (2) VRRPv3 has preemption enabled by default, whereas HSRPv2 requires explicit configuration of the preemption command.

VRRPv3 supports IP address ownership where the virtual IP matches the physical interface IP of the master router, automatically setting priority to 255. Additionally, VRRP preemption is enabled by default. In contrast, HSRP requires a unique virtual IP address not assigned to any physical interface, and requires the explicit 'standby preemption' command to allow a higher-priority router to claim the Active role.

Step-by-Step Solution

Analyze Virtual IP Address Assignment Rules for HSRP and VRRP

VRRP allows the IP Address Owner to share its physical interface IP with the virtual IP address, giving it an unalterable priority of 255. HSRP requires that the virtual IP address be unassigned to any physical interface in the local group to prevent ARP and routing loop issues.

Understanding protocol specification RFCs (RFC 5798 for VRRPv3 vs Cisco proprietary HSRPv2 specs) is essential for proper IP addressing design.

Analyze Default Preemption Behavior

VRRP router processes preempt higher-priority backup nodes by default unless explicitly disabled using 'no vrrp preempt'. HSRP router processes do not preempt active nodes by default, requiring 'standby <group> preempt' to be configured on primary nodes.

Failing to configure preemption on an HSRP primary router will cause sub-optimal traffic flow after a router reboots.

Verify Multicast Addresses and Virtual MAC Allocations

HSRPv1 uses

224.0.0.2

(`0000.0C07.ACxx`), HSRPv2 uses

224.0.0.102

(`0000.0C9F.Fxxx`), and VRRPv2/v3 uses

224.0.0.18

(`0000.5E00.01xx`).

Distinguishing between multicast control planes and MAC structures avoids misidentifying frame header captures.

Key Concept

First Hop Redundancy Protocol (FHSRP) Operational Mechanics and Feature Comparison

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First Hop Redundancy Protocols (HSRP and VRRP)

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