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IP Connectivity

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Question 101Question →

Four OSPFv2 routers are connected to a shared multi-access Ethernet segment. Place the steps of the OSPF Designated Router (DR) election logic in the correct order of evaluation, from the initial eligibility filter to the final operational behavior.

Drag items to arrange them in the correct order

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Answer

The correct operational sequence is: Exclude routers with an OSPF priority of 0, select the candidate with the highest interface priority, break ties using the highest OSPF Router ID, and finally enforce non-preemption so an established DR remains active.
On multi-access broadcast networks, OSPF DR/BDR election begins by filtering out any router configured with priority 0. For remaining eligible routers, the router with the highest OSPF interface priority is preferred. If priorities are equal, the router with the highest Router ID breaks the tie. Once a DR is elected, the process is non-preemptive, meaning new routers joining the segment will not replace an active DR even if they have superior metrics.

Step-by-Step Solution

1
Filter out non-candidate routers.
Routers with `ip ospf priority 0` are excluded from election participation.
Setting priority to 0 explicitly forces a router to remain a DROTHER.
2
Evaluate interface priority values.
The candidate with the highest interface priority (range 1-255) is designated as winner.
Interface priority is the primary metric in OSPF DR/BDR elections.
3
Evaluate Router IDs if priorities match.
The router with the highest Router ID is selected.
Router ID acts as the definitive tie-breaker when OSPF priorities are tied.
4
Apply non-preemptive election rules.
The elected DR retains its role until the process or link resets.
OSPF prevents network instability and adjacencies reset by disallowing preemption.

Key Concept

OSPFv2 DR/BDR Election Logic and Precedence Rules
Question 102Question →

A network administrator configures the command `ip ospf network point-to-point` on interface GigabitEthernet0/1 of router R1, which connects directly to router R2 over an Ethernet segment in OSPFv2 Area 0. Which operational change occurs on this interface as a result of this configuration?

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Answer: OSPF suppresses Designated Router (DR) and Backup Designated Router (BDR) elections on the interface while maintaining the default 10-second Hello timer.

Answer

OSPF suppresses Designated Router (DR) and Backup Designated Router (BDR) elections on the interface while maintaining the default 10-second Hello timer.
On point-to-point OSPF networks, DR and BDR elections are completely suppressed because only two routers reside on the link. The default Hello and Dead timers for point-to-point network types on Ethernet media remain 10 seconds and 40 seconds, respectively.

Step-by-Step Solution

1
Analyze default OSPF behavior on Ethernet interfaces.
Ethernet interfaces default to the OSPF Broadcast network type, which requires DR/BDR election and uses Hello/Dead timers of 10s/40s.
Broadcast multiaccess networks elect a DR and BDR to reduce adjacency overhead on shared segments.
2
Evaluate the effect of the `ip ospf network point-to-point` command.
Changing the network type to point-to-point informs OSPF that only two routers exist on the link, rendering DR/BDR elections unnecessary.
Point-to-point OSPF network types do not elect a DR or BDR and establish FULL neighbor adjacencies directly between the two endpoints.
3
Verify timer changes associated with the Point-to-Point network type.
Point-to-Point interfaces retain the standard 10-second Hello and 40-second Dead timer defaults.
Only Non-Broadcast (NBMA) and Point-to-Multipoint network types change default timers to 30s/120s.

Key Concept

OSPFv2 Network Types and DR/BDR Election Behavior
Question 103Question →

A network administrator modifies the OSPFv2 router ID on an operational Cisco router by issuing the command `router-id 10.50.1.1` under `router ospf 1`. A system message informs the administrator that the change will not take effect until the OSPF process is reset. Which privileged EXEC mode command must be executed to immediately apply the new router ID?

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Answer: clear ip ospf process; clear ip ospf 1 process; clear ip ospf process 1

Answer

clear ip ospf process
When the `router-id` command is configured under an active OSPF process, Cisco IOS does not immediately change the operational Router ID in order to prevent unexpected disruption of established neighbor adjacencies. Executing the privileged EXEC command `clear ip ospf process` clears all OSPF structures and restarts the process, allowing the new router ID to take effect immediately.

Step-by-Step Solution

1
Analyze how OSPF handles changes to the Router ID on an active process.
Configuring the `router-id` command dynamically alters the intended configuration, but Cisco IOS holds the current active Router ID to prevent disrupting current neighbor adjacencies.
To apply the new Router ID without rebooting the entire device, the OSPF software process must be manually restarted.
2
Determine the exact command required in privileged EXEC mode to restart the OSPF process.
The command `clear ip ospf process` resets the OSPF database and neighbor relationships, forcing OSPF to re-initialize with the newly configured Router ID.
Running `clear ip ospf process` forces the OSPF process to tear down adjacencies and rebuild them using the new router ID.

Key Concept

OSPFv2 Router ID Modification and Process Reset
Question 104Question →

An engineer is configuring router R1 to reach the internal network 10.50.0.0/1610.50.0.0/16 using a backup path via next-hop IPv4 address 192.168.12.2192.168.12.2. The primary route to 10.50.0.0/1610.50.0.0/16 is currently dynamically learned via EIGRP with an administrative distance of 9090. Which command must be configured on R1 so that the static route functions as a floating static route and only enters the routing table if the primary route fails?

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Answer: ip route 10.50.0.0 255.255.0.0 192.168.12.2 95

Answer

ip route 10.50.0.0 255.255.0.0 192.168.12.2 95
The command 'ip route 10.50.0.0 255.255.0.0 192.168.12.2 95' correctly specifies the target network, subnet mask, next-hop IP address, and an administrative distance of 95. Because 95 is greater than the EIGRP administrative distance of 90, the router will keep this static route out of the routing table until the primary EIGRP route fails.

Step-by-Step Solution

1
Identify the primary route protocol and its administrative distance.
The primary route is learned via EIGRP, which has an Administrative Distance (AD) of 90.
Floating static routes rely on a higher AD value than the primary path to remain dormant in the routing table.
2
Determine the required Administrative Distance for the floating static route.
The static route must have an AD greater than 90 (such as 95).
Cisco routers prefer routes with lower AD values; setting the AD higher ensures it is only installed when the primary route disappears.
3
Verify Cisco IOS static route CLI command syntax.
The format is 'ip route <destination-prefix> <subnet-mask> <next-hop-ip> [administrative-distance]'.
Using dotted-decimal subnet masks and placing the AD at the end of the command line complies with Cisco IOS syntax.

Key Concept

Floating Static Route Administrative Distance Configuration
Estimated Time:1m 0s
Question 105Question →

A network administrator is troubleshooting an OSPFv2 neighbor relationship between two directly connected Cisco routers, R1 and R2. Execution of the `show ip ospf neighbor` command on R1 reveals that the adjacency state with R2 remains persistently stuck in the EXSTART state. Which configuration mismatch is the primary cause of this behavior?

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Answer: The maximum transmission unit (MTU) size differs between the interconnecting interfaces on R1 and R2.

Answer

The maximum transmission unit (MTU) size differs between the interconnecting interfaces on R1 and R2.
When OSPF routers establish adjacency, they exchange Database Description (DBD) packets during the EXSTART and EXCHANGE states. By default, Cisco routers include the interface MTU in DBD packets. If the MTU values on the connecting interfaces do not match, the router with the larger MTU sends DBD packets that the other router drops, or the router receiving a higher MTU value rejects the DBD packet. Consequently, the neighbor relationship gets stuck in the EXSTART (or EXCHANGE) state.

Step-by-Step Solution

1
Identify mandatory OSPF Hello packet matching parameters versus post-Hello exchange parameters.
Hello packet parameters (Area ID, Hello/Dead timers, Subnet Mask, Authentication) must match for routers to establish a neighbor relationship.
If Hello parameters mismatch, routers ignore Hello packets and never transition past DOWN state.
2
Analyze OSPF neighbor state progression to EXSTART.
Transitioning to EXSTART indicates that Hello packets were accepted and the routers passed through INIT and 2-WAY states.
In EXSTART, routers negotiate Master/Slave roles and initial Sequence Numbers using Database Description (DBD) packets.
3
Determine the cause of persistent EXSTART/EXCHANGE state hangs.
An interface MTU mismatch causes DBD packets exceeding the smaller MTU to be dropped or ignored, leaving the neighbor stuck in EXSTART.
Cisco IOS checks the Interface MTU field in incoming DBD packets by default; if there is a mismatch, the exchange cannot complete.

Key Concept

OSPFv2 Adjacency Requirements and MTU Verification in EXSTART State
Question 106Question →

Two Cisco routers are connected via a point-to-point Ethernet link and are configured to form an OSPFv2 neighbor relationship. Which two parameters transmitted within the OSPF Hello packet must match between both routers for an OSPFv2 neighbor adjacency to be successfully established? (Choose two.)

Select all that apply

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Answer: Area ID; Hello and Dead timer intervals

Answer

The correct parameters that must match in the OSPF Hello packet are the Area ID and the Hello and Dead timer intervals.
To form an OSPFv2 neighbor relationship, neighboring routers must share identical parameters in their Hello packets. Specifically, the Area ID and the configured Hello and Dead timer intervals must match. If either setting differs, the routers will refuse to transition past the INIT neighbor state.

Step-by-Step Solution

1
Analyze OSPF Hello packet contents required for neighbor formation.
Identify parameters exchange requirements during the Init and 2-Way neighbor state transitions.
OSPF routers inspect Hello packets received on an interface to verify compatible parameters.
2
Evaluate required matching parameters versus local settings.
Confirm that Area ID, Subnet Mask (on multiaccess links), Hello/Dead timers, Authentication, and Stub flags must match.
If any mandatory parameter mismatches, the Hello packet is discarded or the neighbor remains in the INIT state.
3
Evaluate non-matching parameters.
Determine that Process ID is local only, and Router ID must be unique rather than identical.
Process ID identifies local IOS memory processes, while duplicate Router IDs cause database conflict.

Key Concept

OSPFv2 Neighbor Adjacency Requirements
Question 107Question →

A network engineer must configure router R1 with a primary static route to reach destination subnet 192.168.20.0/24192.168.20.0/24 using next-hop IPv4 address 10.1.12.210.1.12.2. Additionally, a backup (floating) static route to the same destination subnet must be configured using next-hop IPv4 address 10.1.14.210.1.14.2 so that it only enters the routing table if the primary path becomes unavailable. Which TWO static route configuration commands must be applied on router R1 to satisfy these requirements? (Select TWO.)

Select all that apply

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Answer: ip route 192.168.20.0 255.255.255.0 10.1.12.2; ip route 192.168.20.0 255.255.255.0 10.1.14.2 10

Answer

The primary path requires the standard command 'ip route 192.168.20.0 255.255.255.0 10.1.12.2' (default AD of 1), while the backup path requires 'ip route 192.168.20.0 255.255.255.0 10.1.14.2 10' with a higher administrative distance.
To create a primary and backup static route relationship, the primary route is configured with the standard static syntax 'ip route 192.168.20.0 255.255.255.0 10.1.12.2', which defaults to an administrative distance of 1. The backup (floating) static route is configured with an administrative distance value strictly greater than the primary route's AD (such as 10) via 'ip route 192.168.20.0 255.255.255.0 10.1.14.2 10'. This ensures the backup route remains inactive until the primary route drops from the routing table.

Step-by-Step Solution

1
Identify the proper Cisco IOS static route syntax.
The command syntax is 'ip route <destination-prefix> <subnet-mask> <next-hop-ip> [administrative-distance]'.
This establishes reachability to the destination network via a specified next-hop address.
2
Determine the administrative distance (AD) for the primary static route.
Reaching 192.168.20.0/24 via 10.1.12.2 uses the default static AD of 1.
Static routes without an explicit distance parameter default to an AD of 1.
3
Determine the administrative distance required for a floating static backup route.
The backup path via 10.1.14.2 requires an AD greater than 1 (such as 10).
A higher AD keeps the route out of the routing table until the lower AD primary route fails.

Key Concept

IPv4 Floating Static Route Configuration and Administrative Distance
Question 108Question →

Router R3 currently populates its routing table with a primary route to the 172.16.40.0/24172.16.40.0/24 network via OSPF, which carries a default administrative distance of 110110. A network administrator wants to implement a backup path to 172.16.40.0/24172.16.40.0/24 using the next-hop IPv4 address 10.2.2.210.2.2.2. The backup route must remain inactive in the routing table unless the primary OSPF path becomes unavailable. Which command should be entered on router R3 to accomplish this objective?

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Answer: ip route 172.16.40.0 255.255.255.0 10.2.2.2 130

Answer

The command `ip route 172.16.40.0 255.255.255.0 10.2.2.2 130` correctly configures a floating static route with an administrative distance higher than OSPF (110).
A floating static route is an administrative backup route configured with a higher Administrative Distance (AD) than the primary routing protocol. Since OSPF has an AD of 110110, configuring the static route with an AD of 130130 ensures it is ignored during normal operation. If the OSPF route disappears from the routing table, the static route with AD 130130 takes over forwarding.

Step-by-Step Solution

1
Identify the destination network, subnet mask, and next-hop IP address.
Destination: 172.16.40.0, Mask: 255.255.255.0, Next-hop IP: 10.2.2.2.
Cisco IOS static route syntax requires `ip route <prefix> <mask> <next-hop|exit-interface> [distance]`.
2
Determine the administrative distance (AD) of the primary protocol and choose a higher AD for the floating static route.
Primary OSPF AD is 110; the backup route AD must be greater than 110 (e.g., 130).
Routes with lower AD values are preferred. A higher AD ensures the static route remains floating (inactive) until the primary OSPF route fails.
3
Assemble the complete Cisco IOS CLI command string.
`ip route 172.16.40.0 255.255.255.0 10.2.2.2 130`.
This matches all parameter requirements and syntax rules.

Key Concept

Floating Static Route Administrative Distance Configuration
Estimated Time:1m 15s
Question 109Question →

A network engineer inspects a Cisco router named Branch-R1 that was recently configured for OSPFv2 routing. The interface configuration and operational states on Branch-R1 are as follows:

- Loopback 0: 192.168.50.1/32 (Status: Administratively Down)
- Loopback 1: 10.10.10.1/32 (Status: Up/Up)
- GigabitEthernet 0/0: 172.16.200.1/24 (Status: Up/Up)
- GigabitEthernet 0/1: 10.200.1.1/30 (Status: Up/Up)

No manual OSPF router ID has been configured under the `router ospf 1` process. Which IP address will OSPFv2 select as the Router ID for Branch-R1 upon initialization?

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Answer: 10.10.10.1

Answer

10.10.10.1 is selected as the OSPF Router ID because it is the highest IP address among active operational loopback interfaces.
OSPF Router ID election follows a strict hierarchy: 1) Manually configured router ID (`router-id` command), 2) Highest IPv4 address on an active (Up/Up) loopback interface, 3) Highest IPv4 address on an active (Up/Up) non-loopback/physical interface. Because Loopback 0 is administratively down, Loopback 1 (10.10.10.1) is the only active loopback interface and is selected.

Step-by-Step Solution

1
Check for an explicitly configured OSPF router ID
No manual `router-id` command is configured under `router ospf 1`.
Explicit configuration takes precedence over automatic election logic.
2
Evaluate operational state of loopback interfaces
Loopback 0 is administratively down and ignored. Loopback 1 (10.10.10.1) is operational (Up/Up).
OSPF election logic only considers interfaces in an active Up/Up state.
3
Apply OSPF selection hierarchy
The active loopback address (10.10.10.1) is chosen over physical interface IP addresses.
Active loopbacks take precedence over physical interfaces regardless of IP numerical value.

Key Concept

OSPFv2 Router ID Selection Hierarchy
Question 110Question →

Match each OSPFv2 network type or interface configuration on a Cisco router to its corresponding DR/BDR election behavior and default Hello/Dead timer settings.

Click a left item, then click its matching right item

Items

Broadcast Multi-Access
Point-to-Point
Interface Priority 0
Non-Broadcast Multi-Access (NBMA)

Matches

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Answer

Broadcast Multi-Access matches with 'Elects DR/BDR; default Hello/Dead timers are 10s / 40s'; Point-to-Point matches with 'Suppresses DR/BDR election; default Hello/Dead timers are 10s / 40s'; Interface Priority 0 matches with 'Excludes interface from DR/BDR election; remains permanently in DROTHER state'; Non-Broadcast Multi-Access (NBMA) matches with 'Elects DR/BDR; default Hello/Dead timers are 30s / 120s'.
Each OSPFv2 network type defines specific election rules and default timer values. Broadcast multi-access networks elect a DR and BDR with 10s Hello and 40s Dead timers. Point-to-Point networks suppress DR/BDR elections while maintaining 10s/40s timers. Interface priority 0 explicitly prevents participation in DR/BDR elections, locking the interface into DROTHER state. NBMA networks elect a DR and BDR with extended 30s/120s timer intervals.

Step-by-Step Solution

1
Determine DR/BDR election requirement for multi-access vs. point-to-point topologies
Broadcast and NBMA networks require DR/BDR elections; Point-to-Point networks bypass DR/BDR elections entirely.
DR/BDR elections prevent the N(N−1)/2N(N-1)/2 full mesh adjacency scaling issue on shared multi-access media.
2
Verify default Hello and Dead timers for each network type
Broadcast and Point-to-Point default to 10s Hello / 40s Dead. NBMA defaults to 30s Hello / 120s Dead.
Non-broadcast topologies use longer timers to accommodate potential WAN delays and manual neighbor definitions.
3
Evaluate explicit priority configuration overrides
An OSPF interface priority set to 0 overrides all Router ID tie-breakers and forces the interface to remain a DROTHER.
Priority 0 is designed specifically to prevent low-capacity or hub-and-spoke spoke routers from becoming DR/BDR.

Key Concept

OSPFv2 Network Types and DR/BDR Selection Rules
Question 111Question →

A Cisco router receives an IPv4 packet destined for 192.168.10.45192.168.10.45. The router has a single static route configured as follows: `ip route 192.168.10.0 255.255.255.0 10.1.1.2`. Arrange the steps of the router's lookup and packet forwarding process in the correct sequential order from first to last.

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Answer

The correct order of steps for processing a recursive static route lookup is: (1) Receive the IPv4 packet on an ingress interface, (2) Match the destination IP to the static route prefix 192.168.10.0/24192.168.10.0/24, (3) Identify next-hop IP 10.1.1.210.1.1.2 and initiate a recursive lookup, (4) Resolve the next-hop IP to connected route 10.1.1.0/3010.1.1.0/30 on interface GigabitEthernet0/1, and (5) Encapsulate the packet into a Layer 2 frame and transmit out GigabitEthernet0/1.
When a static route is configured using a next-hop IP address rather than an explicit exit interface (e.g., `ip route 192.168.10.0 255.255.255.0 10.1.1.2`), Cisco IOS performs a recursive lookup process. The router first matches the packet's destination IPv4 address to the static route entry. Next, it extracts the next-hop IP address and performs a second routing table lookup to find which interface connects to that next-hop subnet. Once the exit interface is identified from a connected or secondary route, the router encapsulates the packet in a Layer 2 frame and sends it out the resolved interface.

Step-by-Step Solution

1
Receive IPv4 packet
Packet destination IP 192.168.10.45192.168.10.45 is extracted for table inspection.
Ingress processing triggers the forwarding decision engine.
2
Match static route prefix
Destination matches `192.168.10.0/24` with next-hop `10.1.1.2`.
Static route entry specifies the destination network reachable via a next-hop IP address.
3
Perform recursive route lookup
Secondary lookup query initiated for IP address 10.1.1.210.1.1.2.
Static routes configured with only a next-hop IP address require a recursive lookup to identify the outgoing physical interface.
4
Resolve outbound interface
Next-hop 10.1.1.210.1.1.2 resolves to connected interface GigabitEthernet0/1.
The routing table contains a directly connected prefix 10.1.1.0/3010.1.1.0/30 attached to GigabitEthernet0/1.
5
Encapsulate and forward frame
Packet is sent out GigabitEthernet0/1.
Final packet transmission requires determining the Layer 2 header rewrite details for the specific exit interface.

Key Concept

IPv4 Static Route Recursive Lookup Mechanism
Question 112Question →

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 192.168.50.1/24192.168.50.1/24. 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?

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

1
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.
2
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.
3
Determine the CLI command execution outcome.
When `standby 10 ip 192.168.50.1` is entered on an interface already using 192.168.50.1/24192.168.50.1/24, 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 113Question →

A network administrator initializes OSPFv2 process 1 on a Cisco router named Branch-GW. The router does not have an explicit `router-id` command configured under `router ospf 1`. The operational status and IPv4 addresses of the router interfaces are listed below:

- Loopback1: 10.10.10.10/32 (Up / Up)
- Loopback2: 10.200.1.1/32 (Up / Up)
- Loopback3: 172.16.50.1/32 (Up / Up)
- GigabitEthernet0/0: 192.168.100.1/24 (Up / Up)
- GigabitEthernet0/1: 192.168.200.1/24 (Up / Up)

What IPv4 address will OSPFv2 elect as the router ID for Branch-GW?

Show answer & explanation

Answer: 172.16.50.1

Answer

172.16.50.1
OSPFv2 elects the router ID using a strict three-tier precedence hierarchy: 1) Manually configured `router-id` command, 2) Highest IPv4 address among active (Up/Up) loopback interfaces, 3) Highest IPv4 address among active physical interfaces. Because no manual router ID is specified, OSPF evaluates the active loopback interfaces. Among Loopback1 (10.10.10.10), Loopback2 (10.200.1.1), and Loopback3 (172.16.50.1), Loopback3 has the highest IPv4 address (172.16.50.1). Active loopbacks take precedence over physical interfaces, so the higher physical interface addresses (192.168.100.1 and 192.168.200.1) are ignored.

Step-by-Step Solution

1
Check for an explicitly configured router ID under the OSPF process.
No `router-id` command is configured.
A manually configured router ID has the highest priority in OSPF election logic.
2
Identify active (Up/Up) loopback interfaces on the router.
Three active loopback interfaces exist: Loopback1 (10.10.10.10), Loopback2 (10.200.1.1), and Loopback3 (172.16.50.1).
Active loopback interfaces take precedence over all physical interfaces regardless of IP address values.
3
Determine the highest IPv4 address among the active loopback interfaces.
172.16.50.1 is numerically greater than 10.200.1.1 and 10.10.10.10.
When multiple active loopbacks are present, OSPF selects the highest numeric IPv4 address as the router ID.

Key Concept

OSPFv2 Router ID Election Priority Logic
Estimated Time:1m 0s
Question 114Question →

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?

Drag items to arrange them in the correct order

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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

1
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.
2
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.
3
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.
4
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.
5
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 115Question →

A network administrator needs to configure static routes on a Cisco IOS router for destination subnet 10.15.0.0/1610.15.0.0/16. The primary route should use next-hop IP address 192.168.1.2192.168.1.2 with default priority. Additionally, a floating static backup route must be configured via next-hop IP address 192.168.2.2192.168.2.2 to take over only if the primary path learned via OSPF (Administrative Distance 110) becomes unavailable. Which two CLI commands correctly configure this static routing behavior? (Select TWO options.)

Select all that apply

Show answer & explanation

Answer: ip route 10.15.0.0 255.255.0.0 192.168.1.2; ip route 10.15.0.0 255.255.0.0 192.168.2.2 120

Answer

The correct commands are 'ip route 10.15.0.0 255.255.0.0 192.168.1.2' for the primary static route and 'ip route 10.15.0.0 255.255.0.0 192.168.2.2 120' for the floating static route.
The standard primary static route is configured using subnet mask notation with an implicit administrative distance of 1. To create a floating static route that acts as a backup to OSPF (which has a default administrative distance of 110), the static route must explicitly specify an administrative distance greater than 110, such as 120.

Step-by-Step Solution

1
Determine the syntax for the primary IPv4 static route.
The command syntax is 'ip route <destination-prefix> <subnet-mask> <next-hop-ip>'. For 10.15.0.0/1610.15.0.0/16, this is 'ip route 10.15.0.0 255.255.0.0 192.168.1.2'.
Standard static routes use default administrative distance 1.
2
Determine the administrative distance needed for the floating static backup route.
The backup route must have an administrative distance greater than OSPF (AD = 110), such as 120.
Routes with lower administrative distance are preferred in the routing table. To act as a backup to an OSPF route, the static route AD must exceed 110.

Key Concept

IPv4 Floating Static Route Configuration and Administrative Distance
Estimated Time:1m 30s
Question 116Question →

An engineer is monitoring an HSRP group on VLAN 30 between two switches, DSW1 and DSW2. DSW1 is configured with an HSRP priority of 115115, preemption enabled, and interface tracking on interface GigabitEthernet1/0/1 with a priority decrement of 2020. DSW2 is configured with an HSRP priority of 105105 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?

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Answer: DSW2 becomes the Active router, and DSW1's priority is updated to 9595.

Answer

DSW2 becomes the Active router, and DSW1's priority is updated to 9595.
When the tracked interface GigabitEthernet1/0/1 on DSW1 fails, HSRP interface tracking automatically reduces DSW1's priority by the configured decrement of 2020, bringing its priority down from 115115 to 9595. Because DSW2 has an active priority of 105105 (which is higher than 9595) and has preemption enabled, DSW2 immediately takes over the Active router role for HSRP group 30.

Step-by-Step Solution

1
Calculate the updated HSRP priority for DSW1 after interface failure
DSW1's initial priority of 115115 minus the configured decrement of 2020 equals 9595.
Interface tracking reduces the HSRP priority by the specified decrement value when the tracked interface enters a down state.
2
Compare the updated HSRP priorities between DSW1 and DSW2
DSW2 priority (105105) is greater than DSW1 updated priority (9595).
The HSRP election process favors the router with the highest priority value.
3
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 117Question →

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

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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

1
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.
2
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.
3
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 118Question →

A network engineer enables preemption on router R1 (configured with HSRP priority 120120) while router R2 (configured with HSRP priority 100100) 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

1
Identify active discovery
R1 processes Hello packets from current active router R2 containing priority 100100.
Before preempting, the candidate router must learn the current active router's operating parameters.
2
Evaluate preemption condition
R1 determines its priority (120120) is higher than R2's (100100) and preemption is configured.
Preemption allows a router with a higher priority to take over the Active state automatically.
3
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.
4
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.
5
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 119Question →

A Cisco router configured with the static route `ip route 172.16.10.0 255.255.255.0 10.1.1.2` receives an IPv4 packet destined for 172.16.10.45172.16.10.45. Place the steps performed by the router to process and forward this packet in the correct sequential order from first to last.

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Answer

The correct sequence of router operation steps is: (1) Packet arrival at ingress interface, (2) Destination matching against static route prefix 172.16.10.0/24, (3) Extraction of next-hop IP 10.1.1.2, (4) Recursive routing table lookup for 10.1.1.2 to find egress interface, and (5) Layer 2 encapsulation and forwarding out the resolved exit interface.
When a router receives a packet destined for a subnet covered by a next-hop static route, it first matches the destination prefix, identifies the next-hop IP, and then executes a recursive lookup to find the directly connected egress interface before encapsulating and transmitting the frame.

Step-by-Step Solution

1
Inspect incoming packet destination
Destination IP 172.16.10.45172.16.10.45 is identified.
Routing processing begins as soon as a packet enters the router.
2
Lookup destination in IPv4 routing table
Matches `172.16.10.0/24` pointing to next-hop 10.1.1.210.1.1.2.
The router performs a longest prefix match against active routing table entries.
3
Extract next-hop address requirement
Next-hop IP 10.1.1.210.1.1.2 is identified.
The static route was configured using next-hop IP syntax rather than directly specifying an exit interface.
4
Execute recursive route resolution lookup
Egress interface (e.g., GigabitEthernet0/1) associated with subnet 10.1.1.0/2410.1.1.0/24 is resolved.
Cisco IOS requires a recursive lookup to resolve next-hop IP addresses to an active, directly connected egress interface.
5
Encapsulate and forward frame
Packet is framed and transmitted out the egress interface toward 10.1.1.210.1.1.2.
Layer 2 headers are constructed after exit interface and next-hop MAC resolution.

Key Concept

Recursive Lookup for Next-Hop IPv4 Static Routes
Question 120Question →

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

1
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.
2
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.
3
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.
4
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
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