Examkin

IP Connectivity

493 soru

Tüm türler493Çoktan seçmeli250Çoklu seçim113Eşleştirme25Sıralama60Boşluk doldurma22Kısa cevap23
Soru 401Soru →

Match each OSPFv2 network type or interface configuration on the left to its corresponding election behavior and default timer characteristics on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Broadcast Multiaccess interface
Point-to-Point interface
Interface configured with ip ospf priority 0
Non-Broadcast (NBMA) interface

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Broadcast Multiaccess matches electing DR/BDR with 10s/40s timers; Point-to-Point matches suppressing DR/BDR election with 10s/40s timers; Interface priority 0 matches disqualifying from DR/BDR election; Non-Broadcast matches electing DR/BDR with 30s/120s timers.
Broadcast multiaccess interfaces use 10s/40s timers and elect a DR/BDR. Point-to-Point interfaces use 10s/40s timers but suppress DR/BDR elections. Configuring priority 0 explicitly disqualifies an interface from election eligibility. Non-Broadcast interfaces elect a DR/BDR but use 30s/120s timers by default.

Adım Adım Çözüm

1
Determine DR/BDR election requirements for each network type.
Broadcast Multiaccess and Non-Broadcast networks require DR/BDR elections to manage multiaccess adjacencies, while Point-to-Point interfaces bypass DR/BDR elections completely.
Direct peer-to-peer topologies do not suffer from the N(N−1)/2N(N-1)/2 adjacency scaling problem of multiaccess media.
2
Evaluate default Hello and Dead timers for OSPF network types.
Broadcast and Point-to-Point network types use 10-second Hello and 40-second Dead timers. Non-Broadcast (NBMA) networks use 30-second Hello and 120-second Dead timers.
NBMA interfaces default to longer timers to account for WAN link characteristics.
3
Analyze the role of interface priority zero in DR/BDR selection.
An interface assigned a priority value of 0 is ineligible for election to DR or BDR status.
A priority value of 0 acts as an explicit override to prevent a router interface from becoming DR or BDR regardless of Router ID.

Anahtar Kavram

OSPFv2 Network Types, DR/BDR Selection Rules, and Default Timers
Soru 402Soru →

A network engineer is configuring first-hop redundancy on router R1's GigabitEthernet0/1 interface, which has been assigned the physical IPv4 address 192.168.20.1/24192.168.20.1/24. The engineer initially attempts to configure HSRP Group 20 using the command `standby 20 ip 192.168.20.1`, but then evaluates migrating the design to VRRPv2 using the command `vrrp 20 ip 192.168.20.1`. Assuming default protocol parameters are used, which operational distinction correctly describes how HSRP and VRRP handle this configuration attempt and default preemption behavior?

Cevabı ve açıklamayı göster

Cevap: HSRP rejects configuring the virtual IP address to match a physical interface IP address, whereas VRRP permits it, automatically assigning a priority of 255 to the IP address owner with mandatory preemption enabled.

Cevap

HSRP rejects configuring the virtual IP address to match a physical interface IP address, whereas VRRP permits it, automatically assigning a priority of 255 to the IP address owner with mandatory preemption enabled.
The correct answer accurately contrasts the Virtual IP assignment constraints and preemption defaults between Cisco HSRP and standard VRRP. HSRP mandates that the virtual IP address must be an unassigned, unique IP within the local subnet and will throw a configuration error if matched to a physical interface address. Furthermore, HSRP preemption is disabled by default. In contrast, VRRP allows the virtual IP address to be identical to a physical interface IP address on the router (making it the IP address owner with priority 255), and VRRP preemption is enabled by default.

Adım Adım Çözüm

1
Evaluate HSRP Virtual IP assignment rules
HSRP requires the Virtual IP address to be a unique IP address within the subnet that is NOT assigned to any physical interface on participating routers.
Cisco IOS HSRP prevents IP address duplication on physical interfaces to prevent ARP and routing loop anomalies.
2
Evaluate VRRP Virtual IP assignment rules (IP Address Owner)
VRRP permits the virtual IP address to match the primary physical IPv4 address of an interface.
When a router's interface physical IP matches the VRRP virtual IP, that router acts as the VRRP IP Address Owner and is automatically assigned the maximum priority of 255.
3
Analyze default preemption behavior in HSRP versus VRRP
HSRP preemption is disabled by default, whereas VRRP preemption is enabled by default.
VRRP RFC standards mandate that preemption is enabled out-of-the-box, ensuring a higher priority router always assumes the Master role, especially when priority is 255.

Anahtar Kavram

First Hop Redundancy Protocol (FHRP) Virtual IP Assignment and Preemption Defaults
Tahmini Süre:2m 0s
Soru 403Soru →

A network administrator is configuring a backup floating static route on router R1 to reach the internal subnet 10.20.0.0/1610.20.0.0/16. The primary path to this destination is currently learned dynamically via OSPF, which has a default Administrative Distance of 110110. The backup route should traverse next-hop IPv4 address 192.168.12.2192.168.12.2 and must enter the routing table only when the primary OSPF path becomes unavailable. Which Cisco IOS command correctly achieves this objective?

Cevabı ve açıklamayı göster

Cevap: ip route 10.20.0.0 255.255.0.0 192.168.12.2 120

Cevap

The correct command is 'ip route 10.20.0.0 255.255.0.0 192.168.12.2 120'.
A floating static route is configured by specifying an administrative distance higher than that of the primary routing protocol. Since OSPF has an Administrative Distance of 110, setting an AD of 120 ensures the static route remains untracked in the routing table during normal operation and only activates if the primary OSPF route drops out.

Adım Adım Çözüm

1
Determine the destination prefix and subnet mask for 10.20.0.0/16.
Destination prefix is 10.20.0.0 and the 16-bit subnet mask in dotted-decimal format is 255.255.0.0.
Cisco IOS static route syntax uses subnet masks rather than wildcard masks.
2
Identify the next-hop IP address.
Next-hop IP address is 192.168.12.2.
The scenario explicitly designates 192.168.12.2 as the exit path for backup traffic.
3
Select an Administrative Distance (AD) greater than the primary route's AD.
OSPF default AD is 110; therefore, the floating static route requires an AD greater than 110 (such as 120).
Routers prefer lower Administrative Distance values. Assigning a value higher than 110 ensures the static route remains inactive in the routing table until OSPF fails.

Anahtar Kavram

Floating Static Routes and Administrative Distance
Soru 404Soru →

Four Cisco routers (R1, R2, R3, and R4) are connected to a shared Ethernet broadcast segment (10.1.1.0/24). OSPFv2 process 1 is enabled simultaneously on all router interfaces attached to this segment. The relevant interface and router parameters are configured as follows:

- R1: Interface OSPF Priority = 100, Router ID = 192.168.1.1
- R2: Interface OSPF Priority = 200, Router ID = 10.2.2.2
- R3: Interface OSPF Priority = 200, Router ID = 10.3.3.3
- R4: Interface OSPF Priority = 0, Router ID = 10.254.254.254

Assuming all routers initialize at the same moment without any existing DR or BDR active on the link, which router will be elected as the Backup Designated Router (BDR)?

Cevabı ve açıklamayı göster

Cevap: R2

Cevap

R2 will be elected as the Backup Designated Router (BDR).
In OSPF multiaccess networks, DR and BDR elections evaluate interface priority first. Routers with priority 0 (R4) are excluded. Between R2 and R3 (both priority 200), R3 wins the DR role due to its higher Router ID (10.3.3.3 > 10.2.2.2). R2 has the highest remaining priority among eligible non-DR routers, making it the BDR.

Adım Adım Çözüm

1
Filter out ineligible routers based on OSPF interface priority.
R4 has an interface priority of 0 and is excluded from both DR and BDR elections.
A priority value of 0 explicitly prevents a router from becoming a DR or BDR.
2
Compare the interface priority values of the remaining eligible routers (R1, R2, R3).
R2 and R3 tie for the highest priority (200), while R1 has a lower priority (100).
OSPF elects DR and BDR based primarily on the highest interface priority.
3
Break the tie between R2 and R3 to elect the Designated Router (DR).
R3's Router ID (10.3.3.3) is higher than R2's Router ID (10.2.2.2), so R3 becomes DR.
When priority values are identical, the router with the highest Router ID wins the election.
4
Select the Backup Designated Router (BDR) from the remaining eligible routers.
R2 becomes the BDR because it has the highest remaining priority (200).
After DR selection, the router with the highest remaining priority (or highest Router ID in case of another tie) is selected as BDR.

Anahtar Kavram

OSPFv2 DR/BDR Election Rules and Priority 0 Ineligibility
Soru 405Soru →

A Cisco router initializes an OSPFv2 routing process without an explicitly configured OSPF router-id. The interface configuration and operational states are as follows:

• Loopback0: 172.16.1.10/24 (up/up)
• Loopback1: 172.16.2.5/24 (up/up)
• GigabitEthernet0/0: 10.1.1.1/24 (up/up)
• GigabitEthernet0/1: 192.168.100.1/24 (up/up)

What IP address will be selected as the OSPFv2 router ID?

Cevabı ve açıklamayı göster

Cevap: 172.16.2.5

Cevap

172.16.2.5
OSPFv2 determines the router ID using a strict three-tier priority order: 1) Explicitly configured router-id command under the OSPF process, 2) Highest IPv4 address among operational (up/up) loopback interfaces, 3) Highest IPv4 address among operational physical (non-loopback) interfaces. Because no manual router ID is specified, OSPF evaluates the loopback interfaces. Between Loopback0 (172.16.1.10) and Loopback1 (172.16.2.5), 172.16.2.5 is numerically higher and is selected as the router ID, overriding the physical interface address 192.168.100.1.

Adım Adım Çözüm

1
Check for a manually configured OSPF router ID under the OSPF process configuration.
No manual router ID is configured.
Explicit configuration always takes top priority in OSPF router ID selection.
2
Evaluate operational (up/up) loopback interfaces for the highest IPv4 address.
Loopback0 (172.16.1.10) and Loopback1 (172.16.2.5) are active. 172.16.2.5 is numerically greater than 172.16.1.10.
If no manual router ID exists, OSPF selects the highest IPv4 address among active loopback interfaces.
3
Determine the final OSPFv2 router ID without considering physical interfaces.
172.16.2.5 is chosen as the router ID.
Active physical interface IP addresses (such as 192.168.100.1) are only evaluated if zero active loopback interfaces exist.

Anahtar Kavram

OSPFv2 Router ID Election Precedence
Tahmini Süre:1m 0s
Soru 406Soru →

A network engineer is configuring a backup static route on a Cisco router for the destination network 10.100.4.0/2410.100.4.0/24. The primary path to this network is currently learned dynamically via internal EIGRP, which uses a default Administrative Distance of 9090. The engineer needs the static route to remain inactive in the routing table unless the EIGRP path fails. Which command correctly configures this floating static route?

Cevabı ve açıklamayı göster

Cevap: ip route 10.100.4.0 255.255.255.0 192.168.12.2 130

Cevap

The command specifying an administrative distance of 130 correctly configures the floating static route.
A floating static route requires an Administrative Distance (AD) value higher than that of the primary route protocol. Because internal EIGRP uses a default AD of 90, specifying an AD of 130 ensures the static route remains out of the IP routing table until the primary EIGRP route fails.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing protocol.
Internal EIGRP has a default AD of 90.
Floating static routes rely on AD precedence to remain dormant while the primary path is operational.
2
Determine the required Administrative Distance for the floating static route.
The static route must be assigned an AD value strictly greater than 90 (e.g., 130).
Cisco IOS prefers routes with lower AD values. Assigning an AD higher than 90 ensures the static route is installed into the routing table only if the EIGRP route is withdrawn.
3
Evaluate the syntax options for the correct trailing AD value.
The command 'ip route 10.100.4.0 255.255.255.0 192.168.12.2 130' correctly appends the custom AD 130.
It successfully creates a floating static backup route.

Anahtar Kavram

Floating Static Routes and Administrative Distance
Soru 407Soru →

An network engineer is configuring HSRP group 15 on a Cisco router interface that has been assigned the primary IPv4 address 172.16.20.2/24172.16.20.2/24. Which requirement must be met when defining the HSRP virtual IPv4 address for this interface?

Cevabı ve açıklamayı göster

Cevap: The virtual IPv4 address must belong to the 172.16.20.0/24172.16.20.0/24 subnet and cannot match the physical IPv4 address of any router in the group.

Cevap

The HSRP virtual IPv4 address must be in the same IPv4 subnet as the interface's physical IP address (172.16.20.0/24172.16.20.0/24), but it cannot be identical to the physical IPv4 address configured on any router participating in the HSRP group.
In HSRP (v1 and v2), the virtual IP address configured via the command `standby <group> ip <ip-address>` must reside within the same IP subnet as the router interface's physical IP address so local LAN clients can reach it as their default gateway. However, Cisco IOS explicitly blocks assigning a virtual IP address that matches any physical IP assigned to a router interface in the group.

Adım Adım Çözüm

1
Identify the physical IP subnet of the interface.
The interface has IP address 172.16.20.2/24172.16.20.2/24, placing it in the 172.16.20.0/24172.16.20.0/24 subnet.
Default gateway traffic from LAN clients must be reachable within their local IP broadcast domain.
2
Apply the HSRP virtual IP assignment rule.
Select an unassigned IP address within 172.16.20.0/24172.16.20.0/24 (e.g., 172.16.20.1172.16.20.1).
Cisco HSRP requires virtual IP addresses to belong to the local subnet and strictly forbids reusing any physical interface IP address of HSRP routers.

Anahtar Kavram

HSRP Virtual IP Address Assignment Requirements
Soru 408Soru →

A network administrator is configuring a backup floating static route on router R3 to reach the remote destination network 192.168.50.0/24. The primary path to this network is dynamically learned via EIGRP with a default administrative distance of 90. The secondary path should route traffic through the next-hop IPv4 address 10.1.1.2.

Which TWO statements regarding this floating static route configuration are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The command `ip route 192.168.50.0 255.255.255.0 10.1.1.2 100` correctly configures the backup route.; The floating static route will be installed into the active IPv4 routing table only when the primary EIGRP route is removed.

Cevap

The correct choices are using the command `ip route 192.168.50.0 255.255.255.0 10.1.1.2 100` and recognizing that the route is installed into the routing table only when the primary EIGRP route is removed.
To create a floating static route that backs up an EIGRP path (AD 90), the static route must be configured with an administrative distance greater than 90. The command specifying an AD of 100 correctly accomplishes this. As a result, the router holds the static route in reserve and only installs it into the active IPv4 routing table if the primary EIGRP route is withdrawn.

Adım Adım Çözüm

1
Identify the primary route's Administrative Distance (AD).
The primary path is learned via internal EIGRP, which has a default administrative distance of 90.
Floating static routes depend on AD ranking to remain inactive until the primary routing source drops.
2
Determine the required AD value for the floating static route.
The AD configured for the static route must be strictly greater than 90 (e.g., 100).
Cisco routers select routes with lower AD values for insertion into the active IPv4 routing table.
3
Evaluate the command syntax and routing behavior.
`ip route 192.168.50.0 255.255.255.0 10.1.1.2 100` correctly assigns an AD of 100, ensuring the route stays dormant while EIGRP is active.
If the static route AD is set lower than 90 (such as 80), it preempts EIGRP and improperly acts as the primary path.

Anahtar Kavram

Floating Static Route Administrative Distance Selection
Soru 409Soru →

Company router R1 currently reaches the remote subnetwork 192.168.50.0/24192.168.50.0/24 via internal EIGRP, which has a default Administrative Distance of 90. A network administrator wants to configure a backup floating static route to 192.168.50.0/24192.168.50.0/24 through the next-hop IP address 172.16.1.2. The floating route must remain inactive in the routing table until the primary EIGRP path becomes unavailable. Which Cisco IOS command correctly configures this floating static route?

Cevabı ve açıklamayı göster

Cevap: ip route 192.168.50.0 255.255.255.0 172.16.1.2 95

Cevap

The command 'ip route 192.168.50.0 255.255.255.0 172.16.1.2 95' correctly configures the floating static route.
A floating static route functions as a backup route by configuring an Administrative Distance (AD) higher than that of the primary routing source. Internal EIGRP has a default AD of 90. Configuring the static route with an AD of 95 ensures that Cisco IOS keeps the static route inactive in the routing table during normal conditions, activating it only if the primary EIGRP path fails.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing source.
Internal EIGRP has a default Administrative Distance of 9090.
Floating static routes rely on administrative distance values to determine primary vs. backup paths.
2
Determine the required Administrative Distance for the backup floating static route.
The administrative distance must be set to a value greater than 9090 (such as 9595).
Cisco IOS prefers routes with lower administrative distance values. Setting a value higher than 9090 keeps the static route out of the routing table while the EIGRP route is active.
3
Construct the static route CLI command including the destination IP, subnet mask, next-hop IP, and trailing AD parameter.
The resulting command is 'ip route 192.168.50.0 255.255.255.0 172.16.1.2 95'.
The trailing numeric argument defines the custom administrative distance for the static route.

Anahtar Kavram

Floating Static Route Configuration and Administrative Distance
Soru 410Soru →

Two Cisco routers, R1 and R2, are directly connected via an Ethernet link and configured for OSPFv2 single-area routing. An administrator notices that the OSPF neighbor state between R1 and R2 remains continuously stuck in the EXSTART state. Which configuration mismatch is the most likely cause of this issue?

Cevabı ve açıklamayı göster

Cevap: An IP Maximum Transmission Unit (MTU) mismatch on the interconnecting interfaces

Cevap

An IP Maximum Transmission Unit (MTU) mismatch on the interconnecting interfaces causes OSPF neighbors to become stuck in the ExStart or Exchange state.
During the ExStart state of OSPFv2 neighbor formation, routers elect a Master and Slave to sequence Database Description (DBD) packets. Cisco routers validate the IP MTU header field in incoming DBD packets against their local interface MTU. If an MTU mismatch exists, the larger-MTU router drops the smaller-MTU router's DBD packets (or vice versa), keeping the neighbor process continuously stuck in ExStart/Exchange.

Adım Adım Çözüm

1
Analyze OSPF neighbor establishment states
Identify that Hello parameter mismatches (Area ID, Hello/Dead timers, Authentication, Subnet Mask) prevent initial Hello acceptance and stop adjacencies in Down or Init states.
Basic parameters must match before Database Description (DBD) packet exchange begins.
2
Examine the ExStart/Exchange neighbor state requirements
In ExStart state, routers negotiate master/slave roles using DBD packets. By default, Cisco routers verify that the IP MTU in received DBD packets does not exceed their local interface MTU.
If MTU sizes differ between interfaces, DBD packet exchanges fail or are dropped, leaving the neighbor relationship stuck in ExStart or Exchange.

Anahtar Kavram

OSPF Neighbor States and MTU Mismatch Troubleshooting
Soru 411Soru →

A network administrator issues the `show ip route` command on a Cisco router and observes the following partial routing table output:

text
Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
O 10.20.0.0/16 [110/20] via 192.168.12.2, 00:15:10, GigabitEthernet0/0
D 10.20.30.0/24 [90/307200] via 192.168.23.3, 01:42:15, GigabitEthernet0/1
S 10.20.30.128/25 [1/0] via 192.168.34.4, GigabitEthernet0/2
O E2 10.0.0.0/8 [110/20] via 192.168.12.2, 00:05:22, GigabitEthernet0/0

Which TWO statements correctly describe the forwarding behavior and components of this routing table? (Select TWO.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: A packet destined for 10.20.30.140 is egressed via GigabitEthernet0/2 because 10.20.30.128/25 provides the longest prefix match.; For a packet destined to 10.20.30.150, the router prefers the static route (10.20.30.128/25) over the OSPF route (10.20.0.0/16) primarily due to prefix length rather than administrative distance.

Cevap

The router forwards a packet destined for 10.20.30.140 out GigabitEthernet0/2 due to the longest prefix match (/25), and it evaluates prefix length prior to Administrative Distance when choosing between 10.20.30.128/25 and 10.20.0.0/16 for host 10.20.30.150.
Routing table lookups prioritize the Longest Prefix Match (most specific subnet mask). For 10.20.30.140, the /25 route matches and is more specific than /24, /16, or /8, directing traffic to GigabitEthernet0/2. Similarly, prefix specificity overrides administrative distance when comparing non-identical prefix lengths such as /25 versus /16.

Adım Adım Çözüm

1
Parse the bracketed notation [AD/Metric] for Cisco routing entries.
In [90/307200], Administrative Distance is 90 and the composite metric is 307200.
Distinguishes Administrative Distance from protocol metrics.
2
Evaluate the IP destination 10.20.30.140 against candidate routing table entries.
Matches 10.0.0.0/8, 10.20.0.0/16, 10.20.30.0/24, and 10.20.30.128/25 (valid host range 10.20.30.129–10.20.30.254).
Identifies all candidate routes containing the destination IP address.
3
Apply the Longest Prefix Match (LPM) rule.
Selects 10.20.30.128/25 over shorter prefixes (/24, /16, /8), routing out GigabitEthernet0/2.
Prefix length length determines matching priority before administrative distance is ever evaluated for unequal prefixes.

Anahtar Kavram

Routing Table Components and Longest Prefix Match Determination
Soru 412Soru →

Four Cisco routers (R1, R2, R3, and R4) are connected to a single Layer 2 Ethernet switch on the 10.1.1.0/24 broadcast multi-access network segment. All four routers run OSPFv2 in Area 0 and are powered on simultaneously. Their interface OSPF priorities and OSPF Router IDs are configured as follows:

- R1: Router ID 192.168.100.1, Interface Priority = 0
- R2: Router ID 10.1.1.20, Interface Priority = 100
- R3: Router ID 172.16.50.1, Interface Priority = 100
- R4: Router ID 10.1.1.40, Interface Priority = 10

Which router is elected as the Designated Router (DR) and which router is elected as the Backup Designated Router (BDR) for this multi-access segment?

Cevabı ve açıklamayı göster

Cevap: R3 is elected as DR, and R2 is elected as BDR.

Cevap

R3 is elected as Designated Router (DR), and R2 is elected as Backup Designated Router (BDR).
The correct response identifies R3 as DR and R2 as BDR. In OSPFv2 broadcast multi-access networks, any router with an interface priority of 0 is strictly excluded from becoming a DR or BDR (relegated to DROTHER status). Thus, R1 is ineligible despite having the highest Router ID. Among the eligible routers (R2, R3, and R4), R2 and R3 share the highest priority (100). The tie is broken by comparing Router IDs; R3 (172.16.50.1) is higher than R2 (10.1.1.20), making R3 the DR. R2 is then elected as BDR because its priority (100) is higher than R4's priority (10).

Adım Adım Çözüm

1
Filter out disqualified routers based on OSPF interface priority.
R1 has an OSPF priority of 0, which makes it ineligible to participate in DR/BDR elections (it remains DROTHER). Eligible candidates are R2 (Priority 100), R3 (Priority 100), and R4 (Priority 10).
An interface priority of 0 explicitly prevents a router from becoming a DR or BDR regardless of its Router ID.
2
Determine the Designated Router (DR) using priority and Router ID rules.
R2 and R3 have the highest priority value (100). Comparing Router IDs, R3's Router ID (172.16.50.1) is numerically higher than R2's Router ID (10.1.1.20). R3 is selected as DR.
OSPF DR election first chooses the candidate with the highest priority. If priorities tie, it chooses the candidate with the highest Router ID.
3
Determine the Backup Designated Router (BDR) from the remaining eligible candidates.
Remaining candidates are R2 (Priority 100) and R4 (Priority 10). R2 has the higher priority, so R2 is selected as BDR.
After DR selection, the BDR is chosen using the same highest-priority and highest-Router-ID criteria among remaining eligible routers.

Anahtar Kavram

OSPFv2 DR/BDR Election Precedence and Priority 0 Disqualification
Soru 413Soru →

An administrator inspects the OSPFv2 interface settings on router HQ-R1 and observes a Hello interval of 10 seconds and a Dead interval of 40 seconds on interface GigabitEthernet0/1 (10.0.12.1/24, Area 0). On the directly connected router BR-R1 interface GigabitEthernet0/1 (10.0.12.2/24), OSPFv2 is configured in Area 0 with a Hello interval of 15 seconds and a Dead interval of 60 seconds. What is the outcome of the OSPFv2 neighbor relationship between HQ-R1 and BR-R1?

Cevabı ve açıklamayı göster

Cevap: The routers fail to establish a neighbor relationship, and neither router accepts the other as a valid neighbor.

Cevap

The routers fail to establish a neighbor relationship because OSPF Hello and Dead timer intervals must match on directly connected interfaces.
For two routers to form an OSPFv2 neighbor adjacency, several parameters in their Hello packets must match: Area ID, Subnet Mask, Hello Interval, Dead Interval, Stub Area Flag, and Authentication. Because HQ-R1 has a Hello/Dead timer configuration of 10s/40s while BR-R1 has 15s/60s, the Hello packets received by each router fail validation and are discarded, preventing any neighbor relationship from forming.

Adım Adım Çözüm

1
Analyze OSPF Hello packet parameter requirements for neighbor adjacency.
Identified that Hello interval, Dead interval, Area ID, Subnet Mask, and Authentication parameters must match in Hello packets.
OSPF routers drop incoming Hello packets if any mandatory Hello packet fields do not match the local configuration.
2
Compare the configured OSPF timer values between HQ-R1 and BR-R1.
HQ-R1 uses Hello/Dead of 10s/40s while BR-R1 uses Hello/Dead of 15s/60s.
The mismatched Hello (10s vs 15s) and Dead (40s vs 60s) intervals prevent packet validation.
3
Determine the resulting OSPF neighbor state.
No neighbor state is formed.
Because Hello packets are dropped upon receipt, neither router moves past the Down state for this peer.

Anahtar Kavram

OSPFv2 Mandatory Neighbor Adjacency Parameters
Soru 414Soru →

A network engineer is configuring an IPv4 static route on router HQ to reach the destination subnet 172.16.40.0/24172.16.40.0/24. Router HQ connects to the next-hop router over an Ethernet broadcast multi-access segment via interface GigabitEthernet0/1. The engineer enters the command `ip route 172.16.40.0 255.255.255.0 GigabitEthernet0/1` without specifying the next-hop IP address. Which operational issue will occur on router HQ as a result of configuring only the exit interface on a multi-access link?

Cevabı ve açıklamayı göster

Cevap: The router treats the destination network as directly connected and sends an ARP request for every destination IP address in the 172.16.40.0/24 subnet, causing ARP table bloat and performance degradation.

Cevap

The router treats the destination network as directly connected and sends an ARP request for every destination IP address in the 172.16.40.0/24 subnet, causing ARP table bloat and performance degradation.
Specifying only an exit interface on a broadcast multi-access link (like Ethernet) causes the router to treat the remote prefix as directly connected. When forwarding traffic, the router issues an ARP request for every individual destination IP within that prefix. This relies heavily on proxy ARP from the next-hop router, causing unnecessary ARP broadcast traffic and consuming significant Memory/CPU resources due to ARP cache growth.

Adım Adım Çözüm

1
Analyze static route exit interface behavior on broadcast networks.
When a static route specifies only a multi-access exit interface (such as Ethernet), Cisco IOS assumes the destination network resides directly on that interface segment.
Directly connected interface routes prompt the router to attempt Layer 2 MAC address resolution for every individual target destination IP address.
2
Evaluate layer 2 address resolution mechanics (ARP).
Router HQ generates an ARP request broadcast for each unique IP address in the 172.16.40.0/24172.16.40.0/24 network.
Without a explicit next-hop IP specified in the route, the router relies on proxy ARP from the neighboring router, creating large ARP tables and high broadcast overhead.

Anahtar Kavram

Directly Attached Static Routes on Multi-Access Ethernet Links
Tahmini Süre:1m 30s
Soru 415Soru →

Arrange the Cisco Hot Standby Router Protocol (HSRP) router states in the correct sequential order from initial interface startup to the active forwarding role.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence of HSRP state transitions from startup to active forwarding is: Initial state, Listen state, Speak state, Standby state, and Active state.
HSRP router state transitions follow a strict logical progression: Initial (startup), Listen (receives Hello packets), Speak (sends Hello packets and joins election), Standby (selected as candidate backup), and Active (forwards virtual IP traffic).

Adım Adım Çözüm

1
Identify the initialization state.
The router starts in the Initial state.
An interface must be enabled and initialized before any protocol messages are processed.
2
Determine the discovery phase.
The router transitions to the Listen state.
In the Listen state, the router receives Hello packets from existing group members without sending its own.
3
Identify the election participation phase.
The router moves to the Speak state.
The router sends periodic Hello messages to compete for active or standby router roles.
4
Determine the backup role assignment.
The router enters the Standby state.
The router is designated as the candidate to take over if the active router fails.
5
Identify the primary forwarding role.
The router reaches the Active state.
The elected router actively forwards frames destined to the virtual MAC and virtual IP address.

Anahtar Kavram

HSRP Router State Machine Sequence
Soru 416Soru →

A network administrator is evaluating the protocol mechanics and default operational behaviors of HSRPv2 and VRRPv2 across an enterprise distribution layer. Which two statements accurately describe the functional differences in preemption, virtual IP assignment, or virtual MAC addressing between HSRP and VRRP? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: VRRP permits configuring the virtual IP address to match the physical IP address assigned to an interface, whereas HSRP requires the virtual IP address to be an unassigned address within the local subnet.; VRRP enables preemption by default for participating routers, whereas HSRP requires preemption to be explicitly configured on candidate standby routers.

Cevap

The correct statements are that VRRP permits configuring the virtual IP address to match a physical IP address (IP address owner) while HSRP requires a unique IP, and VRRP enables preemption by default whereas HSRP requires explicit preemption configuration.
VRRP supports IP address ownership, allowing the virtual IP address to be identical to the primary physical IP address of an interface (which automatically assigns priority 255 to that router). HSRP does not support this and mandates that the virtual IP address must be an unused IP on the subnet. Additionally, VRRP preemption is enabled by default, whereas HSRP requires manual preemption configuration.

Adım Adım Çözüm

1
Analyze virtual IP assignment rules for HSRP vs VRRP
VRRP supports IP address ownership where the Master router's physical interface IP is used as the virtual IP (priority becomes 255). HSRP requires the virtual IP to be a separate, distinct IP address not assigned to any physical interface in the subnet.
Determines the validity of virtual IP configuration options.
2
Analyze default preemption mechanics across both protocols
VRRP has preemption enabled by default with a default priority of 100. HSRP has preemption disabled by default, meaning a higher-priority router will not take over the Active role unless 'standby preempt' is explicitly configured.
Identifies procedural configuration differences for failover behavior.
3
Verify virtual MAC address allocations for HSRPv2 and VRRPv2
VRRPv2 uses 0000.5E00.01xx0000.5E00.01xx. HSRPv1 uses 0000.0C07.ACxx0000.0C07.ACxx, and HSRPv2 uses 0000.0C9F.Fxxx0000.0C9F.Fxxx.
Evaluates MAC range precision to rule out inverted options.

Anahtar Kavram

HSRP vs VRRP Operational & Architectural Comparison
Soru 417Soru →

A network administrator is configuring Cisco HSRP group 5 on interface GigabitEthernet0/0 of a primary router. The interface is assigned the physical IPv4 address 10.1.10.2/24. When executing the command `standby 5 ip 10.1.10.2`, the router rejects the configuration. Which statement correctly explains why Cisco IOS rejects this command?

Cevabı ve açıklamayı göster

Cevap: HSRP requires the virtual IPv4 address to be unique and not match the physical IP address of any participating router interface.

Cevap

HSRP requires the virtual IPv4 address to be unique and not match the physical IP address of any participating router interface.
In HSRP, the virtual IPv4 address shared by the redundancy group must be a unique IP address in the local subnet that is not assigned as the physical interface address of any member router. When a network administrator attempts to assign an existing physical IP as the HSRP virtual IP, Cisco IOS rejects the command.

Adım Adım Çözüm

1
Analyze the HSRP virtual IP address configuration rule in Cisco IOS.
In HSRP (both v1 and v2), the virtual IP address must be a separate, unused IP address within the local primary IP subnet.
Cisco IOS explicitly blocks assigning a router's physical interface IP address as the HSRP virtual IP address to avoid ARP and routing conflicts.
2
Compare HSRP behavior with VRRP.
Unlike VRRP (which permits an IP Address Owner where the virtual IP matches the physical IP), HSRP rejects physical IP assignment.
Understanding protocol differences prevents misconfiguration errors on Cisco routers.

Anahtar Kavram

HSRP Virtual IP Address Assignment Rules
Soru 418Soru →

Match each OSPFv2 interface scenario or configuration on the left to its corresponding election behavior or timer characteristics on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

GigabitEthernet interface manually configured with 'ip ospf network point-to-point'
Ethernet interface configured with 'ip ospf priority 0' on a broadcast multi-access segment
Physical main interface configured for Frame Relay with default OSPF network type settings
Interface with 'ip ospf priority 200' connected to an active broadcast segment where a router with priority 100 is already the operational DR

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

The correct pairings are: 1) GigabitEthernet interface with 'ip ospf network point-to-point' matches 'Uses 10-second Hello / 40-second Dead timers and dynamically forms adjacencies without electing a DR or BDR.'; 2) Ethernet interface with 'ip ospf priority 0' matches 'Remains in the DROTHER state and is completely excluded from participating in DR/BDR elections regardless of Router ID.'; 3) Frame Relay main interface with default OSPF network type matches 'Defaults to Non-Broadcast (NBMA) mode using 30-second Hello / 120-second Dead timers and requires manual unicast neighbor statements.'; 4) Interface with priority 200 added to a segment with an active DR (priority 100) matches 'Does not preempt the operational DR upon initialization, assuming BDR or DROTHER status until an election event occurs.'
Each OSPF network type and interface parameter dictates distinct neighbor discovery methods, timer values, and election roles. Converting a broadcast interface to point-to-point maintains 10-second timers while removing DR/BDR election. Setting priority to 0 explicitly forces a DROTHER state. Default Frame Relay main interfaces employ NBMA mode with 30-second timers requiring unicast neighbor commands. Finally, introducing a high-priority router to a segment with an existing active DR honors OSPF's non-preemptive election rule.

Adım Adım Çözüm

1
Analyze OSPF network type override on broadcast interfaces.
Configuring 'ip ospf network point-to-point' on a broadcast interface (such as GigabitEthernet) instructs OSPF to treat the link logically as point-to-point. This retains the 10/40 second timers but suppresses DR/BDR election.
Point-to-point interfaces only connect two routers, making DR/BDR election unnecessary.
2
Evaluate the effect of interface priority 0.
An OSPF interface priority of 0 explicitly disqualifies the router interface from becoming a DR or BDR, locking its state into DROTHER.
Priority 0 is a reserved value designed specifically to prevent specific routers from taking on DR/BDR responsibilities.
3
Determine default behavior on Non-Broadcast Multi-Access (NBMA) media.
Frame Relay main interfaces default to the Non-Broadcast (NBMA) OSPF network type, which has 30-second Hello / 120-second Dead timers and does not send multicast Hello packets.
NBMA interfaces support multiple access without native broadcast/multicast capability, requiring static unicast neighbor configuration.
4
Analyze non-preemptive DR/BDR election mechanics.
When a router boots or connects to an existing multi-access network with an established DR, it accepts the existing DR and BDR regardless of its own interface priority.
DR/BDR elections in OSPF are non-preemptive to maintain routing stability and prevent unnecessary adjacency updates.

Anahtar Kavram

OSPFv2 Network Types, Timers, Priority Exclusions, and Non-preemptive Election Behavior
Soru 419Soru →

A network administrator is evaluating First Hop Redundancy Protocols (FHRP) for deployment across campus gateways. Which two statements correctly describe default operational characteristics of HSRPv1 compared to VRRPv2?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: VRRP enables router preemption by default, whereas HSRP requires preemption to be explicitly configured under interface settings.; HSRP designates redundancy roles as Active and Standby, whereas VRRP uses Master and Backup to define router states.

Cevap

VRRP enables preemption by default while HSRP requires explicit preemption configuration, and HSRP uses Active/Standby role terminology while VRRP uses Master/Backup.
VRRP has preemption enabled by default and uses Master/Backup role terminology, whereas HSRP has preemption disabled by default and uses Active/Standby role terminology.

Adım Adım Çözüm

1
Evaluate preemption default settings for HSRP and VRRP
VRRP preemption is enabled by default; HSRP preemption is disabled by default.
By protocol specification, VRRP automatically preempts lower-priority master routers unless preemption is manually disabled, whereas HSRP requires interface preemption syntax.
2
Examine operational role terminology across both protocols
HSRP uses Active and Standby; VRRP uses Master and Backup.
This aligns with RFC standards for VRRP compared to Cisco proprietary HSRP conventions.

Anahtar Kavram

First Hop Redundancy Protocols (HSRP and VRRP) default behavior comparison
Soru 420Soru →

Four Cisco routers (R1, R2, R3, and R4) are connected to a single Layer 2 Ethernet switch on the 192.168.1.0/24 subnet and configured for OSPFv2 single-area routing in Area 0. R1 and R2 have their OSPF interface priorities set to 100 and 50, respectively. R3 and R4 both have their OSPF interface priorities configured as 0. All routers are booted simultaneously and reach steady-state OSPF convergence. What is the expected OSPF neighbor state between R3 and R4 when executing the `show ip ospf neighbor` command on R3?

Cevabı ve açıklamayı göster

Cevap: 2WAY/DROTHER, because routers configured with a priority of 0 only build full adjacencies with the DR and BDR on broadcast multi-access networks.

Cevap

The expected OSPF neighbor state between R3 and R4 is 2WAY/DROTHER because DROTHER routers on a broadcast multi-access network form full adjacencies only with the DR and BDR, remaining in the 2-WAY state with each other.
On a broadcast multi-access network (such as Ethernet), OSPF reduces protocol overhead by electing a Designated Router (DR) and Backup Designated Router (BDR). Routers configured with an interface priority of 0 (DROTHERs) build FULL neighbor adjacencies only with the DR and BDR. Between two DROTHER routers (in this scenario, R3 and R4), bidirectional communication is established via Hello packets, so their neighbor relationship settles permanently in the 2-WAY state (displayed as 2WAY/DROTHER). This is normal operating behavior.

Adım Adım Çözüm

1
Analyze the network type and OSPF priorities.
The network segment is Ethernet (broadcast multi-access). R1 (priority 100) becomes DR, R2 (priority 50) becomes BDR, while R3 and R4 (priority 0) become DROTHERs.
Setting the OSPF interface priority to 0 disqualifies a router from being elected as DR or BDR.
2
Determine OSPF adjacency rules on multi-access networks.
DROTHER routers form FULL adjacencies exclusively with the DR and BDR. Between two DROTHER routers (R3 and R4), the neighbor relationship stops at the 2-WAY state.
Limiting FULL adjacencies to DR/BDR minimizes Link State Advertisement (LSA) flooding and memory overhead on shared network segments.

Anahtar Kavram

OSPF Neighbor States and DR/BDR Adjacency Requirements on Multi-Access Networks
Tahmini Süre:1m 30s
ÖncekiSayfa 21 / 25Sonraki
IP Connectivity Alıştırma Soruları — Cisco CCNA — Sayfa 21 | Examkin