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Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 1481Soru →

Four OSPFv2 routers are connected to a shared Layer 2 Ethernet switch on the 192.168.10.0/24 broadcast multiaccess network in Area 0. The interface configurations and boot order are as follows:

1. First, Router R3 (Priority 1, Router ID 10.3.3.3) and Router R4 (Priority 2, Router ID 10.1.1.1) booted up and established an adjacency. R4 was elected as the Designated Router (DR) and R3 was elected as the Backup Designated Router (BDR).
2. Later, Router R1 (Priority 0, Router ID 10.10.10.10) and Router R2 (Priority 2, Router ID 10.2.2.2) joined the segment and established adjacencies with all routers.

If Router R4 suddenly suffers a power outage and drops offline, which routers will assume the roles of Designated Router (DR) and Backup Designated Router (BDR) on this network segment?

Cevabı ve açıklamayı göster

Cevap: Router R3 becomes the DR, and Router R2 becomes the BDR.

Cevap

Router R3 becomes the Designated Router (DR), and Router R2 becomes the Backup Designated Router (BDR).
When the active Designated Router (R4) fails, OSPF non-preemption rules mandate that the existing Backup Designated Router (R3) is automatically promoted to DR. An election is then held solely for the newly vacated BDR position. Between the remaining routers, R1 is ineligible due to its OSPF priority of 0, leaving R2 (Priority 2) as the sole eligible router to become BDR.

Adım Adım Çözüm

1
Evaluate initial state prior to failure.
R4 is DR (Priority 2) and R3 is BDR (Priority 1). When R1 (Priority 0) and R2 (Priority 2) join later, no preemption occurs. R4 remains DR and R3 remains BDR.
OSPF DR and BDR roles are non-preemptive once elected on a broadcast multiaccess segment.
2
Determine DR replacement when R4 fails.
R3 (the active BDR) immediately transitions to DR.
When an active DR fails, the existing BDR is automatically promoted to DR without triggering a brand new DR election from scratch.
3
Evaluate candidates for the vacant BDR role among remaining active routers (R1 and R2).
R1 is disqualified because its priority is 0 (`ip ospf priority 0`). R2 has priority 2 (> 0) and is eligible.
Routers with an OSPF priority of 0 are permanently excluded from DR/BDR elections and remain in DROTHER state.
4
Conclude final roles.
R3 is DR and R2 is elected as the new BDR.
R2 is the only remaining eligible router with a priority greater than 0.

Anahtar Kavram

OSPF DR/BDR election rules: Non-preemption, BDR promotion, and Priority 0 exclusion.
Tahmini Süre:2m 0s
Soru 1482Soru →

An administrator connects a router interface to a broadcast multiaccess Ethernet network running OSPFv2. The administrator executes the command `ip ospf priority 0` under the interface configuration mode. How will this router participate in the OSPF Designated Router (DR) and Backup Designated Router (BDR) election on this segment?

Cevabı ve açıklamayı göster

Cevap: It becomes completely ineligible to serve as a DR or BDR.

Cevap

The router becomes completely ineligible to serve as a DR or BDR on the network segment.
Configuring `ip ospf priority 0` explicitly disables a router's eligibility to participate in Designated Router (DR) and Backup Designated Router (BDR) elections on multiaccess network types. The router will always remain in the DROTHER state for that interface segment.

Adım Adım Çözüm

1
Evaluate the interface priority value
The command `ip ospf priority 0` sets the OSPF priority for the interface to 0.
In OSPFv2, interface priority determines DR/BDR election participation (default priority is 1).
2
Apply OSPF DR/BDR election rules for priority 0
A priority of 0 prevents the interface from ever becoming a DR or BDR.
Routers with a priority of 0 remain in the DROTHER state on multiaccess networks.

Anahtar Kavram

OSPF Interface Priority 0 Ineligibility
Soru 1483Soru →

A network administrator has deployed Cisco Lightweight Access Points (LAPs) in FlexConnect mode at a remote branch office connected via WAN to a centralized Wireless LAN Controller (WLC) at headquarters. The WAN link between the branch and headquarters suddenly fails, causing the APs to lose communication with the WLC. Which two statements accurately describe the operational behavior of the APs while in FlexConnect standalone mode? (Choose two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: WLANs configured for FlexConnect local switching continue to forward client data traffic locally at the branch.; WLANs configured for central switching cease forwarding client traffic because the CAPWAP data tunnel to the WLC is down.

Cevap

In FlexConnect standalone mode, WLANs configured for local switching continue forwarding client traffic locally at the branch, while WLANs configured for central switching stop forwarding traffic because the CAPWAP tunnel to the central WLC is unavailable.
When a FlexConnect AP loses its CAPWAP control tunnel to the centralized WLC, it enters standalone mode. In standalone mode, WLANs configured for local switching remain operational because traffic is mapped directly to local VLANs on the branch switch. Conversely, WLANs configured for central switching fail because client traffic must be encapsulated in CAPWAP and sent to the WLC, which is unreachable due to the WAN outage.

Adım Adım Çözüm

1
Analyze the impact of WLC unreachability on FlexConnect local switching WLANs.
Local switching allows the branch AP to handle 802.11 to 802.3 frame conversion locally, allowing existing and new locally authenticated client traffic to flow without WLC CAPWAP encapsulation.
FlexConnect was designed specifically for branch reliability so local resources remain accessible during WAN outages.
2
Analyze the impact of WLC unreachability on centrally switched WLANs.
Central switching requires data packets to be tunneled via CAPWAP to the WLC at headquarters. Without WAN reachability to the WLC, the CAPWAP data path is broken.
Data frames cannot be processed locally on centrally switched SSIDs.
3
Evaluate invalid assumptions regarding automatic AP mode switching or controller election.
Standard Local mode APs drop clients when WLC connectivity fails, and FlexConnect standalone APs do not act as local Wireless LAN Controllers.
AP operational modes are administratively defined and do not dynamically alter their fundamental architecture during fault conditions.

Anahtar Kavram

FlexConnect Standalone Mode vs Connected Mode Traffic Handling
Tahmini Süre:1m 30s
Soru 1484Soru →

A network engineer is selecting physical media and transceiver modules to establish a 1 Gbps backbone link between two switches located in different buildings separated by a distance of 400 meters. Which two transceiver and cabling combinations will successfully support a Gigabit Ethernet link across this distance? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: A 1000BASE-LX SFP transceiver connected using single-mode fiber-optic (SMF) cabling.; A 1000BASE-LX SFP transceiver connected using OM3 multimode fiber-optic (MMF) cabling with a mode-conditioning patch cord.

Cevap

The correct options are the 1000BASE-LX SFP transceiver with single-mode fiber (SMF) cabling, and the 1000BASE-LX SFP transceiver with OM3 multimode fiber (MMF) cabling using a mode-conditioning patch cord.
Both selected options meet or exceed the 400-meter distance constraint. 1000BASE-LX transceivers operating over single-mode fiber can transmit up to 5 kilometers. Additionally, 1000BASE-LX transceivers can achieve up to 550 meters over multimode fiber when paired with a mode-conditioning patch cord.

Adım Adım Çözüm

1
Identify the distance constraint and speed requirement from the scenario.
The link distance is 400 meters and the required bandwidth is 1 Gbps (Gigabit Ethernet).
Selection of transceivers and cable types depends directly on distance limits defined by IEEE 802.3 standards.
2
Evaluate copper cabling limitations.
Category 6a UTP (1000BASE-T) is limited to 100 meters total channel length.
Copper cabling cannot span 400 meters without active repeaters or switches in between.
3
Evaluate short-reach optical transceiver specifications (1000BASE-SX).
1000BASE-SX over OM1 (62.5/125 µm) MMF supports a maximum distance of 275 meters.
Short-wavelength optics (850 nm) attenuate faster over legacy multimode fiber cores.
4
Evaluate long-reach optical transceiver specifications (1000BASE-LX).
1000BASE-LX over SMF supports up to 5 km. 1000BASE-LX over laser-optimized MMF (using a mode-conditioning patch cord) supports up to 550 meters.
Long-wavelength optics (1310 nm) satisfy the 400-meter requirement across both SMF and suitably conditioned MMF media.

Anahtar Kavram

Gigabit Ethernet transceiver distance limits and fiber media specifications (1000BASE-LX vs 1000BASE-SX vs 1000BASE-T)
Soru 1485Soru →

A Cisco router receives an IPv4 unicast packet on an ingress interface and prepares to forward it toward its final destination. Place the sequential steps of the router's packet forwarding decision process in the correct chronological order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence starts with decapsulating the incoming Layer 2 frame, searching the routing table for candidate prefix matches, selecting the best match using Longest Prefix Match (LPM), determining the egress interface and next-hop IP, resolving the Layer 2 address of the next-hop device via ARP, and finally decrementing the TTL and encapsulating the packet into a new frame for transmission.
The router processes ingress packets sequentially: it first strips the Layer 2 frame to read the destination IP, searches the routing table, applies the Longest Prefix Match rule to pick the most specific network prefix, determines the next-hop IP and egress interface, resolves the next-hop Layer 2 MAC address, and finishes by decrementing TTL, updating the checksum, encapsulating the packet, and transmitting the frame.

Adım Adım Çözüm

1
Frame Ingress & Decapsulation
The router strips the Layer 2 frame header/trailer to inspect the Layer 3 destination IPv4 address.
Routing decisions occur at Layer 3, requiring packet header extraction.
2
Routing Table Candidate Lookup
Identifies all routes in the IPv4 routing table that contain the destination IP address.
All matching network entries must be collected before evaluating prefix specificity.
3
Longest Prefix Match Selection
The route with the longest subnet mask (most matching network bits) is selected as the forwarding path.
Longest Prefix Match is the primary criterion for route lookup selection during packet forwarding.
4
Egress Interface & Next-Hop Identification
Extracted destination next-hop IPv4 address and outgoing physical/logical interface.
The selected route specifies where to send the packet next.
5
Layer 2 Next-Hop Address Resolution
ARP table lookup retrieves the MAC address associated with the next-hop IP.
Data-link layer framing requires a destination hardware address on Ethernet media.
6
Header Modification, Encapsulation, and Egress Transmission
TTL is decremented, checksum recalculated, new Layer 2 header attached, and frame sent out egress port.
Prevents routing loops via TTL expiration and prepares frame for transit across the next physical link segment.

Anahtar Kavram

Router IPv4 Forwarding Decision Pipeline
Soru 1486Soru →

An administrator is configuring a backup floating static route on a Cisco router for destination network 10.50.0.0/1610.50.0.0/16. The primary path to this network is currently learned via EIGRP with an administrative distance of 90. Which `ip route` command correctly implements a backup static route via next-hop IP 192.168.100.2192.168.100.2 that takes effect only if the primary EIGRP route fails?

Cevabı ve açıklamayı göster

Cevap: ip route 10.50.0.0 255.255.0.0 192.168.100.2 95

Cevap

The command 'ip route 10.50.0.0 255.255.0.0 192.168.100.2 95' correctly configures a floating static route by specifying a higher Administrative Distance (95) than EIGRP (90).
The correct option uses valid Cisco IOS static route syntax with a standard subnet mask (255.255.0.0) and assigns an administrative distance of 95. Because 95 is higher than the primary EIGRP path AD of 90, the route remains inactive in the routing table until the primary EIGRP path becomes unavailable.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary dynamic routing protocol
EIGRP internal routes have a default Administrative Distance of 90.
Floating static routes must have an AD higher than the primary route's AD to remain inactive until the primary route fails.
2
Verify standard Cisco IOS IPv4 static routing CLI syntax
The correct format is 'ip route <destination-network> <subnet-mask> <next-hop-ip> [administrative-distance]'.
IPv4 static routes require dotted-decimal subnet masks rather than wildcard masks.
3
Select the command with a valid subnet mask and an AD greater than 90
An AD of 95 ensures the static route is floating and only populated in the routing table when the EIGRP route is withdrawn.
An AD of 95 is strictly greater than 90 and less than the default static route AD of 1 or backup limits.

Anahtar Kavram

Floating Static Route Administrative Distance Selection
Soru 1487Soru →

Two Cisco routers are directly connected via an Ethernet link and configured to run OSPFv2 in Area 0. Router A is configured with an OSPF Hello interval of 10 seconds, while Router B is configured with an OSPF Hello interval of 15 seconds. Which outcome will occur when the OSPF process runs between these two routers?

Cevabı ve açıklamayı göster

Cevap: The routers will fail to form a neighbor relationship because OSPF Hello intervals must match exactly.

Cevap

The routers will fail to form a neighbor relationship because OSPF Hello intervals must match exactly.
For two routers to establish an OSPFv2 neighbor adjacency, several parameters contained in OSPF Hello packets must match exactly. These include the Area ID, Subnet Mask, Hello/Dead intervals, Authentication parameters, and Stub Area flags. Because Router A is configured with a 10-second Hello timer and Router B with a 15-second Hello timer, the routers reject each other's Hello packets and fail to form an adjacency.

Adım Adım Çözüm

1
Identify the OSPF neighbor requirement being tested
OSPF neighbor adjacencies require key parameters inside Hello packets to match between directly connected interfaces.
OSPF routers exchange Hello packets to discover neighbors and verify compatibility before forming adjacencies.
2
Evaluate the configured parameters
Router A has a 10-second Hello interval, whereas Router B has a 15-second Hello interval.
Hello/Dead intervals are mandatory matching parameters in OSPFv2.
3
Determine the operational outcome
Because the Hello intervals differ, each router will drop the incoming Hello packets from the other router, preventing adjacency formation.
Timer mismatch blocks the transition from Init to 2-Way/Full state.

Anahtar Kavram

OSPFv2 Neighbor Adjacency Requirements (Hello/Dead Timers)
Soru 1488Soru →

A network engineer is configuring Port Address Translation (PAT) on a Cisco IOS router using a dynamic interface-based configuration. The engineer enters the following global configuration command to map inside addresses matched by Access List 10 to the GigabitEthernet0/1 interface:

`ip nat inside source list 10 interface GigabitEthernet0/1`

Which single Cisco IOS keyword must be added to the end of this command to allow multiple internal hosts to share the single public IP address using unique source port numbers?

Cevabı ve açıklamayı göster

Cevap: overload

Cevap

overload
The `overload` keyword instructs Cisco IOS to perform Port Address Translation (PAT). PAT enables multiple inside local IP addresses to share a single inside global IP address (such as a router's outside interface address) by distinguishing traffic flows with unique source port numbers.

Adım Adım Çözüm

1
Identify the goal of the configuration command.
The objective is to enable Port Address Translation (PAT) using the router interface's single public IPv4 address.
Without PAT enabled, dynamic NAT only performs 1-to-1 IP translations, which exhausts the single interface IP address after only one internal host translates.
2
Determine the required Cisco IOS command parameter for PAT.
Adding `overload` to the end of the `ip nat inside source` statement enables port-level multiplexing.
The `overload` keyword tells Cisco IOS to track Layer 4 TCP and UDP port numbers alongside IP addresses, allowing thousands of simultaneous internal connections on a single public IP.

Anahtar Kavram

Port Address Translation (PAT) Overload Keyword
Tahmini Süre:45s
Soru 1489Soru →

A network administrator is configuring Port Address Translation (PAT) on a Cisco IOS router to allow multiple internal hosts on the 192.168.1.0/24 subnet to share the single public IPv4 address assigned to the GigabitEthernet0/1 interface. The administrator enters the following CLI commands:

Router(config)# access-list 1 permit 192.168.1.0 0.0.0.255
Router(config)# ip nat inside source list 1 interface GigabitEthernet0/1

During testing, only the first internal host that generates outbound traffic successfully connects to the Internet. Subsequent traffic from all other internal hosts is dropped. Which configuration change resolves this issue and enables all internal hosts to share the interface IP address simultaneously?

Cevabı ve açıklamayı göster

Cevap: Append the overload keyword to the ip nat inside source list 1 interface GigabitEthernet0/1 command.

Cevap

Appending the overload keyword to the NAT configuration command resolves the issue by enabling Port Address Translation (PAT).
In Cisco IOS, specifying a NAT inside source list with an interface but without the overload keyword configures dynamic 1-to-1 NAT using only the IP address of that interface. Because only one IP address is available, only the first host receives a translation entry in the NAT table. Appending the overload keyword enables Port Address Translation (PAT), allowing the router to distinguish traffic from multiple internal hosts using unique source port numbers.

Adım Adım Çözüm

1
Analyze the existing NAT command
The command 'ip nat inside source list 1 interface GigabitEthernet0/1' configures dynamic 1-to-1 NAT without port multiplexing.
Without the 'overload' keyword, Cisco IOS binds the single IP address of GigabitEthernet0/1 to the first inside local IP address requesting translation.
2
Identify the cause of traffic drop for subsequent hosts
Once the single outside IP address is allocated to the first host, no additional public IP addresses are available in the pool.
Standard dynamic NAT requires one unique public IPv4 address per active internal host.
3
Apply the correction for Port Address Translation (PAT)
Executing 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' enables PAT.
The 'overload' keyword instructs the router to track source port numbers along with IP addresses, allowing up to 65,000+ simultaneous internal connections on a single public IP address.

Anahtar Kavram

Port Address Translation (PAT) Overload Keyword Requirement
Soru 1490Soru →

A network administrator is configuring Port Address Translation (PAT) on a Cisco IOS router. Internal private IP hosts defined in Access Control List 1 (ACL 1) must share the single public IPv4 address assigned to the GigabitEthernet0/0 interface when communicating with the internet. Which Cisco IOS global configuration command correctly enables PAT for this scenario?

Cevabı ve açıklamayı göster

Cevap: ip nat inside source list 1 interface GigabitEthernet0/0 overload

Cevap

The command 'ip nat inside source list 1 interface GigabitEthernet0/0 overload' correctly configures PAT using an egress interface's IPv4 address.
The command 'ip nat inside source list 1 interface GigabitEthernet0/0 overload' specifies that traffic matching ACL 1 coming from the inside interface should have its source address translated to the IP address configured on GigabitEthernet0/0. The inclusion of the 'overload' keyword enables Port Address Translation (PAT), allowing multiple internal devices to simultaneously share the single public IP address via layer 4 port tracking.

Adım Adım Çözüm

1
Identify the translation direction and source identifier.
Internal traffic is identified by ACL 1, requiring 'ip nat inside source list 1'.
Inside source NAT identifies traffic originating from the internal network for translation.
2
Specify the target public IP source.
The target is the address on interface GigabitEthernet0/0, using 'interface GigabitEthernet0/0'.
When a dedicated public IP pool is not available or the ISP dynamically assigns an interface IP, NAT maps traffic directly to that interface.
3
Enable port-level multiplexing (PAT).
Append the 'overload' keyword at the end of the statement.
The 'overload' keyword allows thousands of internal IP addresses to share a single public IP address by tracking unique TCP/UDP source port numbers.

Anahtar Kavram

Configuring Inside Source Port Address Translation (PAT) with an interface address
Soru 1491Soru →

An administrator observes the following command output on Router R2 regarding a broadcast multiaccess Ethernet segment:

text
R2# show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/DR 00:00:35 10.1.1.1 GigabitEthernet0/0
3.3.3.3 1 FULL/BDR 00:00:32 10.1.1.3 GigabitEthernet0/0
10.10.10.10 0 FULL/DROTHER 00:00:38 10.1.1.10 GigabitEthernet0/0

The administrator executes `clear ip ospf process` simultaneously across all routers on this segment to trigger a new election. Assuming all routers re-establish OSPF neighbor relationships at the same time, which router will be elected as the new Designated Router (DR) and why?

Cevabı ve açıklamayı göster

Cevap: Router 3.3.3.3 will be elected as DR because Router 10.10.10.10 is ineligible due to a priority of 0, and Router 3.3.3.3 has the highest Router ID among the eligible routers.

Cevap

Router 3.3.3.3 will be elected as DR because Router 10.10.10.10 is ineligible due to a priority of 0, and Router 3.3.3.3 has the highest Router ID among the eligible routers.
On multiaccess broadcast networks, OSPF DR/BDR elections evaluate interface priority first. A router configured with priority 0 is completely ineligible to become a DR or BDR. Among the remaining eligible routers (1.1.1.1, 2.2.2.2, and 3.3.3.3), all have equal priority (1), so the highest Router ID breaks the tie. Router 3.3.3.3 has the highest Router ID among eligible routers and is elected DR.

Adım Adım Çözüm

1
Evaluate OSPF interface priority values for election eligibility.
Router 10.10.10.10 has priority 0 and is disqualified from DR/BDR candidacy.
Setting the OSPF interface priority to 0 (`ip ospf priority 0`) makes a router completely ineligible to become DR or BDR.
2
Compare priority values of remaining candidate routers.
Router 1.1.1.1 (Pri 1), Router 2.2.2.2 (Pri 1), and Router 3.3.3.3 (Pri 1) are tied.
All remaining eligible routers share the default interface priority of 1.
3
Apply the tie-breaker criterion (highest OSPF Router ID).
Router 3.3.3.3 wins the DR role.
When eligible candidates have equal non-zero priority, the router with the numerically highest Router ID (3.3.3.3 > 2.2.2.2 > 1.1.1.1) is selected as DR.

Anahtar Kavram

OSPFv2 DR/BDR Election Criteria and Priority 0 Ineligibility
Soru 1492Soru →

A network engineer configures an OSPFv2 process on a router interface connected to a broadcast multiaccess Ethernet network. The engineer issues the command `ip ospf priority 0` on the interface. How does this specific priority configuration affect the router's role in the OSPF DR/BDR election process?

Cevabı ve açıklamayı göster

Cevap: The interface is strictly prohibited from participating in the election and remains in the DROTHER state.

Cevap

Setting an OSPF interface priority to 0 disqualifies the router from participating in elections, forcing its state to DROTHER.
In OSPFv2, interface priority ranges from 0 to 255. A priority of 0 specifically signifies that the router is disqualified from becoming either the Designated Router (DR) or the Backup Designated Router (BDR) on a multiaccess network segment. As a result, the interface transitions to and stays in the DROTHER state.

Adım Adım Çözüm

1
Evaluate the effect of the interface subcommand `ip ospf priority <0-255>` on multiaccess networks.
The default priority on multiaccess interfaces is 1.
Higher priority values are preferred during DR/BDR elections.
2
Determine the special significance of priority value 0.
A priority of 0 explicitly makes the interface ineligible to become DR or BDR.
This is a design mechanism used to prevent hub or low-capacity routers from accepting DR/BDR responsibilities.

Anahtar Kavram

OSPF Interface Priority 0 Selection Ineligibility
Tahmini Süre:45s
Soru 1493Soru →

A network administrator executes the command `show interfaces gigabitethernet0/2 switchport` on a Cisco Catalyst switch to troubleshoot a connectivity issue for an end-user device. The CLI output displays the following operational state:

text
Name: Gi0/2
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: trunk
Access Mode VLAN: 20 (VLAN0020)
Trunking Native Mode VLAN: 1 (default)

Which command must be configured on interface GigabitEthernet0/2 to force the port to operate as an access port in VLAN 20?

Cevabı ve açıklamayı göster

Cevap: switchport mode access

Cevap

The command `switchport mode access` must be configured on interface GigabitEthernet0/2.
The CLI output indicates that interface GigabitEthernet0/2 has an Administrative Mode of 'dynamic auto' and has negotiated an Operational Mode of 'trunk'. Even though an access VLAN of 20 is configured, access VLAN assignments only take effect when the operational mode is access. Executing `switchport mode access` under interface configuration mode statically sets the interface to access mode and disables trunking negotiation.

Adım Adım Çözüm

1
Analyze the CLI output for interface GigabitEthernet0/2
Administrative Mode is set to 'dynamic auto' and Operational Mode is currently operating as 'trunk'.
By default on many Cisco Catalyst switches, interfaces run Dynamic Trunking Protocol (DTP) in dynamic auto mode. If the connected device sends DTP frames or negotiates trunking, the interface operates as a trunk regardless of the configured access VLAN.
2
Determine the required command to override dynamic negotiation
Configuring `switchport mode access` under `interface GigabitEthernet0/2` forces the interface to operate statically as an access port.
Statically defining the port mode as access disables trunk negotiation for that port and activates the configured `switchport access vlan 20` setting.

Anahtar Kavram

Disabling DTP trunk negotiation by statically configuring access port mode with 'switchport mode access'.
Soru 1494Soru →

A network administrator evaluates an OSPFv2-enabled router interface on a multiaccess Ethernet network and issues the following Cisco IOS command:

text
Router1# show ip ospf interface GigabitEthernet0/1
GigabitEthernet0/1 is up, line protocol is up
Internet Address 192.168.10.1/24, Area 0
Process ID 1, Router ID 10.1.1.1, Network Type BROADCAST, Cost: 1
Trans Delay is 1 sec, State DROTHER, Priority 0
Designated Router (ID) 10.4.4.4, Interface address 192.168.10.4
Backup Designated Router (ID) 10.3.3.3, Interface address 192.168.10.3
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Which two statements accurately describe the operational status and election behavior of this router on the segment? (Choose two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The router is completely ineligible to be elected as Designated Router (DR) or Backup Designated Router (BDR) because its interface priority is set to 0.; If the active Designated Router (10.4.4.4) fails, the Backup Designated Router (10.3.3.3) will be promoted to Designated Router while this router remains a DROTHER.

Cevap

The correct statements are that the router is completely ineligible for DR/BDR election due to an interface priority of 0, and that if the active DR fails, the active BDR will be promoted to DR while this router remains a DROTHER.
In OSPFv2 broadcast multiaccess networks, setting an interface priority to 0 makes the router completely ineligible for Designated Router (DR) or Backup Designated Router (BDR) roles, forcing it into the DROTHER state. Furthermore, when an active DR fails, the existing BDR is promoted to DR. Because this router's priority is 0, it cannot participate in the election for the replacement BDR and remains a DROTHER.

Adım Adım Çözüm

1
Analyze interface priority settings from the command output.
The interface priority is configured as Priority 0.
In OSPFv2, an interface priority of 0 signifies that the router is ineligible to participate in DR or BDR elections.
2
Determine the router's current state and election behavior.
The state is DROTHER, and it will remain in this state even if the active DR fails.
Upon DR failure, the current BDR (10.3.3.3) takes over as DR. A new BDR election occurs among eligible routers (priority > 0). Since this router has priority 0, it cannot become the new BDR.
3
Evaluate preemption and alternative network types.
OSPF DR/BDR elections are non-preemptive, and Point-to-Point links suppress DR/BDR elections entirely.
Modifying priorities does not trigger preemption on broadcast links, and changing to Point-to-Point eliminates DR/BDR roles entirely.

Anahtar Kavram

OSPFv2 DR/BDR Election Rules and Priority 0 Ineligibility
Soru 1495Soru →

An engineer configures a static backup route on router R1 for remote destination subnet 172.22.50.0/24172.22.50.0/24. The primary path to this subnet is learned dynamically via OSPFv2. During baseline verification, the engineer discovers that traffic destined for 172.22.50.0/24172.22.50.0/24 routes over the backup WAN circuit even though the primary OSPF link is active and in the FULL state. Which configuration issue on router R1 explains why the backup route is active in the routing table?

Cevabı ve açıklamayı göster

Cevap: The static route was configured without specifying a custom administrative distance, causing it to use the default administrative distance of 1, which beats the OSPF administrative distance of 110.

Cevap

The static route was configured without specifying a custom administrative distance, causing it to use the default administrative distance of 1, which beats the OSPF administrative distance of 110.
In Cisco IOS, static routes configured without an explicit administrative distance inherit the default value of 1. Because routers populate the IP routing table by choosing the path with the lowest administrative distance when multiple sources report the same prefix, a static route with AD 1 will take precedence over an OSPF route with AD 110. To act as a floating static route, the static route's administrative distance must be manually set higher than the primary routing protocol's AD (for example, setting AD to 115 or 120).

Adım Adım Çözüm

1
Identify the administrative distance (AD) of the primary dynamic routing protocol.
OSPFv2 has a default administrative distance of 110.
Administrative distance measures the trustworthiness of a routing source. Lower values are preferred.
2
Analyze default static route behavior when no administrative distance parameter is specified.
Cisco IOS assigns a default administrative distance of 1 to static routes.
Because 1 is lower than 110, the router chooses the static route as more believable than the OSPF route.
3
Determine the requirement for a floating static route.
To float behind OSPF, the static route must be configured with an administrative distance strictly greater than 110 (e.g., 120).
Omitting the AD parameter causes the static route to become the active primary path instead of a floating backup.

Anahtar Kavram

Floating Static Route Administrative Distance Configuration
Tahmini Süre:2m 0s
Soru 1496Soru →

An administrator executes the `show ip route` command on a Cisco enterprise router, resulting in the following partial routing table output:

text
Codes: C - connected, S - static, O - OSPF, D - EIGRP

Gateway of last resort is not set

10.250.0.0/16 is variably subnetted, 4 subnets, 4 masks
O 10.250.16.0/20 [110/20] via 192.168.1.2, 00:14:22, GigabitEthernet0/0
D 10.250.16.0/24 [90/307200] via 192.168.1.6, 00:05:10, GigabitEthernet0/1
S 10.250.16.128/26 [1/0] via 192.168.1.10
C 10.250.16.128/27 is directly connected, GigabitEthernet0/2

Which two statements accurately describe how the router interprets these components and forwards traffic? (Select two.)

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Cevap: A packet destined for 10.250.16.130 is egressed via GigabitEthernet0/2 because it matches the route with the longest prefix length (/27).; The bracketed output [90/307200] specifies an Administrative Distance of 90 and a routing metric of 307200 for the EIGRP-learned subnet.

Cevap

Packets for 10.250.16.130 match the /27 route out GigabitEthernet0/2 due to the longest prefix match rule, and the bracketed entry [90/307200] defines Administrative Distance as 90 and Metric as 307200.
When forwarding an IP packet, the router selects the route that matches the destination IP address with the longest prefix length (most specific subnet mask). Destination 10.250.16.130 fits within 10.250.16.128/27, which is a longer prefix than /26, /24, or /20, making GigabitEthernet0/2 the correct egress path. Additionally, Cisco IOS displays administrative distance and metric formatted as [Administrative Distance/Metric], meaning [90/307200] denotes an AD of 90 and a metric of 307200.

Adım Adım Çözüm

1
Evaluate destination IP 10.250.16.130 against all matching prefix ranges in the routing table.
10.250.16.130 falls into 10.250.16.0/20, 10.250.16.0/24, 10.250.16.128/26, and 10.250.16.128/27.
The router determines all candidates that enclose the destination IP address.
2
Apply the Longest Prefix Match (LPM) rule to select the best forwarding path among matching routes.
The subnet 10.250.16.128/27 has the longest prefix length (/27 > /26 > /24 > /20) and is chosen, forwarding the packet out GigabitEthernet0/2.
Longest prefix match always takes precedence over administrative distance or metric when forwarding IP traffic.
3
Decode the standard Cisco IOS bracketed routing table fields [AD/Metric].
For [90/307200], 90 is the Administrative Distance (EIGRP internal default) and 307200 is the EIGRP composite metric.
In Cisco IOS output format [X/Y], the first integer represents Administrative Distance and the second integer represents the protocol metric.

Anahtar Kavram

Routing Table Interpretation and Longest Prefix Match Forwarding Logic
Soru 1497Soru →

Match each OSPFv2 network type on the left with its corresponding DR/BDR election behavior, neighbor discovery method, and default Hello/Dead timers on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Broadcast
Point-to-Point
Point-to-Multipoint
Non-Broadcast Multi-Access (NBMA)

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Broadcast pairs with DR/BDR election, dynamic multicast discovery, and 10s/40s timers. Point-to-Point pairs with suppressed DR/BDR election, dynamic multicast discovery, and 10s/40s timers. Point-to-Multipoint pairs with suppressed DR/BDR election, dynamic multicast discovery, and 30s/120s WAN timers. NBMA pairs with DR/BDR election, manual unicast neighbor configuration, and 30s/120s WAN timers.
The matching correctly pairs each OSPF network type with its operational attributes: Broadcast requires DR/BDR and uses 10s/40s timers with dynamic discovery; Point-to-Point bypasses DR/BDR and uses 10s/40s timers with dynamic discovery; Point-to-Multipoint bypasses DR/BDR but uses 30s/120s WAN timers with dynamic discovery; NBMA requires DR/BDR, 30s/120s WAN timers, and manual unicast neighbor definitions.

Adım Adım Çözüm

1
Analyze DR/BDR election requirements for each OSPF network type.
Broadcast and NBMA network types elect a DR/BDR. Point-to-Point and Point-to-Multipoint network types suppress DR/BDR elections.
DR/BDR elections are required on multi-access network types where all routers can reach each other directly to prevent n(n−1)/2n(n-1)/2 full adjacencies.
2
Determine neighbor discovery capabilities (Multicast vs. Unicast).
Broadcast, Point-to-Point, and Point-to-Multipoint dynamically discover neighbors using multicast address 224.0.0.5. NBMA requires manual unicast neighbor configuration.
Non-broadcast networks lack native multicast capability, requiring the administrator to manually define neighbor IP addresses under the OSPF router process.
3
Evaluate default OSPF Hello and Dead timers for each network type.
High-speed LAN types (Broadcast and Point-to-Point) use 10s Hello / 40s Dead timers. Slow WAN types (Point-to-Multipoint and NBMA) use 30s Hello / 120s Dead timers.
OSPF timer defaults are calibrated based on expected media speed and reliability.

Anahtar Kavram

OSPFv2 Network Types, DR/BDR Election Requirements, and Timer Defaults
Tahmini Süre:2m 0s
Soru 1498Soru →

A network administrator is evaluating OSPFv2 operations across different interface types on Cisco routers. Which two statements accurately describe the characteristics and behavior of the OSPFv2 point-to-point network type compared to the broadcast multiaccess network type? (Choose two.)

Geçerli olan tümünü seçin

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Cevap: OSPFv2 suppresses the election of a Designated Router (DR) and Backup Designated Router (BDR) on point-to-point interfaces.; Point-to-point interfaces use default Hello and Dead timers of 10 seconds and 40 seconds, matching default broadcast network timers.

Cevap

The two correct statements are that OSPFv2 does not elect a DR/BDR on point-to-point network types, and point-to-point network types use default Hello and Dead timers of 10 seconds and 40 seconds.
The statements confirming that OSPFv2 suppresses DR/BDR elections on point-to-point interfaces and that point-to-point interfaces use 10-second Hello / 40-second Dead timers are correct. On point-to-point links, only two routers exist, so full mesh adjacency overhead is not an issue, rendering DR/BDR roles redundant. Furthermore, standard Ethernet point-to-point links default to 10s/40s timers identical to broadcast multiaccess links.

Adım Adım Çözüm

1
Analyze DR/BDR election requirements across OSPF network types.
Broadcast multiaccess networks elect a DR and BDR to reduce adjacency overhead on shared segments. Point-to-point links connect exactly two devices, making DR/BDR elections unnecessary.
Recognizing that point-to-point interface mode bypasses DR/BDR selection is fundamental to OSPF network design.
2
Verify default timer values for OSPFv2 network types.
Both broadcast and point-to-point network types default to a Hello timer of 10 seconds and a Dead timer of 40 seconds (4 times the Hello interval).
Timer consistency across matching network types ensures neighbors form adjacencies without timer mismatches.

Anahtar Kavram

OSPFv2 Point-to-Point vs Broadcast Network Type Characteristics
Soru 1499Soru →

Refer to the following excerpt from a Cisco router's IPv4 routing table:

text
Gateway of last resort is 10.0.0.1 to network 0.0.0.0

O 192.168.10.0/24 [110/20] via 10.1.1.1, 00:05:12, GigabitEthernet0/0
D 192.168.10.32/28 [90/307200] via 10.2.2.2, 00:12:44, GigabitEthernet0/1
S 192.168.10.32/27 [1/0] via 10.3.3.3, 01:00:15, GigabitEthernet0/2
S* 0.0.0.0/0 [1/0] via 10.0.0.1, 02:15:00, GigabitEthernet0/3

Which next-hop IP address will the router select to forward a packet addressed to 192.168.10.38?

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Cevap: 10.2.2.2

Cevap

10.2.2.2
When an IP packet arrives, the router compares the destination address against all routing table entries. The route with the longest matching prefix (most specific subnet mask) is selected. Here, 192.168.10.32/28 has a prefix length of 28 bits, which is longer than /27, /24, or /0. Therefore, the router forwards the packet to 10.2.2.2.

Adım Adım Çözüm

1
Identify all candidate routes that encompass the target IP address 192.168.10.38
Candidate routes are 192.168.10.0/24 (range .0 - .255), 192.168.10.32/27 (range .32 - .63), 192.168.10.32/28 (range .32 - .47), and 0.0.0.0/0.
Routing decisions are evaluated by first determining which entries contain the destination host IP.
2
Apply the Longest Prefix Match (LPM) rule among valid candidate routes
192.168.10.32/28 has the longest subnet mask length (/28 > /27 > /24 > /0).
Routers always prefer the most specific route (longest prefix length) regardless of protocol or administrative distance.
3
Determine the next-hop IP associated with the winning prefix
The entry 192.168.10.32/28 forwards via next-hop IP 10.2.2.2.
The matching routing table entry explicitly specifies 10.2.2.2 as its next-hop.

Anahtar Kavram

Longest Prefix Match (LPM)
Tahmini Süre:1m 30s
Soru 1500Soru →

During a network outage, a centralized Wireless LAN Controller (WLC) becomes completely unreachable from the campus network. Several Cisco Lightweight Access Points (LAPs) in the facility are configured in standard Local mode. How do these Local mode APs handle connected wireless clients while WLC connectivity is lost?

Cevabı ve açıklamayı göster

Cevap: They drop all client associations and stop forwarding data traffic because an active CAPWAP tunnel to the controller is required for operation.

Cevap

Local mode APs drop all client associations and stop forwarding data traffic because an active CAPWAP tunnel to the controller is required for operation.
In standard Local mode, a Cisco Lightweight Access Point routes all control and data traffic through CAPWAP tunnels back to the Wireless LAN Controller (centralized switching). If the WLC becomes unreachable, the CAPWAP tunnel collapses, causing the AP to drop all client associations, stop serving WLANs, and reboot/search for an accessible WLC.

Adım Adım Çözüm

1
Analyze the operational behavior of Cisco Lightweight Access Points in standard Local mode.
Local mode is the default AP mode where all wireless user traffic is encapsulated into CAPWAP data packets and sent directly to the Wireless LAN Controller (centralized switching).
Control and data plane functions rely entirely on the active CAPWAP connection between the AP and WLC.
2
Determine the outcome when the WLC becomes completely unreachable.
Without a responsive WLC, the CAPWAP control tunnel drops. The Local mode AP cannot process client frames locally nor manage client authentication.
Unlike FlexConnect mode, Local mode APs cannot operate in a standalone state.
3
Identify the correct impact on client connectivity.
The AP drops all associated clients and continuously attempts to discover and rejoin a WLC.
Wireless service is completely interrupted until WLC connectivity is restored.

Anahtar Kavram

Cisco Lightweight Access Point Local Mode vs FlexConnect Mode Behavior During WLC Outage
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