Examkin

Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 1501Soru →

A switch running Rapid PVST+ receives BPDUs across multiple active interfaces and must determine which port will assume the Root Port role for a specific VLAN. Place the decision criteria evaluated by the switch in the correct sequential order, starting from the first criterion evaluated to the last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence for selecting a Rapid PVST+ Root Port is: 1. Lowest cumulative Root Path Cost to the Root Bridge, 2. Lowest upstream neighbor Bridge ID (Sender BID), 3. Lowest upstream neighbor Port ID (Sender Port ID), 4. Lowest local Port ID on the receiving switch.
When selecting a Root Port, a Rapid PVST+ non-root switch evaluates received BPDU criteria in a strict hierarchical order: cumulative Root Path Cost first, followed by sender Bridge ID, sender Port ID, and finally local Port ID.

Adım Adım Çözüm

1
Evaluate path efficiency
Identify the interface with the lowest cumulative cost to reach the Root Bridge.
STP prioritizes path efficiency before comparing device or port identifiers.
2
Evaluate upstream device identity
If path costs are equal, compare the Bridge IDs of the neighboring switches sending the BPDUs.
Connecting to a neighbor with a lower Bridge ID takes precedence when costs match.
3
Evaluate upstream port identity
If connected via multiple links to the same upstream switch, compare the Port IDs (port priority + port number) transmitted by the neighbor.
The upstream switch's lower sending port ID breaks ties for parallel links to the same neighbor.
4
Evaluate local port identity
If all received BPDU fields are identical, compare the local receiving switch's Port IDs.
The local switch uses its own lowest port ID as the final deterministic tie-breaker.

Anahtar Kavram

Rapid PVST+ Root Port Selection Algorithm
Tahmini Süre:1m 30s
Soru 1502Soru →

A network administrator needs to create a new VLAN for isolated guest traffic (VLAN 80, named GUEST) on a Cisco Catalyst switch and configure interface GigabitEthernet0/12 as a static access port belonging to this VLAN. In what sequence should the administrator execute the CLI commands starting from Privileged EXEC mode?

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence starts with 'configure terminal' to enter global configuration mode, followed by 'vlan 80' to create the VLAN, 'name GUEST' to name it, 'interface GigabitEthernet0/12' to enter interface mode, 'switchport mode access' to define the port mode, and 'switchport access vlan 80' to assign the port to the VLAN.
Configuring a VLAN and access port requires following Cisco IOS mode hierarchy: starting in Privileged EXEC mode, entering Global Configuration mode via 'configure terminal', instantiating VLAN 80 with 'vlan 80', assigning its label with 'name GUEST', navigating to the target port via 'interface GigabitEthernet0/12', locking its operational state with 'switchport mode access', and assigning it to the newly created VLAN with 'switchport access vlan 80'.

Adım Adım Çözüm

1
Enter Global Configuration mode
Switch prompt changes to Switch(config)#
CLI commands for creating VLANs and accessing interfaces require global configuration context.
2
Create VLAN 80
Switch prompt changes to Switch(config-vlan)#
VLAN 80 must be created before naming or assigning interfaces to it.
3
Name the VLAN GUEST
VLAN 80 is assigned the name GUEST in the database
The name sub-command must be executed within config-vlan mode.
4
Select interface GigabitEthernet0/12
Switch prompt changes to Switch(config-if)#
Interface configuration mode is required to apply port-specific switchport commands.
5
Configure operational mode as access
DTP negotiation is disabled for trunking and port is forced to access mode
Disabling dynamic trunking negotiation ensures the port functions strictly as an access port.
6
Assign the interface to VLAN 80
Interface GigabitEthernet0/12 is placed into VLAN 80 broadcast domain
Associates untagged ingress frames on GigabitEthernet0/12 with VLAN 80.

Anahtar Kavram

Cisco IOS CLI command hierarchy and sequence for creating a VLAN and configuring an access port.
Tahmini Süre:1m 30s
Soru 1503Soru →

A network administrator needs to manually configure an IPv4 static route to the destination subnet 192.168.10.0/24192.168.10.0/24 using the next-hop IP address 10.1.1.210.1.1.2 on a Cisco IOS router, starting from user EXEC mode. Place the CLI commands and actions in the correct sequential order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence starts with entering privileged EXEC mode (`enable`), moving into global configuration mode (`configure terminal`), applying the static route command (`ip route 192.168.10.0 255.255.255.0 10.1.1.2`), and finally verifying the routing table entry (`show ip route static`) in privileged EXEC mode.
In Cisco IOS, configuration follows a strict hierarchy. User EXEC mode (`Router>`) must first be elevated to Privileged EXEC mode (`Router#`) using `enable`. Next, Global Configuration mode (`Router(config)#`) is accessed with `configure terminal`. The static route `ip route 192.168.10.0 255.255.255.0 10.1.1.2` is then entered. Finally, returning to Privileged EXEC mode permits running `show ip route static` to verify that the route is installed in the routing table.

Adım Adım Çözüm

1
Elevate privileges from User EXEC mode to Privileged EXEC mode.
Prompt changes from `Router>` to `Router#` after running `enable`.
Configuration commands cannot be executed directly from User EXEC mode.
2
Navigate to Global Configuration mode.
Prompt changes to `Router(config)#` after running `configure terminal`.
Static route configuration via `ip route` is a global configuration parameter.
3
Configure the IPv4 static route.
The command `ip route 192.168.10.0 255.255.255.0 10.1.1.2` is committed to running-config.
Specifies destination network prefix, subnet mask, and next-hop IP address.
4
Exit configuration mode and verify the routing table.
The `show ip route static` command displays `S 192.168.10.0/24 [1/0] via 10.1.1.2`.
Confirms the static route is installed in the IPv4 routing table successfully.

Anahtar Kavram

Cisco IOS CLI hierarchy navigation and static route command syntax
Soru 1504Soru →

Two Cisco routers, R1 and R2, are connected to a shared Ethernet switch on the 10.1.1.0/24 broadcast multiaccess network running OSPFv2 in Area 0. Router R1 initializes first with an OSPF interface priority of 1 and a Router ID of 1.1.1.1. Seeing no other routers during its Wait timer, R1 elects itself as the Designated Router (DR). Ten minutes later, Router R2 is booted on the segment with its connected interface configured with an OSPF priority of 100 and a Router ID of 2.2.2.2. Which OSPF role will R2 assume on this network segment once neighbor adjacency is fully established?

Cevabı ve açıklamayı göster

Cevap: Backup Designated Router (BDR), while R1 remains the Designated Router (DR)

Cevap

Router R2 will assume the Backup Designated Router (BDR) role, while Router R1 remains the Designated Router (DR).
In OSPFv2 broadcast multiaccess networks, DR/BDR elections are non-preemptive. Once a router establishes itself as the active Designated Router (DR), it retains that role even if another router with a higher interface priority or higher Router ID subsequently joins the segment. Because R1 was already serving as DR and no BDR was present, R2 is elected as the Backup Designated Router (BDR).

Adım Adım Çözüm

1
Analyze the state of the OSPF segment when R1 boots alone.
R1 boots first, waits for neighbor Hellos during the Wait timer, finds no other router, and elects itself as the active DR on the multiaccess Ethernet segment.
On a broadcast multiaccess network, if no DR is present and no other candidate responds, the first active router assumes the DR role.
2
Evaluate OSPF DR/BDR election behavior when R2 joins the network.
OSPF DR and BDR elections are non-preemptive. An active DR will not be unseated by a newly connected router, regardless of the new router's higher OSPF interface priority or Router ID.
Non-preemption prevents network instability and frequent SPF recalculations whenever routers reboot or join the segment.
3
Determine the specific role assigned to R2.
Because a DR already exists (R1) and no BDR is currently active, R2 fills the vacant BDR position.
R2 has an eligible priority (100>0100 > 0), making it eligible for the BDR role.

Anahtar Kavram

Non-preemptive nature of OSPFv2 DR/BDR elections on broadcast multiaccess networks
Tahmini Süre:1m 15s
Soru 1505Soru →

A Cisco router receives an IPv4 packet destined for host 172.16.5.45172.16.5.45. The routing table contains a static route configured with a next-hop IP address: `ip route 172.16.5.0 255.255.255.0 10.0.0.2`. In what chronological order does the router execute the forwarding decision and recursive lookup process to transmit this packet? Place the steps in order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct operational order begins with inspecting the packet header to extract the destination IPv4 address, followed by executing a longest prefix match in the routing table. Next, because the matching static route points to a next-hop IP rather than an exit interface, the router performs a recursive lookup to find the egress interface. Finally, the router resolves the next-hop MAC address via ARP, encapsulates the packet into a Layer 2 frame, and transmits it.
Packet processing follows a strict sequential pipeline in Cisco IOS: Layer 3 packet destination extraction → Longest Prefix Match routing table lookup → Recursive resolution of the next-hop IP address to an exit interface → ARP MAC address resolution and Layer 2 frame transmission.

Adım Adım Çözüm

1
Packet Ingress & Header Inspection
Destination IP address 172.16.5.45172.16.5.45 is extracted.
Routing decisions require identifying the target host IP in the IP packet header.
2
Primary Routing Table Lookup
The static route entry `172.16.5.0/24 via 10.0.0.2` is selected based on Longest Prefix Match.
Cisco IOS routes traffic using the most specific matching network mask in the routing table.
3
Recursive Next-Hop Lookup
The next-hop IP 10.0.0.210.0.0.2 is resolved to a directly connected network and outbound interface.
Static routes configured solely with a next-hop IP require an additional lookup step to identify which physical or logical interface sends the traffic.
4
Layer 2 Encapsulation & Transmission
ARP table yields the destination MAC address for 10.0.0.210.0.0.2, frame is rewritten and transmitted.
Multi-access interfaces (like Ethernet) need a specific destination Layer 2 MAC address to transmit the packet.

Anahtar Kavram

IPv4 Static Route Recursive Lookup & Packet Forwarding Logic
Soru 1506Soru →

Match each Cisco Lightweight Access Point (LAP) operational mode to its correct primary functional description.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

FlexConnect Mode
Sniffer Mode
SE-Connect Mode
Rogue Detector Mode

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

FlexConnect Mode matches local traffic switching during WAN outages; Sniffer Mode matches capturing raw 802.11 frames for packet analyzers; SE-Connect Mode matches sending raw RF data to spectrum analysis tools; Rogue Detector Mode matches correlating wireless and wired MAC addresses to find unauthorized devices.
Each mode serves a distinct operational purpose: FlexConnect allows branch local traffic switching without reliance on a persistent CAPWAP tunnel for user data. Sniffer mode captures raw 802.11 frames to send to network analysis tools like Wireshark. SE-Connect streams raw physical spectrum metrics to software tools like Cisco Spectrum Expert. Rogue Detector correlates MAC addresses from wired switch ports and rogue AP broadcasts to detect connected unauthorized access points.

Adım Adım Çözüm

1
Identify the primary purpose of FlexConnect mode in remote branch environments.
FlexConnect allows local data switching and client authentication even if the WAN tunnel to the controller drops.
This maintains survivability for branch wireless networks.
2
Determine the role of Sniffer mode versus SE-Connect mode.
Sniffer captures 802.11 layer 2 wireless frames for packet analyzer software, whereas SE-Connect captures layer 1 RF physical layer data for Cisco Spectrum Expert software.
Sniffer works at the frame/packet level while SE-Connect analyzes raw radio frequency interference.
3
Evaluate Rogue Detector mode operational behavior.
Rogue Detector APs do not serve client traffic on radios; instead, they monitor wired ARP/MAC tables to verify if rogue devices seen wirelessly are connected to the internal wired subnet.
Correlating wired MACs with wireless MACs isolates rogue APs physically connected to the enterprise network.

Anahtar Kavram

Cisco Access Point Operational Modes
Soru 1507Soru →

An active OSPFv2 Designated Router (DR) on a multiaccess Ethernet segment suddenly fails. Place the operational recovery events and DR/BDR re-election steps in the correct chronological order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct order of events following an OSPF DR failure is: (1) Neighbor routers detect DR loss via Dead Timer expiration, (2) The current BDR immediately promotes to DR, (3) Eligible routers initiate an election for the open BDR post, (4) The candidate with the highest interface priority or Router ID is elected new BDR, and (5) DROTHER routers complete FULL adjacency with the DR and new BDR while remaining in 2-WAY state with peer DROTHERs.
When an active DR fails, OSPF routers must first detect the loss when the Dead Router Timer expires. Upon detection, the active BDR is immediately promoted to DR without holding a new DR election. With the BDR position now vacant, remaining eligible routers (having priority > 0) participate in a BDR election, where the router with the highest interface priority (or highest Router ID if priorities are equal) wins. Finally, DROTHER routers form FULL adjacencies with both the DR and new BDR while maintaining 2-WAY state with non-DR/BDR peers.

Adım Adım Çözüm

1
Detect DR failure
Neighbors observe Dead Router Timer expiration.
OSPF routers on multiaccess networks wait until the Dead Timer expires without receiving Hello packets from the DR before taking action.
2
Promote active BDR
The existing BDR assumes the DR role.
OSPF avoids holding a fresh DR election; the pre-elected BDR instantly fills the DR position to ensure fast network convergence.
3
Trigger new BDR election
Eligible routers (priority > 0) initiate an election for the vacant BDR role.
Because the previous BDR was promoted to DR, the BDR position is empty and must be filled by a new election.
4
Determine election winner
The candidate with the highest interface priority (or highest Router ID) becomes the new BDR.
OSPF tie-breaking rules evaluate highest interface priority first, followed by highest Router ID.
5
Establish neighbor adjacencies
DROTHER routers transition to FULL state with the DR and new BDR while maintaining 2-WAY state with each other.
Multiaccess network design requires routers to form full adjacencies only with the DR and BDR to restrict link-state advertisement overhead.

Anahtar Kavram

OSPFv2 DR/BDR Non-Preemption and Failure Recovery Sequence
Tahmini Süre:2m 0s
Soru 1508Soru →

A network administrator is configuring Rapid PVST+ on a Cisco Catalyst switch. The administrator wants the switch to achieve a total Bridge Identifier (BID) priority of 1648416484 for VLAN 100100. Which Cisco IOS command correctly sets the base priority to accomplish this target total priority?

Cevabı ve açıklamayı göster

Cevap: spanning-tree vlan 100 priority 16384

Cevap

The command 'spanning-tree vlan 100 priority 16384' correctly sets the base bridge priority.
In Rapid PVST+, the total Bridge Identifier (BID) priority is the sum of the base bridge priority and the System ID Extension (which equals the VLAN ID). To achieve a total priority of 1648416484 in VLAN 100100, the base priority must be configured as 1638416384 (16384+100=1648416384 + 100 = 16484). Base priorities must be configured in multiples of 40964096.

Adım Adım Çözüm

1
Calculate the required base bridge priority
Base Priority = Total BID Priority - System ID Extension (VLAN ID) = 16484−100=1638416484 - 100 = 16384
Rapid PVST+ automatically appends the VLAN ID (System ID Extension) to the base bridge priority to form the final BID priority.
2
Verify priority increment rules
16384=4096×416384 = 4096 \times 4, which is a valid priority increment
Cisco IOS requires the base STP priority value to be configured in steps of 4096.
3
Formulate the correct Cisco IOS configuration syntax
spanning-tree vlan 100 priority 16384
The command syntax specifies the base priority without manually adding the VLAN ID.

Anahtar Kavram

Rapid PVST+ System ID Extension and Base Priority Increments
Soru 1509Soru →

An enterprise network features five routers participating in OSPFv2 on a shared Ethernet segment (192.168.12.0/24). A network engineer issues the command `show ip ospf neighbor` on router R3 and observes the following status output:

text
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 100 FULL/DR 00:00:35 192.168.12.1 GigabitEthernet0/0
10.10.10.2 50 FULL/BDR 00:00:38 192.168.12.2 GigabitEthernet0/0
10.10.10.4 0 FULL/DROTHER 00:00:31 192.168.12.4 GigabitEthernet0/0
10.10.10.5 200 FULL/DROTHER 00:00:36 192.168.12.5 GigabitEthernet0/0

If router 10.10.10.1 unexpectedly suffers an interface failure on GigabitEthernet0/0, which state transition will immediately occur on the segment?

Cevabı ve açıklamayı göster

Cevap: Router 10.10.10.2 is promoted to Designated Router (DR), and Router 10.10.10.5 is elected as the new Backup Designated Router (BDR).

Cevap

Router 10.10.10.2 is promoted to Designated Router (DR), and Router 10.10.10.5 is elected as the new Backup Designated Router (BDR).
In OSPF multiaccess networks, DR/BDR election follow two strict rules during failures: (1) When the DR goes down, the active BDR immediately assumes the DR role to maintain stability and prevent network re-convergence delays. (2) An election is subsequently conducted to fill the vacant BDR position. Since router 10.10.10.2 was the BDR, it becomes the DR. Among the remaining routers, router 10.10.10.5 has an interface priority of 200 (higher than remaining eligible routers), while router 10.10.10.4 has a priority of 0 (ineligible). Thus, router 10.10.10.5 is elected as the new BDR.

Adım Adım Çözüm

1
Analyze DR/BDR state transition upon DR failure
Router 10.10.10.2 (the current BDR) is automatically promoted to the Designated Router (DR) position.
OSPF DR/BDR election mechanics specify that whenever the current DR fails, the existing BDR takes over the DR role immediately without triggering a full DR election.
2
Evaluate eligibility for the newly vacant BDR position
Routers 10.10.10.4 (Priority 0) and 10.10.10.5 (Priority 200), alongside R3, are remaining neighbors.
Router 10.10.10.4 is configured with an interface priority of 0 (`ip ospf priority 0`), making it ineligible to become DR or BDR.
3
Determine the winner of the new BDR election
Router 10.10.10.5 wins the election and becomes the new BDR.
Among all eligible candidate routers for the vacant BDR role, Router 10.10.10.5 has the highest interface priority (200).

Anahtar Kavram

OSPFv2 DR/BDR Election Mechanics, Non-preemption, and Priority 0 Ineligibility
Soru 1510Soru →

A network administrator needs to create a static route on router R1 to reach remote subnet 2001:db8:100:50::/642001:\text{db8}:100:50::/64. The administrator decides to specify the next-hop router R2 using R2's link-local address fe80::20c:29ff:fe01:a1b2fe80::20c:29ff:fe01:a1b2 across R1's outbound GigabitEthernet 0/0/1 interface. Which Cisco IOS command correctly configures this IPv6 static route?

Cevabı ve açıklamayı göster

Cevap: ipv6 route 2001:db8:100:50::/64 GigabitEthernet0/0/1 fe80::20c:29ff:fe01:a1b2

Cevap

The command 'ipv6 route 2001:db8:100:50::/64 GigabitEthernet0/0/1 fe80::20c:29ff:fe01:a1b2' correctly configures the fully specified IPv6 static route.
The correct command uses the 'ipv6 route' keyword followed by the target destination network prefix (2001:db8:100:50::/642001:\text{db8}:100:50::/64), the local egress interface (GigabitEthernet0/0/1), and the link-local address of the adjacent router (fe80::20c:29ff:fe01:a1b2fe80::20c:29ff:fe01:a1b2). Because link-local addresses are valid only on their local segment, including the local exit interface is mandatory.

Adım Adım Çözüm

1
Identify the proper command prefix for IPv6 static routing.
The command must begin with 'ipv6 route'.
Cisco IOS separates IPv4 ('ip route') and IPv6 ('ipv6 route') static configuration commands.
2
Evaluate next-hop requirements when using link-local addresses.
Both the exit interface and the link-local next-hop IPv6 address must be specified.
Link-local addresses (fe80::/10) are local to a specific link. Without specifying the exit interface, the router cannot determine which physical segment the link-local address belongs to.
3
Verify command syntax order.
Syntax: 'ipv6 route <destination-prefix/prefix-length> <exit-interface> <link-local-address>'.
This fully specified static route syntax satisfies all Cisco IOS requirements for link-local next-hops.

Anahtar Kavram

IPv6 Fully Specified Static Routing with Link-Local Next-Hop
Soru 1511Soru →

In an enterprise WAN edge topology, router HQ-GW receives a path to subnet 10.80.0.0/1410.80.0.0/14 via a redistributed routing process resulting in an EIGRP External route (default Administrative Distance of 170170). An administrator needs to configure a floating static backup route for destination subnet 10.80.0.0/1410.80.0.0/14 using next-hop IP 192.168.200.1192.168.200.1 over an auxiliary link.

What minimum Administrative Distance integer value must be appended to the Cisco IOS command so that the static route remains dormant until the primary EIGRP External route fails?

Aşağıdaki boşlukları doldurun

ip route 10.80.0.0 255.240.0.0 192.168.200.1
Cevabı ve açıklamayı göster

Cevap

171
Cisco IOS routes are populated into the routing table based on Administrative Distance (AD), where lower values indicate higher trustworthiness. EIGRP External routes possess a default AD of 170. For a static route to act as a floating backup (remaining inactive until the primary path fails), its AD must be set higher than the primary path's AD. The minimum integer value greater than 170 is 171.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing source.
EIGRP External routes have a standard Cisco IOS default AD of 170.
Routing decisions in Cisco IOS select the path with the lowest Administrative Distance.
2
Determine the required Administrative Distance condition for a floating static route.
The floating static route's AD must be strictly greater than 170.
If the static route's AD were less than or equal to 170, it would either override the primary path or cause equal-cost multi-pathing/route instability rather than serving strictly as a backup.
3
Calculate the minimum integer AD required for the static route command.
170 + 1 = 171.
171 is the lowest whole integer value greater than the primary path's AD of 170.

Anahtar Kavram

Floating Static Route Administrative Distance Selection
Soru 1512Soru →

A network administrator needs to verify the operational summary of Network Address Translation (NAT) on a Cisco IOS router, including active translation totals, hit/miss counters, expired translations, and dynamic pool usage. Which Cisco IOS EXEC command displays these summary statistics?

Cevabı ve açıklamayı göster

Cevap: show ip nat statistics; show ip nat statistic

Cevap

The correct command is show ip nat statistics.
The show ip nat statistics command provides a summary view of NAT operations on a Cisco IOS router. It displays the total number of active translation entries, the count of inside and outside interfaces, memory allocation, pool configuration ranges, and hit/miss counters.

Adım Adım Çözüm

1
Identify the required NAT verification output
The requirement calls for operational summary metrics such as total active translations, hit/miss counts, and pool allocations rather than individual translation table entries.
Different EXEC commands serve distinct verification purposes in Cisco IOS.
2
Determine the appropriate Cisco IOS EXEC command
The command show ip nat statistics provides the summary metrics, interface designations, and pool configurations.
The show ip nat translations command lists active dynamic/static mappings, whereas show ip nat statistics summarizes overall NAT health and performance.

Anahtar Kavram

Cisco IOS NAT/PAT Verification Commands
Tahmini Süre:1m 0s
Soru 1513Soru →

An enterprise Cisco router receives an IPv4 packet destined for IP address 192.168.50.75. The router's routing table contains the following entries:

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

Gateway of last resort is not set

192.168.50.0/24 is variably subnetted, 4 subnets, 3 masks
O 192.168.50.0/24 [110/20] via 10.1.1.1, 00:14:22, GigabitEthernet0/0
S 192.168.50.0/25 [1/0] via 10.3.3.3
D 192.168.50.64/26 [90/30720] via 10.2.2.2, 00:08:15, GigabitEthernet0/1
C 192.168.50.64/28 is directly connected, GigabitEthernet0/2

Which forwarding path will the router select to forward this packet?

Cevabı ve açıklamayı göster

Cevap: Out GigabitEthernet0/2, because 192.168.50.64/28 provides the longest matching prefix for the destination IP address.

Cevap

The router will forward the packet out interface GigabitEthernet0/2 because the directly connected prefix 192.168.50.64/28 provides the longest prefix match (28 matching bits) for the destination IP 192.168.50.75.
When a router makes a packet forwarding decision, it checks all routes in the IPv4 routing table that encompass the destination IP address. The fundamental rule of IP routing is Longest Prefix Match (LPM): the route with the most specific prefix length (largest prefix number) is selected. Here, the target IP 192.168.50.75 falls into 192.168.50.64/28 (range .64 to .79). Because /28 is longer than /26, /25, and /24, the router forwards the packet directly out GigabitEthernet0/2.

Adım Adım Çözüm

1
Determine subnet ranges for all routing table entries
192.168.50.0/24 covers 192.168.50.0–192.168.50.255; 192.168.50.0/25 covers 192.168.50.0–192.168.50.127; 192.168.50.64/26 covers 192.168.50.64–192.168.50.127; 192.168.50.64/28 covers 192.168.50.64–192.168.50.79.
Identify which routes in the routing table actually match the destination IP address 192.168.50.75.
2
Check destination IP 192.168.50.75 against matching subnets
The destination address 192.168.50.75 matches all four listed routes in the routing table.
All four routes enclose the IP address 192.168.50.75 within their network address boundaries.
3
Apply the Longest Prefix Match (LPM) rule
Prefix lengths are /24, /25, /26, and /28. The /28 prefix has the greatest number of matching subnet mask bits.
Cisco IOS routing logic prioritizes the most specific prefix (longest netmask / highest prefix length) first before evaluating Administrative Distance or Metric.

Anahtar Kavram

Longest Prefix Match (LPM) Rule in Cisco IPv4 Routing
Soru 1514Soru →

An administrator issues the global configuration command `spanning-tree vlan 50 priority 28672` on a switch running Rapid PVST+. What total Bridge Priority value will be populated in the Bridge Identifier (BID) field of outgoing BPDUs for VLAN 50?

Cevabı ve açıklamayı göster

Cevap: 28722

Cevap

28722
Rapid PVST+ utilizes the IEEE 802.1t System ID Extension by default. The 16-bit priority portion of the Bridge Identifier (BID) is calculated by taking the configured 4-bit base priority (which must be a multiple of 4096) and adding the 12-bit VLAN ID (System ID Extension). Adding VLAN ID 50 to the configured base priority of 28672 produces a total Bridge Priority of 28722.

Adım Adım Çözüm

1
Identify the base priority configured for the VLAN
The configured base priority is 28672.
The command `spanning-tree vlan 50 priority 28672` sets the base bridge priority for VLAN 50.
2
Identify the System ID Extension value
The System ID Extension value is 50.
In Rapid PVST+, the System ID Extension field automatically carries the 12-bit VLAN ID.
3
Calculate the total Bridge Priority field in the Bridge Identifier (BID)
Total Bridge Priority = 28672 + 50 = 28722.
The 16-bit priority portion of the BID is composed of the 4-bit base priority multiplier plus the 12-bit System ID Extension.

Anahtar Kavram

Rapid PVST+ Bridge Identifier (BID) Structure and System ID Extension
Tahmini Süre:1m 0s
Soru 1515Soru →

An enterprise router with default settings maintains the following simplified IPv4 routing table excerpt:

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

O 10.12.0.0/16 [110/20] via 172.16.1.1, 00:15:30, GigabitEthernet0/0
S 10.12.32.0/20 [1/0] via 172.16.2.1, GigabitEthernet0/1
O 10.12.32.0/24 [110/50] via 172.16.3.1, 00:08:12, GigabitEthernet0/2
S 10.12.32.16/28 [200/0] via 172.16.4.1, GigabitEthernet0/3

The router receives an IP packet addressed to destination 10.12.32.2210.12.32.22. Which two statements correctly describe how the router processes and forwards this packet?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The router forwards the packet out GigabitEthernet0/3 toward next-hop 172.16.4.1 because the /28 route provides the longest prefix match.; The router evaluates prefix length before administrative distance, ignoring lower administrative distance values on broader subnets.

Cevap

The router forwards the packet out GigabitEthernet0/3 toward 172.16.4.1 using the longest prefix match (/28), and ignores lower administrative distance routes because prefix length comparison takes precedence over administrative distance.
When a router receives a packet, it searches its routing table for all matching prefixes and selects the route with the longest prefix match (most specific subnet mask). The destination address 10.12.32.22 matches four entries, but 10.12.32.16/28 has the longest prefix length (/28). Thus, the router forwards the packet via GigabitEthernet0/3. Administrative Distance is ignored when comparing different prefix lengths.

Adım Adım Çözüm

1
Determine which routing table entries match the destination IP address 10.12.32.22.
The destination address matches four routes: 10.12.0.0/16, 10.12.32.0/20, 10.12.32.0/24, and 10.12.32.16/28 (host range 10.12.32.17 - 10.12.32.30).
All four network blocks encompass the destination IP 10.12.32.22.
2
Apply the Longest Prefix Match (LPM) rule.
The /28 prefix length is the longest (most specific) match among /16, /20, /24, and /28.
The router forwarding decision logic strictly prioritizes the route with the most matching network bits (longest subnet mask).
3
Evaluate the impact of Administrative Distance and Metric.
Administrative Distance (200 vs 1 vs 110) is not compared across different prefix lengths; the /28 route is selected regardless of AD.
Administrative Distance is only used to select between multiple routes to the exact same prefix length.

Anahtar Kavram

Router Forwarding Decision Logic (Longest Prefix Match)
Soru 1516Soru →

Match each Cisco IPv4 routing table component to its correct functional description based on standard Cisco IOS routing operations.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Destination Prefix and Subnet Mask
Administrative Distance
Routing Metric
Next-Hop IP Address

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Destination Prefix and Subnet Mask matches 'Specifies the target network address range evaluated using longest prefix match logic.' Administrative Distance matches 'Defines the believability or trustworthiness rating of a route source when multiple protocols learn the same destination.' Routing Metric matches 'Represents the path cost or tie-breaker value calculated by a specific routing protocol to select the best path.' Next-Hop IP Address matches 'Indicates the IP address of the adjacent router interface to which traffic for the network should be forwarded.'
Each routing table component serves a distinct role in Cisco packet forwarding. The destination prefix identifies the destination subnet; administrative distance evaluates source trustworthiness across protocols; the metric determines path cost within the same protocol; and the next-hop address identifies the adjacent forwarding device.

Adım Adım Çözüm

1
Analyze the role of Destination Prefix and Subnet Mask
Identifies the network boundary used during prefix matching.
The subnet mask specifies how many bits represent the network portion of an IP address.
2
Analyze Administrative Distance (AD)
Identifies the administrative ranking between different protocol sources (e.g., OSPF AD 110 vs. EIGRP AD 90).
AD measures route source trustworthiness before routes enter the routing table.
3
Analyze Routing Metric
Identifies protocol-specific path evaluation metrics (e.g., bandwidth, delay, cost).
Metrics compare alternative paths provided by the same routing protocol.
4
Analyze Next-Hop IP Address
Identifies the adjacent forwarding device address.
Routers rewrite Layer 2 headers using the MAC address corresponding to the next-hop IP.

Anahtar Kavram

Routing Table Components and Interpretation
Soru 1517Soru →

Match each OSPFv2 network configuration or interface state on the left with its correct DR/BDR election behavior and timer trait on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Broadcast Network Type
Point-to-Point Network Type
Interface OSPF Priority set to 0

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Broadcast Network Type pairs with electing a DR/BDR using 10s/40s timers; Point-to-Point Network Type pairs with forming direct adjacencies without DR/BDR election using 10s/40s timers; Interface OSPF Priority set to 0 pairs with rendering the router interface completely ineligible for DR/BDR election.
Each OSPF network type has specific rules regarding DR/BDR elections and default timers. Broadcast networks elect DR/BDRs and use 10s/40s timers. Point-to-Point networks bypass DR/BDR elections entirely while sharing the 10s/40s timer defaults. Setting interface priority to 0 explicitly revokes DR/BDR eligibility.

Adım Adım Çözüm

1
Analyze OSPF Broadcast media characteristics.
Broadcast networks (like Ethernet) require DR and BDR election to reduce adjacencies on multiaccess segments, operating with 10s Hello and 40s Dead timers.
Broadcast multiaccess segments require a central Designated Router to handle LSA flooding.
2
Evaluate Point-to-Point OSPF network behavior.
Point-to-point links only connect two devices, so no DR/BDR election is needed, though 10s Hello and 40s Dead timers are still used.
DR/BDR election is unnecessary when only two routers share the link.
3
Determine the impact of setting OSPF interface priority to 0.
Setting the priority to 0 disqualifies the router interface from becoming DR or BDR.
Cisco IOS uses priority 0 specifically to keep lower-capacity routers in DROTHER state.

Anahtar Kavram

OSPFv2 Network Types and DR/BDR Selection Criteria
Soru 1518Soru →

An enterprise router is configured to perform dynamic NAT for an internal LAN subnet using a NAT pool containing a single public IP address (203.0.113.2203.0.113.2). Network users report that while the first host connecting to an external server successfully establishes a session, all subsequent internal hosts fail to reach external destinations simultaneously.

Review the following excerpt from the router's configuration:

text
interface GigabitEthernet0/0
ip address 10.50.0.1 255.255.255.0
ip nat inside
!
interface GigabitEthernet0/1
ip address 203.0.113.1 255.255.255.248
ip nat outside
!
ip access-list standard LAN_SERVERS
permit 10.50.0.0 0.0.255.255
!
ip nat pool PUBLIC_POOL 203.0.113.2 203.0.113.2 netmask 255.255.255.248
ip nat inside source list LAN_SERVERS pool PUBLIC_POOL

Which configuration change will resolve the issue and permit concurrent internet access for multiple internal hosts?

Cevabı ve açıklamayı göster

Cevap: Append the overload keyword to the ip nat inside source list LAN_SERVERS pool PUBLIC_POOL command.

Cevap

Append the overload keyword to the ip nat inside source list LAN_SERVERS pool PUBLIC_POOL command.
Appending the 'overload' keyword to the dynamic NAT statement transforms the mapping from dynamic 1-to-1 NAT into Port Address Translation (PAT). PAT multiplexes multiple internal IP addresses onto a single public inside global address by varying the layer 4 source port numbers, thereby permitting concurrent sessions for all LAN hosts.

Adım Adım Çözüm

1
Analyze the configuration and symptoms.
The statement 'ip nat inside source list LAN_SERVERS pool PUBLIC_POOL' lacks the 'overload' keyword, which instructs Cisco IOS to perform dynamic 1-to-1 NAT rather than 1-to-many PAT.
Dynamic 1-to-1 NAT allocates one public IP address from the pool per host. Because the pool contains only one IP address (203.0.113.2), only one device can be translated at any given time.
2
Identify the required NAT operational mode for single IP multi-host sharing.
Port Address Translation (PAT / NAT Overload) allows thousands of concurrent flows to share one public IP address by assigning unique source port numbers.
Adding the 'overload' keyword at the end of a dynamic NAT mapping command explicitly enables PAT.
3
Formulate the correct Cisco IOS CLI command modification.
Execute 'ip nat inside source list LAN_SERVERS pool PUBLIC_POOL overload' in global configuration mode.
This resolves port translation allocation and permits all internal hosts matching ACL LAN_SERVERS to reach external networks concurrently.

Anahtar Kavram

Inside Source NAT and PAT (Overload) Pool Configuration
Tahmini Süre:2m 0s
Soru 1519Soru →

A network administrator is configuring IPv4 static routes on a Cisco router to connect a branch site. Which two statements accurately describe the operational characteristics of static routing syntax and forwarding decisions on Cisco routers? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Specifying a next-hop IPv4 address requires the router to perform a recursive lookup to determine the egress interface.; Specifying an exit interface directly on a point-to-point link allows the router to forward traffic without a recursive lookup.

Cevap

The statement explaining that specifying a next-hop IPv4 address requires a recursive lookup, and the statement explaining that specifying an exit interface on a point-to-point link avoids a recursive lookup.
The correct statements reflect standard Cisco IOS forwarding logic: specifying a next-hop IP address forces a recursive routing table lookup to identify the egress interface, whereas specifying a directly connected exit interface on a point-to-point link allows immediate interface mapping without recursive lookup.

Adım Adım Çözüm

1
Analyze static route next-hop lookup behavior.
When a static route uses a next-hop IPv4 address, the router must search its routing table a second time (recursive lookup) to find which outgoing interface reaches that next-hop address.
Next-hop resolution determines physical layer 2 and egress interface mapping.
2
Analyze static route exit interface lookup behavior on point-to-point links.
When an exit interface is specified directly on a point-to-point connection, the router immediately knows which physical interface to forward the packet out of.
Directly connected point-to-point links do not require recursive next-hop IP resolution.

Anahtar Kavram

IPv4 Static Route Forwarding & Syntax Characteristics
Tahmini Süre:1m 0s
Soru 1520Soru →

Four Cisco routers (HQ-R1, HQ-R2, HQ-R3, and HQ-R4) are connected to a shared GigabitEthernet switch on the broadcast multiaccess network 10.200.1.0/2410.200.1.0/24. All routers are powered on simultaneously with default OSPFv2 settings except for interface priority values. The interfaces are configured as follows:

- HQ-R1: `ip ospf priority 0`, Loopback0: 192.168.100.1/32192.168.100.1/32, Gi0/0: 10.200.1.1/2410.200.1.1/24
- HQ-R2: `ip ospf priority 10`, Loopback0: 10.10.10.10/3210.10.10.10/32, Gi0/0: 10.200.1.2/2410.200.1.2/24
- HQ-R3: `ip ospf priority 20`, Loopback0: 1.1.1.1/321.1.1.1/32, Gi0/0: 10.200.1.3/2410.200.1.3/24
- HQ-R4: `ip ospf priority 20`, Loopback0: 2.2.2.2/322.2.2.2/32, Gi0/0: 10.200.1.4/2410.200.1.4/24

Which router role assignment correctly describes the outcome of the DR/BDR election on this Ethernet segment?

Cevabı ve açıklamayı göster

Cevap: HQ-R4 is elected as DR, and HQ-R3 is elected as BDR.

Cevap

HQ-R4 is elected as DR, and HQ-R3 is elected as BDR.
In OSPF DR/BDR elections on broadcast multiaccess networks, routers first evaluate interface priority values. An interface priority of 0 immediately excludes a router (HQ-R1) from election eligibility. Between HQ-R3 and HQ-R4, both share the highest priority (20). The tie is broken by comparing their Router IDs (derived from active loopback interfaces). Because 2.2.2.22.2.2.2 is greater than 1.1.1.11.1.1.1, HQ-R4 wins the DR election, and HQ-R3 becomes the BDR.

Adım Adım Çözüm

1
Evaluate interface priority eligibility
HQ-R1 has an OSPF priority of 0 and is immediately excluded from becoming DR or BDR, despite having the highest loopback IP address (192.168.100.1192.168.100.1).
An OSPF priority of 0 explicitly configured on an interface renders the router ineligible for DR/BDR election.
2
Compare interface priorities among remaining routers
HQ-R3 and HQ-R4 both have an interface priority of 20, which is strictly higher than HQ-R2's priority of 10.
OSPF DR/BDR election primary criterion is highest interface priority.
3
Break priority tie using Router ID
HQ-R3 has Router ID 1.1.1.11.1.1.1 (from Loopback0) and HQ-R4 has Router ID 2.2.2.22.2.2.2 (from Loopback0). Since 2.2.2.2>1.1.1.12.2.2.2 > 1.1.1.1, HQ-R4 is elected DR, and HQ-R3 is elected BDR.
When interface priorities tie, the highest OSPF Router ID breaks the tie.

Anahtar Kavram

OSPFv2 DR/BDR election precedence (Priority > Router ID) and Priority 0 exclusion
Tahmini Süre:2m 0s
ÖncekiSayfa 76 / 100Sonraki
Tüm alıştırma soruları — Cisco CCNA | Examkin