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Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 1621Soru →

An enterprise router is configured for dynamic Network Address Translation (NAT) using an IP pool containing four public IP addresses (198.51.100.1198.51.100.1 to 198.51.100.4198.51.100.4). Internal users report that only four devices can access external resources at any given time, and subsequent connection attempts by other hosts fail until an existing session terminates. Which configuration change will allow all internal hosts to share the public IP address pool simultaneously?

Cevabı ve açıklamayı göster

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

Cevap

Append the overload keyword to the ip nat inside source list pool command.
The correct response specifies appending the overload keyword to the dynamic NAT configuration statement (e.g., ip nat inside source list 1 pool NAT_POOL overload). This enables Port Address Translation (PAT), allowing multiple internal devices to share the public addresses by tracking unique source port numbers.

Adım Adım Çözüm

1
Analyze the reported issue
Dynamic NAT without PAT provides strict 1-to-1 translations, restricting concurrent internet access to the exact number of public IP addresses in the pool (4 hosts).
Omitting port-level translation causes the router to exhaust available public addresses after 4 active sessions.
2
Identify the required Cisco IOS command enhancement
Appending the 'overload' keyword converts dynamic NAT to Port Address Translation (PAT).
PAT tracks source TCP/UDP port numbers, enabling thousands of inside private hosts to multiplex over the same pool of public IP addresses.

Anahtar Kavram

Port Address Translation (PAT) Overload Configuration
Tahmini Süre:1m 15s
Soru 1622Soru →

An administrator notices that while the first host on the internal network (10.1.10.0/2410.1.10.0/24) can access the internet, subsequent hosts are unable to establish outbound connections simultaneously. Inspecting Router1 reveals the following running configuration:

text
access-list 105 permit ip 10.1.10.0 0.0.0.255 any
ip nat pool EDGE_POOL 203.0.113.5 203.0.113.5 prefix-length 32
ip nat inside source list 105 pool EDGE_POOL

Command output from `show ip nat statistics` confirms:
text
Total active translations: 1 (0 static, 1 dynamic, 0 extended)
Outside interfaces: GigabitEthernet0/1
Inside interfaces: GigabitEthernet0/0
Hits: 142 Misses: 18
Dynamic mappings:
-- Inside Source
access-list 105 pool EDGE_POOL ref count 1

Which configuration modification must be applied to Router1 to allow all internal hosts on the 10.1.10.0/2410.1.10.0/24 network to share the single IP address assigned to `EDGE_POOL` concurrently?

Cevabı ve açıklamayı göster

Cevap: Append the overload keyword to the statement: ip nat inside source list 105 pool EDGE_POOL overload

Cevap

Appending the overload keyword to the inside source NAT configuration command (ip nat inside source list 105 pool EDGE_POOL overload) enables Port Address Translation (PAT).
The configuration present on Router1 establishes standard dynamic 1-to-1 NAT. Because the pool contains only one IP address (203.0.113.5), only the first internal host receives a translation. Appending the overload keyword modifies the translation engine to perform Port Address Translation (PAT), allowing multiple inside local hosts to share a single inside global address by using unique transport-layer port numbers.

Adım Adım Çözüm

1
Analyze the configuration and verification output
The command 'ip nat inside source list 105 pool EDGE_POOL' without the overload keyword configures standard dynamic NAT. Because EDGE_POOL contains only a single IP address (203.0.113.5), only 1 dynamic translation entry (extended = 0) can exist at any given time.
Standard dynamic NAT allocates global IP addresses on a one-to-one basis. Once all pool addresses are exhausted, additional hosts attempting connection are dropped (misses increase).
2
Identify the missing component for port multiplexing
To allow multiple internal hosts to share one global IP address, Layer 4 port numbers must be tracked using Port Address Translation (PAT).
PAT requires the 'overload' keyword at the end of the 'ip nat inside source' command.
3
Formulate the correct configuration command
Execute 'ip nat inside source list 105 pool EDGE_POOL overload' on Router1.
This enables extended translations, allowing thousands of concurrent internal sockets to multiplex over port numbers assigned to 203.0.113.5.

Anahtar Kavram

Port Address Translation (PAT) Overload Keyword Requirement
Tahmini Süre:2m 0s
Soru 1623Soru →

A network engineer is managing a broadcast multiaccess Ethernet segment with four routers running OSPFv2 in Area 0. The output below is taken from router R2:

text
R2# show ip ospf interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 192.168.10.2/24, Area 0
Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 1
State DROTHER, Priority 0
Designated Router (ID) 4.4.4.4, Interface address 192.168.10.4
Backup Designated Router (ID) 3.3.3.3, Interface address 192.168.10.3

The engineer executes the command `ip ospf priority 250` on R2's GigabitEthernet0/0 interface. Shortly after, the current Designated Router (R4) reboots. Assuming all other routers maintain their default priority of 1 and no OSPF processes are cleared manually, which role will router R2 assume on the segment after convergence?

Cevabı ve açıklamayı göster

Cevap: Backup Designated Router (BDR)

Cevap

Backup Designated Router (BDR)
In OSPFv2 broadcast networks, elections are non-preemptive. When the active DR (R4) fails or reboots, the existing BDR (R3) is automatically promoted to DR. A new election is then held specifically to fill the now-vacant BDR role. Since R2's interface priority was increased from 0 to 250, R2 is eligible and wins the BDR election over any remaining routers with default priority 1. Therefore, R2 becomes the Backup Designated Router (BDR).

Adım Adım Çözüm

1
Analyze initial OSPF roles and interface priority configuration
R4 is DR (Router ID 4.4.4.4), R3 is BDR (Router ID 3.3.3.3), and R2 is DROTHER because its priority was 0.
An OSPF priority of 0 excludes a router interface from participating in DR/BDR elections.
2
Evaluate the impact of changing interface priority to 250 on R2
R2 becomes eligible to participate in future DR/BDR elections with a priority of 250, but elections are non-preemptive while active DR/BDR roles are filled.
OSPF DR/BDR elections do not preempt active role holders upon configuration changes.
3
Determine role transitions following the failure/reboot of the DR (R4)
R3 (the active BDR) is immediately promoted to DR. A new election takes place to fill the vacant BDR position.
OSPF rules state that when a DR fails, the active BDR automatically becomes the new DR.
4
Select the winner of the new BDR election
R2 wins the election for BDR because its priority (250) is higher than the remaining candidate routers (priority 1).
The router with the highest non-zero priority wins the BDR election.

Anahtar Kavram

OSPF DR/BDR Election Non-Preemption and Promotion Rules
Tahmini Süre:1m 30s
Soru 1624Soru →

A network administrator is configuring HSRP on a router's GigabitEthernet0/0 interface, which has been assigned the physical IPv4 address 192.168.10.1/24192.168.10.1/24. The administrator enters the command `standby 1 ip 192.168.10.1` under the interface configuration mode. What issue does this configuration introduce?

Cevabı ve açıklamayı göster

Cevap: It configures the HSRP virtual IP address to match a physical interface IP address, which is invalid in HSRP.

Cevap

Assigning the physical interface IPv4 address as the HSRP virtual IP address is an invalid configuration because HSRP requires the virtual IP to be a separate, distinct IP address within the subnet.
In Cisco Hot Standby Router Protocol (HSRP), the virtual IP address shared by the group must be a unique IP address on the local subnet that is not assigned to any router's physical interface. Attempting to assign a router's physical IP address as the HSRP virtual IP address is invalid and prevents proper operation.

Adım Adım Çözüm

1
Identify the IP address assigned to the physical interface and the IP address specified in the `standby` command.
The physical interface IP address is 192.168.10.1192.168.10.1, and the command sets the virtual IP to 192.168.10.1192.168.10.1.
Comparing these addresses verifies whether the virtual IP collides with a physical IP.
2
Recall HSRP rules regarding virtual IP address assignment.
Unlike VRRP (which allows owning the IP address), HSRP requires the virtual IP address to be an unused IP address on the subnet, distinct from all router physical interface IPs in the group.
Enforces proper HSRP protocol behavior and prevents address duplicate conflicts.

Anahtar Kavram

HSRP Virtual IP Address Assignment Rules
Soru 1625Soru →

An administrator is verifying Network Time Protocol (NTP) operations on a Cisco IOS router. Which of the following statements regarding NTP functionality and status are correct? (Select TWO.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The command `ntp master 4` configures the router to act as an NTP server serving time at stratum 4.; A stratum value of 16 indicates that the local device clock is unsynchronized and considered invalid.

Cevap

The command `ntp master 4` configures the router as an NTP server at stratum 4, and a stratum level of 16 indicates an unsynchronized clock state.
Configuring `ntp master 4` causes the router to act as an authoritative NTP clock source at stratum 4. Furthermore, stratum 16 is the standard NTP representation for an unsynchronized device or an unreachable clock source.

Adım Adım Çözüm

1
Analyze NTP stratum range and master configuration commands.
The `ntp master [number]` command allows an IOS router to advertise itself as an NTP master at the specified stratum. Valid synchronized strata are 1 through 15.
Stratum 1 is directly attached to a reference clock (like GPS/atomic), and each hop increments the stratum by 1. Stratum 16 defines an unsynchronized state.
2
Evaluate transport layer protocols used by NTP.
NTP uses UDP port 123.
UDP is chosen over TCP to minimize latency and synchronization overhead.

Anahtar Kavram

NTP Stratum Hierarchy and Master Configuration
Tahmini Süre:45s
Soru 1626Soru →

An edge router receives the primary route to remote destination network 10.10.0.0/1610.10.0.0/16 via external BGP (eBGP) from ISP-1 using default settings. The network administrator attempts to configure a floating static backup route toward ISP-2 using the command `ip route 10.10.0.0 255.255.0.0 192.168.1.2 15`. Which behavior will be observed on the router regarding this destination?

Cevabı ve açıklamayı göster

Cevap: The static route immediately replaces the eBGP route as the primary active route in the routing table because its Administrative Distance of 15 is lower than the default eBGP Administrative Distance of 20.

Cevap

The static route immediately replaces the eBGP route as the primary active route in the routing table because its Administrative Distance of 15 is lower than the default eBGP Administrative Distance of 20.
In Cisco IOS, lower Administrative Distance values take precedence. The default Administrative Distance for external BGP (eBGP) is 20. Because the static route was configured with an explicit Administrative Distance of 15, the router considers it more reliable than the eBGP route. As a result, the static route becomes the primary active path in the routing table rather than remaining an inactive backup.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing protocol.
The primary route is learned via external BGP (eBGP), which has a default Cisco IOS Administrative Distance of 2020.
Administrative Distance indicates the trustworthiness of a routing source.
2
Analyze the configured Administrative Distance of the static route.
The trailing argument in `ip route 10.10.0.0 255.255.0.0 192.168.1.2 15` specifies an Administrative Distance of 1515.
The optional metric value at the end of the `ip route` syntax overrides the default static route AD of 1.
3
Compare the AD values to determine routing table selection.
Since 15<2015 < 20, the static route is considered more believable than the eBGP route.
Routers select the route with the lowest Administrative Distance when multiple sources advertise the exact same prefix length.

Anahtar Kavram

Floating Static Route Administrative Distance Precedence
Soru 1627Soru →

Router R3 is configured with the following interfaces and IP address states:

- Loopback0: 10.255.255.1/32 (Status: up, Line Protocol: up)
- Loopback1: 172.16.100.1/32 (Status: administratively down, Line Protocol: down)
- GigabitEthernet0/0: 192.168.1.1/24 (Status: up, Line Protocol: up)

OSPFv2 process 1 is initialized on R3 without a manually configured router ID. Later, a network engineer enters the following commands:

R3(config)# router ospf 1
R3(config-router)# router-id 1.1.1.1

No additional commands are executed and the OSPF process is not reset. What IPv4 address is currently active as the OSPF router ID for process 1?

Cevabı ve açıklamayı göster

Cevap: 10.255.255.1

Cevap

10.255.255.1
Upon initial process startup, OSPF selects 10.255.255.1 because active loopback interfaces take priority over physical interfaces, and Loopback0 is the only active loopback (Loopback1 is administratively down). When the 'router-id 1.1.1.1' command is subsequently entered under the OSPF process, Cisco IOS requires the process to be reset (e.g., via 'clear ip ospf process') before the change becomes active. Since no reset occurred, 10.255.255.1 remains the active OSPF router ID.

Adım Adım Çözüm

1
Determine initial OSPF Router ID election upon process initialization
10.255.255.1 is chosen as the active router ID
When OSPF process 1 starts without a manual router-id command, it selects the highest IPv4 address among active (up/up) loopback interfaces. Loopback0 (10.255.255.1) is active, while Loopback1 is administratively down and ignored. Physical interfaces like GigabitEthernet0/0 are ignored because an active loopback interface exists.
2
Evaluate the impact of configuring 'router-id 1.1.1.1' on a running OSPF process
The new router ID 1.1.1.1 is queued but does not take immediate effect
OSPF Router ID selection in Cisco IOS is non-preemptive. Changing the router ID under the OSPF process does not dynamically update the active router ID for an already running process.
3
Check if any process reload or reset command was executed
No reset occurred; the original router ID remains active
A process restart (such as executing 'clear ip ospf process') or device reload is required to apply the newly configured router ID. Because no reset was performed, 10.255.255.1 remains the active router ID.

Anahtar Kavram

OSPFv2 Router ID Election Precedence and Non-Preemptive Re-election
Tahmini Süre:2m 0s
Soru 1628Soru →

An engineer inspects the operational status of an active OSPFv2 broadcast network using the following Cisco IOS CLI output from router HQ-R1:

text
HQ-R1# show ip ospf interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 1.1.1.1, Interface address 10.10.10.1
Backup Designated router (ID) 2.2.2.2, Interface address 10.10.2.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:03
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 2.2.2.2 (Backup Designated Router)

A third router, HQ-R3 (Router ID 3.3.3.3), is subsequently connected to the same Ethernet switch segment with its OSPF interface priority configured as 255. If all existing routers remain powered on with active OSPF processes, which statement correctly describes the OSPF role assignment for HQ-R3 once neighbor adjacencies settle?

Cevabı ve açıklamayı göster

Cevap: HQ-R3 operates as a DROTHER because active DR and BDR roles in OSPFv2 are non-preemptive.

Cevap

HQ-R3 becomes a DROTHER because OSPFv2 DR and BDR elections are non-preemptive once operational roles are established on a multiaccess network segment.
In OSPFv2 broadcast multiaccess networks, DR and BDR elections are non-preemptive. Once a DR and BDR are elected and active, adding a new router with a higher interface priority (such as 255) will not trigger a role change. The new router assumes the DROTHER role until the DR or BDR router fails, disconnects, or has its OSPF process reset.

Adım Adım Çözüm

1
Analyze the existing OSPFv2 segment state from the CLI output.
HQ-R1 (1.1.1.1) is actively serving as the Designated Router (DR) and HQ-R2 (2.2.2.2) is serving as the Backup Designated Router (BDR).
The election process has already taken place and active DR/BDR roles are currently filled.
2
Evaluate the impact of introducing HQ-R3 with interface priority 255 onto the broadcast network.
HQ-R3 establishes adjacency but does not trigger a re-election for DR or BDR.
OSPFv2 DR/BDR elections are strictly non-preemptive. A newly attached router will not displace an active DR or BDR regardless of priority or Router ID.
3
Determine the final OSPF state of HQ-R3.
HQ-R3 transitions to the DROTHER state on the multiaccess link.
Because both DR and BDR roles are already filled, HQ-R3 functions as a 2-WAY / FULL neighbor (DROTHER) with non-DR/BDR routers.

Anahtar Kavram

OSPFv2 Non-Preemptive DR/BDR Election Rule
Soru 1629Soru →

Match each Cisco IOS IPv4 routing table entry component to its correct functional definition or metric descriptor.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Administrative Distance (AD)
Routing Metric
Next-Hop Address
Prefix Length

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Administrative Distance matches the measure of route source trustworthiness; Routing Metric matches the path cost calculated by a specific protocol; Next-Hop Address matches the IPv4 address of the adjacent router interface; Prefix Length matches the subnet mask specifier in CIDR notation used for longest prefix match.
Each entry component in a Cisco IOS routing table plays a distinct role: Administrative Distance measures source believability (0-255), Routing Metric determines the best path within a specific routing protocol, the Next-Hop Address defines the adjacent router's interface IP for forwarding, and the Prefix Length dictates how many bits match the destination address during lookup.

Adım Adım Çözüm

1
Analyze Administrative Distance (AD)
AD evaluates protocol trustworthiness (e.g., lower AD is preferred when different protocols report the same prefix).
It allows Cisco IOS to prioritize route sources.
2
Analyze Routing Metric
Metric measures path desirability within a single routing protocol.
It acts as a tie-breaker when multiple paths exist within the same protocol.
3
Analyze Next-Hop Address
Next-hop represents the forwarding neighbor's IP interface.
It tells the router where to transmit layer 3 packets.
4
Analyze Prefix Length
Prefix length defines the network mask.
It is used by the forwarding engine during longest prefix matching.

Anahtar Kavram

Interpretation of Routing Table Components and Attributes
Soru 1630Soru →

A network administrator is inspecting a Cisco Catalyst switch port connected to a desktop computer assigned to VLAN 50. Output from the `show interfaces gigabitEthernet 1/0/12 switchport` command reveals that the interface is operating under default settings with an administrative mode of `dynamic auto` and an access VLAN of 1. Which configuration commands must be entered in interface configuration mode to assign this port to VLAN 50 as a dedicated static access port?

Cevabı ve açıklamayı göster

Cevap: switchport mode access
switchport access vlan 50

Cevap

The commands 'switchport mode access' followed by 'switchport access vlan 50' correctly assign the interface to VLAN 50 as a static access port.
To properly configure an end-user device port in Cisco IOS, administrators should explicitly define the switchport mode as access using 'switchport mode access' and then assign the access VLAN with 'switchport access vlan 50'. This prevents unwanted DTP negotiation and ensures the interface remains a dedicated access port.

Adım Adım Çözüm

1
Set the administrative mode to static access.
Disables Dynamic Trunking Protocol (DTP) negotiation on the interface.
By default, Cisco Catalyst interfaces are configured as dynamic auto or dynamic desirable. Using 'switchport mode access' forces the port to act strictly as a Layer 2 access port.
2
Assign the access port to the target VLAN.
Places untagged traffic entering GigabitEthernet1/0/12 into VLAN 50.
The command 'switchport access vlan 50' associates untagged frames received on this interface with VLAN 50.

Anahtar Kavram

Configuring Cisco IOS L2 access ports and overriding DTP dynamic modes
Tahmini Süre:1m 0s
Soru 1631Soru →

A network engineer is allocated the IPv4 address block 172.30.128.0/20172.30.128.0/20 for an enterprise campus expansion project. The engineer needs to divide this block into smaller, equal-sized subnetworks using a prefix mask of /25/25. What is the total number of subnets that can be created from this original /20/20 block?

Cevabı ve açıklamayı göster

Cevap: 32

Cevap

The total number of subnets that can be created is 32.
Moving from a /20/20 prefix to a /25/25 prefix borrows 5 host bits (25−20=525 - 20 = 5). Calculating 252^5 gives 32 distinct subnets.

Adım Adım Çözüm

1
Calculate the number of borrowed subnet bits
5 bits borrowed (25−20=525 - 20 = 5)
The difference between the target prefix length and the starting prefix length represents the network bits borrowed from the host portion.
2
Calculate the total subnet count
32 subnets (25=322^5 = 32)
Each borrowed bit doubles the number of created subnets (2n2^n, where nn is the number of borrowed bits).

Anahtar Kavram

Subnet counting using CIDR prefix borrowing
Soru 1632Soru →

A network engineer wants to configure managed switches to alert the SNMP management station upon link status changes. To prevent missed alerts due to unacknowledged packet delivery, the engineer requires a message type that mandates an explicit confirmation receipt back from the manager. Which SNMP message type should be configured on the switches?

Cevabı ve açıklamayı göster

Cevap: SNMP InformRequest

Cevap

SNMP InformRequest (or Inform) is the correct message type because it requires an explicit acknowledgement receipt from the receiving SNMP manager.
SNMP InformRequest messages are specifically designed to provide reliable notification handling. Unlike standard Traps, when an agent sends an Inform, the receiver must reply with an acknowledgement; if no confirmation is received, the agent can retransmit the alert.

Adım Adım Çözüm

1
Identify the operational requirement in the scenario.
The requirement is an event alert notification originating from network switches that provides reliable delivery through mandatory receiver acknowledgement.
Event-driven notifications initiated by managed devices are either Traps or Informs.
2
Compare SNMP Trap and SNMP InformRequest operational mechanics.
Traps are unacknowledged (fire-and-forget), whereas Informs require the manager to send an SNMP response acknowledging receipt.
If an Inform message is not acknowledged by the NMS within a timeout period, the sending device can retransmit the notification.

Anahtar Kavram

SNMP Traps vs SNMP Informs Reliability Mechanics
Soru 1633Soru →

A network engineer is configuring a new Cisco IOS router (R1) to synchronize its system time with a primary enterprise NTP server operating at Stratum 2. R1 is also expected to act as an NTP server for downstream switches once synchronized. Arrange the operational steps in the exact chronological sequence in which R1 processes NTP synchronization from initial CLI configuration to serving downstream clients.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence starts with entering the NTP server configuration command, followed by sending UDP port 123 query packets, receiving the Stratum 2 response, calculating the local Stratum 3 value, and finally transitioning to synchronized state while serving downstream clients.
The operational sequence moves logically from CLI command execution, outward network request over UDP 123, inbound response processing, mathematical stratum calculation (2+1=32 + 1 = 3), to local state synchronization and downstream service activation.

Adım Adım Çözüm

1
Identify the initial configuration trigger
Execution of 'ntp server 10.10.10.1' initializes the local NTP daemon polling timer.
NTP operations cannot begin until a server association is defined in configuration.
2
Determine initial packet transmission details
R1 sends outgoing NTP client polling messages using UDP port 123.
NTP uses UDP port 123 for all client/server communications.
3
Process server response details
R1 receives packet payload containing Stratum 2 marker from 10.10.10.1.
The upstream server reports its own stratum distance from reference clock (Stratum 2).
4
Perform Stratum level mathematical calculation
Local stratum is evaluated as Server Stratum+1=2+1=3\text{Server Stratum} + 1 = 2 + 1 = 3.
Every network hop down the NTP hierarchy increments the Stratum level by exactly 1.
5
Establish synchronized state and downstream server role
System clock updates to synchronized state, enabling R1 to answer downstream queries at Stratum 3.
A Cisco router will not serve authoritative time to downstream clients until its own clock is synchronized to an upstream source.

Anahtar Kavram

NTP Client-Server Synchronization Workflow and Stratum Calculation
Tahmini Süre:2m 0s
Soru 1634Soru →

Which of the following statements correctly compare the default operational characteristics and parameters of HSRP (v1) and VRRP (v2)? (Select two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: HSRPv1 uses virtual MAC addresses in the format 0000.0c07.acXX, whereas VRRPv2 uses the format 0000.5e00.01XX.; HSRP names the primary forwarding gateway the Active router, whereas VRRP names it the Master router.

Cevap

The correct statements are that HSRPv1 uses virtual MAC addresses formatted as 0000.0c07.acXX while VRRPv2 uses 0000.5e00.01XX, and HSRP designates the forwarding router as Active while VRRP designates it as Master.
HSRPv1 and VRRPv2 differ in virtual MAC schemes (0000.0c07.acXX vs 0000.5e00.01XX) and role naming conventions (Active/Standby in HSRP vs Master/Backup in VRRP).

Adım Adım Çözüm

1
Analyze virtual MAC address structure for both protocols
HSRPv1 uses standard MAC prefix 0000.0c07.ac followed by the group ID. VRRPv2 uses 0000.5e00.01 followed by the group ID.
Each protocol reserves a specific IEEE OID/MAC range for virtual gateway identification.
2
Compare role terminology between Cisco proprietary HSRP and open standard VRRP
HSRP uses Active/Standby roles, whereas VRRP uses Master/Backup roles.
Standardization differences lead to distinct terminology for equivalent primary/secondary forwarding roles.
3
Evaluate IP address assignment and preemption rules
VRRP supports using an interface's physical IP as the virtual IP address and enables preemption by default. HSRP requires a separate virtual IP address and disables preemption by default.
Differentiates implementation behavior between the two First Hop Redundancy Protocols.

Anahtar Kavram

HSRP and VRRP Operational Differences
Soru 1635Soru →

An enterprise router R1 is configured as the active HSRPv1 router for Group 10 with an initial priority of 110 and preemption enabled. R1 tracks its WAN uplink interface GigabitEthernet0/1 with a priority decrement value of 20. Router R2 is configured as the standby router for Group 10 with a priority of 100 and preemption enabled. Place the operational events in the exact chronological sequence following a line-protocol failure on R1's GigabitEthernet0/1 interface until failover convergence completes.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct chronological sequence is: (1) R1 detects tracked interface failure -> (2) R1 decrements priority to 90 -> (3) R1 sends Hello with priority 90 -> (4) R2 compares priorities (100 vs 90) -> (5) R2 transmits an HSRP Coup message -> (6) R2 enters Active state and issues a Gratuitous ARP while R1 becomes Standby.
HSRP convergence follows a strict sequence when interface tracking degrades priority: detection of interface failure occurs first, leading to immediate priority calculation on the active router. The reduced priority is then advertised to the standby router via standard Hello messages. The standby router evaluates the lower priority, triggers preemption by sending a Coup message, assumes the Active state, and finally sends a Gratuitous ARP to re-align Layer 2 switch forwarding tables.

Adım Adım Çözüm

1
Detect Link Failure
R1 detects line-protocol failure on GigabitEthernet0/1.
Interface tracking monitors the operational state of the configured interface.
2
Calculate Priority Decrement
R1's priority changes from 110 to 90.
The configured track action automatically subtracts 20 from R1's active priority (110−20=90110 - 20 = 90).
3
Advertise New Priority
R1 sends an HSRP Hello packet containing priority 90.
HSRP routers communicate state changes via periodic Hello messages sent to 224.0.0.2.
4
Evaluate Preemption Criteria
R2 identifies that its priority (100) exceeds R1's reported priority (90).
With preemption configured, a standby router constantly compares received active priority against its own.
5
Signal Takeover
R2 sends an HSRP Coup message.
The Coup message informs the current active router that a higher-priority router is asserting control.
6
Final Convergence & Traffic Steering
R2 transitions to Active, issues a Gratuitous ARP for the virtual IP/MAC, and R1 steps down to Standby.
The Gratuitous ARP updates Layer 2 switch forwarding tables so host traffic is immediately steered to R2.

Anahtar Kavram

HSRP Interface Tracking and Preemption Mechanism
Soru 1636Soru →

A network administrator is implementing Port Address Translation (PAT) on a Cisco IOS router to allow hosts on the internal subnet 10.45.10.0/2410.45.10.0/24 to access the Internet. The WAN interface GigabitEthernet0/0/1 receives its dynamic IP address from the ISP, while interface GigabitEthernet0/0/0 connects to the internal LAN. Which two configuration steps or commands are required to successfully enable PAT using the WAN interface address? (Select TWO options.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Specify the translation mapping using the command ip nat inside source list 1 interface GigabitEthernet0/0/1 overload; Identify NAT roles on the router interfaces by configuring ip nat inside on GigabitEthernet0/0/0 and ip nat outside on GigabitEthernet0/0/1

Cevap

Port Address Translation (PAT) using a router interface requires defining the internal and external NAT interface designations (ip nat inside / ip nat outside) and creating the NAT statement referencing the matching ACL and interface with the overload keyword (ip nat inside source list 1 interface GigabitEthernet0/0/1 overload).
To successfully establish Port Address Translation (PAT) using an interface address, two mandatory requirements must be fulfilled: defining the NAT boundary interface roles (ip nat inside on the LAN side and ip nat outside on the WAN side) and writing the translation command linking the matching ACL to the WAN interface with the overload keyword present.

Adım Adım Çözüm

1
Designate the internal and external NAT interfaces.
GigabitEthernet0/0/0 is configured with ip nat inside and GigabitEthernet0/0/1 is configured with ip nat outside.
Cisco IOS NAT needs to identify ingress and egress traffic boundaries to know when to apply translation rules.
2
Define an access list matching the internal subnet traffic.
Standard ACL permits 10.45.10.0 0.0.0.255.
The ACL acts as the interesting traffic filter to identify packets eligible for translation.
3
Configure the inside source PAT statement using the interface and overload keywords.
Command ip nat inside source list 1 interface GigabitEthernet0/0/1 overload is applied.
The overload keyword instructs Cisco IOS to track layer 4 TCP/UDP port numbers, enabling thousands of internal hosts to share one public IP address.

Anahtar Kavram

Inside Source PAT Configuration
Tahmini Süre:2m 0s
Soru 1637Soru →

A Cisco router receives an IP packet destined for host 172.20.16.68. The network engineer checks the routing table and observes the following entries:

text
C 172.20.16.0/23 is directly connected, GigabitEthernet0/0/0
S 172.20.16.0/25 [1/0] via 192.168.1.1, GigabitEthernet0/0/1
D 172.20.16.64/27 [90/2570240] via 192.168.1.5, GigabitEthernet0/0/2
O 172.20.16.64/28 [110/30] via 192.168.1.9, GigabitEthernet0/0/3

Which next-hop IP address and outgoing interface will the router select to forward this packet?

Cevabı ve açıklamayı göster

Cevap: Next-hop 192.168.1.9 via GigabitEthernet0/0/3

Cevap

The router will select next-hop 192.168.1.9 via interface GigabitEthernet0/0/3 because the /28 route provides the longest prefix match for destination 172.20.16.68.
When a router performs a destination lookup in the routing table, it evaluates all matching entries and selects the route with the most specific prefix length (Longest Prefix Match). The host address 172.20.16.68 falls within all four candidate subnet ranges, but 172.20.16.64/28 has the highest mask length (/28 > /27 > /25 > /23). Therefore, the router forwards the packet using next-hop 192.168.1.9 via GigabitEthernet0/0/3 regardless of the higher administrative distance of OSPF.

Adım Adım Çözüm

1
Determine which routing table entries match the destination IP address 172.20.16.68.
All four routes cover 172.20.16.68:
- 172.20.16.0/23 covers 172.20.16.0 - 172.20.17.255
- 172.20.16.0/25 covers 172.20.16.0 - 172.20.16.127
- 172.20.16.64/27 covers 172.20.16.64 - 172.20.16.95
- 172.20.16.64/28 covers 172.20.16.64 - 172.20.16.79
Before comparing metrics or administrative distance, the router must evaluate match candidates against the destination address.
2
Apply the Longest Prefix Match (LPM) rule to select the best route.
The subnet masks are /23, /25, /27, and /28. The /28 route is the most specific prefix (longest prefix match).
Cisco IP forwarding logic always prioritizes prefix length over administrative distance or metric when multiple matching routes exist.
3
Identify the next-hop and interface associated with the longest matching prefix.
The OSPF route 172.20.16.64/28 specifies next-hop 192.168.1.9 via GigabitEthernet0/0/3.
This entry dictates the forwarding decision.

Anahtar Kavram

Longest Prefix Match (LPM) in IP Routing
Soru 1638Soru →

Match each core network security term on the left with its corresponding enterprise security description on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Vulnerability
Threat
Exploit
Risk

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Vulnerability pairs with the unpatched operating system bug; Threat pairs with the malicious external actor; Exploit pairs with the crafted software script taking advantage of a flaw; Risk pairs with the likelihood and impact of an intrusion.
Vulnerability refers to a system flaw such as an unpatched OS bug. Threat describes the danger agent such as a malicious actor. Exploit is the actual method or script used to weaponize the flaw. Risk measures the calculated financial or operational impact resulting from a threat leveraging a vulnerability.

Adım Adım Çözüm

1
Review the formal definitions of key security terminology.
Differentiate between systemic weaknesses (vulnerability), external dangers (threat), attack tools (exploit), and calculated impact (risk).
CCNA security fundamentals require distinguishing between internal weaknesses, external danger vectors, attack implementations, and business exposure.
2
Match each term to the enterprise scenario.
Pair Vulnerability to the OS bug, Threat to the attacker, Exploit to the attack script, and Risk to the impact assessment.
Each scenario illustrates a distinct element of the risk and threat landscape.

Anahtar Kavram

Key Security Concepts: Threat, Vulnerability, Exploit, and Risk
Tahmini Süre:1m 0s
Soru 1639Soru →

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 1640Soru →

Match each SNMP component or operational term on the left with its correct defining characteristic on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

SNMP Trap
SNMP Inform
Management Information Base (MIB)
SNMPv3 authPriv

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

SNMP Trap matches the unacknowledged notification on UDP port 162; SNMP Inform matches the acknowledged notification requiring response; MIB matches the hierarchical database of OIDs; SNMPv3 authPriv matches the security level providing authentication and encryption.
Each SNMP term correctly maps to its defining operational characteristic. Traps provide unacknowledged alerts on UDP port 162, Informs provide acknowledged alerts, MIB represents the OID database structure, and SNMPv3 authPriv combines authentication with encryption.

Adım Adım Çözüm

1
Identify the transmission mechanics of SNMP notifications
Traps are unacknowledged notifications sent on UDP 162, while Informs use acknowledgments for reliable delivery.
Traps rely on best-effort UDP transmission, whereas Informs guarantee receipt via NMS confirmation messages.
2
Identify data structure definitions in SNMP
The MIB defines all readable and writable objects on a managed device structured hierarchically using OIDs.
Network Management Systems query or modify specific OID paths defined within the MIB schema.
3
Evaluate SNMPv3 security levels
authPriv stands for authentication and privacy (encryption).
Unlike noAuthNoPriv (no security) or authNoPriv (authentication without encryption), authPriv enforces both cryptographic verification and payload encryption.

Anahtar Kavram

SNMP Notification Types, MIB Structures, and Security Levels
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