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Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 1681Soru →

A network engineer configures port security on a Cisco Catalyst switch interface using the command `switchport port-security mac-address sticky`. The switch successfully learns the MAC address of the connected host and dynamically adds it to the running configuration. However, after the switch is rebooted, the port security configuration no longer retains the previously learned host MAC address. Which administrative oversight caused this issue?

Cevabı ve açıklamayı göster

Cevap: The engineer did not save the running configuration to the startup configuration after the MAC address was learned.

Cevap

The host MAC address was lost because the running configuration containing the learned sticky MAC address was not saved to the startup configuration prior to the switch reboot.
When port security is configured with sticky MAC learning, the switch dynamically converts learned MAC addresses into static-like entries within the running configuration (`running-config`). Because the running configuration resides in volatile RAM, any switch reboot causes these learned entries to be cleared unless an administrator explicitly copies the running configuration to the startup configuration in NVRAM using `copy running-config startup-config` or `write memory`.

Adım Adım Çözüm

1
Analyze how sticky MAC learning functions in Cisco Port Security.
Executing `switchport port-security mac-address sticky` instructs the switch to dynamically learn MAC addresses and write them into the volatile running configuration as `switchport port-security mac-address sticky <mac-address>` commands.
Understanding where learned MAC addresses are stored in switch memory helps identify persistence requirements.
2
Determine why volatile memory changes do not survive a switch reboot.
The running configuration is stored in RAM. Without running `copy running-config startup-config` or `write memory`, all RAM contents are lost when the device reboots.
RAM contents must be committed to non-volatile RAM (NVRAM) for settings to persist across reboots.

Anahtar Kavram

Port Security Sticky MAC Address Persistence and NVRAM Configuration Management
Tahmini Süre:45s
Soru 1682Soru →

An administrator needs to configure a Cisco router interface to relay incoming broadcast DHCP client discovery messages from the local client subnet on interface GigabitEthernet0/0 to a centralized DHCP server at IPv4 address 10.1.1.50. Which command must be applied under the GigabitEthernet0/0 interface mode to enable this relay service?

Cevabı ve açıklamayı göster

Cevap: ip helper-address 10.1.1.50

Cevap

The command 'ip helper-address 10.1.1.50' must be configured on the client-facing interface GigabitEthernet0/0.
The command 'ip helper-address 10.1.1.50' under interface configuration mode enables the router to listen for broadcast UDP requests (such as DHCP Discover/Request on ports 67/68) on that client interface and relay them as unicast traffic to the specified IP address 10.1.1.50.

Adım Adım Çözüm

1
Identify the incoming client interface and the remote DHCP server IP address.
The client-facing interface is GigabitEthernet0/0 and the target DHCP server IP address is 10.1.1.50.
DHCP relay agents must be enabled on the specific interface receiving incoming client broadcast requests.
2
Apply the Cisco IOS interface command that converts DHCP broadcasts into target unicast messages.
Entering interface configuration mode and executing 'ip helper-address 10.1.1.50'.
Cisco IOS uses the 'ip helper-address' command followed by the remote server IPv4 address to perform DHCP relay operations.

Anahtar Kavram

DHCP Relay Agent Interface Configuration
Tahmini Süre:45s
Soru 1683Soru →

A network engineer connects two Cisco Catalyst switches using a point-to-point GigabitEthernet link running Rapid PVST+. Place the steps of the Rapid PVST+ Proposal and Agreement handshaking process in the correct chronological order from first to last.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct chronological sequence for the Rapid PVST+ Proposal-Agreement handshake is: 1) Upstream switch sends a Proposal BPDU, 2) Downstream switch puts non-edge designated ports into Discarding state (sync), 3) Downstream switch sends an Agreement BPDU, 4) Upstream switch immediately transitions its designated port to Forwarding.
Rapid PVST+ achieves rapid convergence on full-duplex point-to-point links via an explicit handshake. First, an upstream switch sends a Proposal BPDU. Second, the receiving downstream switch performs synchronization by forcing all non-edge designated ports into the Discarding state. Third, the downstream switch returns an Agreement BPDU. Finally, the upstream switch receives the Agreement and immediately transitions its designated port to Forwarding.

Adım Adım Çözüm

1
Initiate Handshake
The upstream switch transmits a configuration BPDU with the Proposal bit set on a point-to-point link.
Rapid PVST+ uses explicit handshaking on point-to-point links rather than waiting for 802.1D forward delay timers.
2
Perform Synchronization
The receiving (downstream) switch blocks all non-edge designated ports, putting them into the Discarding state.
Enforcing the synchronization (sync) state isolates the local switch topology to ensure no temporary switching loops are formed.
3
Send Agreement
The downstream switch sends a BPDU back with the Agreement bit set.
This confirms to the upstream neighbor that the downstream switch has isolated its local ports and accepted the proposal.
4
Transition to Forwarding
The upstream switch transitions its designated port directly to the Forwarding state.
Receiving an explicit Agreement allows immediate state transition without waiting for timer expiration.

Anahtar Kavram

Rapid PVST+ (802.1w) Proposal-Agreement Synchronization Process
Tahmini Süre:1m 30s
Soru 1684Soru →

In a multi-vlan corporate topology, an end host attached to subinterface GigabitEthernet0/0.30 broadcasts a DHCP DISCOVER frame. The gateway router (R1) has subinterface GigabitEthernet0/0.30 configured with IPv4 address 192.168.30.1/24 and the ip helper-address 10.5.5.50 command pointing to a central DHCP server. When R1 processes and forwards this DHCP request to the server across the routed core, which field in the DHCP message header does R1 modify, and what specific value is inserted into that field?

Cevabı ve açıklamayı göster

Cevap: The Gateway IP Address (giaddr) field, populated with 192.168.30.1

Cevap

The correct answer specifies that the Gateway IP Address (giaddr) field is populated with 192.168.30.1.
When a router receives a broadcast DHCP message on an interface configured with `ip helper-address`, it acts as a DHCP Relay Agent. The router converts the broadcast into a unicast message sent to the IP specified in the `ip helper-address` command. Crucially, the router sets the `giaddr` (Gateway IP Address) field inside the DHCP header to the primary IPv4 address configured on the interface that received the client's broadcast (192.168.30.1). This informs the central DHCP server which IP pool/subnet to select an address from and provides the return path for the unicast DHCP OFFER.

Adım Adım Çözüm

1
Analyze client broadcast reception
The router receives the layer 2/3 broadcast (255.255.255.255 / UDP 67) from the client on subinterface GigabitEthernet0/0.30.
The client initial DHCP DISCOVER message is unnumbered and must be broadcast within its local broadcast domain (VLAN 30).
2
Examine relay agent processing
Because helper address 10.5.5.50 is configured on GigabitEthernet0/0.30, the router encapsulates the packet as a unicast IPv4 packet directed to 10.5.5.50.
Routers drop broadcast packets by default; the relay agent converts the broadcast to a unicast frame to traverse routed network hops.
3
Determine GIADDR field insertion
The router writes its receiving interface IP address (192.168.30.1) into the DHCP header giaddr (Gateway IP Address) field.
The DHCP server requires the giaddr field to match the incoming client gateway network address in order to select the corresponding scope (192.168.30.0/24) and route the unicast offer back to the relay agent.

Anahtar Kavram

DHCP Relay Agent GIADDR Field Operation
Soru 1685Soru →

A network administrator configures a Cisco IOS router with the command `logging trap 4` to send log messages to a remote syslog server. Which syslog severity levels will be forwarded to the server?

Cevabı ve açıklamayı göster

Cevap: Severity levels 0 through 4 (Emergency, Alert, Critical, Error, and Warning)

Cevap

Severity levels 0 through 4 (Emergency, Alert, Critical, Error, and Warning)
The command `logging trap 4` configures the router to forward syslog messages with a severity level equal to or lower in numerical value than 4. Because Cisco IOS assigns lower numerical values to higher severity events (0 = Emergency up to 7 = Debugging), level 4 (Warning) includes levels 0 (Emergency), 1 (Alert), 2 (Critical), 3 (Error), and 4 (Warning).

Adım Adım Çözüm

1
Recall the Cisco IOS syslog numerical severity scale.
Levels range from 0 to 7: 0=Emergency, 1=Alert, 2=Critical, 3=Error, 4=Warning, 5=Notice, 6=Informational, 7=Debugging.
Numerical values inversely relate to criticality; lower numbers represent higher severity.
2
Analyze the operational behavior of the `logging trap <level>` command.
The router sends all syslog messages with a numerical severity level equal to or less than the specified value.
The command establishes an upper numerical boundary for trapped messages.
3
Apply threshold level 4 (Warning) to the scale.
Log messages assigned levels 0, 1, 2, 3, and 4 are forwarded to the syslog server.
These levels are all less than or equal to numerical level 4.

Anahtar Kavram

Syslog Operations, Severity Levels, and Log Destination Configuration
Tahmini Süre:45s
Soru 1686Soru →

An engineer reviews the operational status of router R1 connected to a shared multiaccess Ethernet segment:

text
R1# show ip ospf interface GigabitEthernet0/1
GigabitEthernet0/1 is up, line protocol is up
Internet Address 10.10.10.1/24, Area 0
Process ID 10, Router ID 10.10.10.1, Network Type BROADCAST, Cost: 1
State DROTHER, Priority 0
Designated Router (ID) 10.10.10.3, Interface address 10.10.10.3
Backup Designated Router (ID) 10.10.10.2, Interface address 10.10.10.2

If both the Designated Router (DR) and Backup Designated Router (BDR) suffer a simultaneous hardware failure, which role will router R1 transition to on this broadcast segment?

Cevabı ve açıklamayı göster

Cevap: R1 will remain in the DROTHER state and will not participate in the election for DR or BDR.

Cevap

R1 will remain in the DROTHER state and will not participate in the election for DR or BDR.
In OSPFv2 multiaccess networks, setting an interface priority to 0 disqualifies the router from participating in the DR/BDR election process. Even if both the active DR and BDR fail, a router with a priority of 0 will stay in the DROTHER state and will never assume the DR or BDR role.

Adım Adım Çözüm

1
Inspect the interface priority value in the CLI snippet.
The interface priority on GigabitEthernet0/1 is set to 0 (`Priority 0`).
OSPF interface priority determines eligibility in DR/BDR elections.
2
Evaluate the OSPF DR/BDR election rules for priority 0.
A priority of 0 means the router is ineligible to become either DR or BDR.
Setting the priority to 0 is the administrative mechanism used to isolate a router from taking on DR or BDR election responsibilities.
3
Determine the operational state following DR and BDR failures.
R1 remains in the DROTHER state indefinitely until an eligible router (priority > 0) joins the segment.
Even if DR and BDR fail simultaneously, an ineligible router cannot be promoted.

Anahtar Kavram

OSPF Interface Priority 0 Election Exclusion
Tahmini Süre:1m 0s
Soru 1687Soru →

An administrator is troubleshooting an OSPFv2 neighbor relationship between two directly connected routers, R1 and R2. Output from the command `show ip ospf neighbor` on R1 displays the neighbor state for R2 as `INIT/ -`. Which condition is the most likely cause of this neighbor state?

Cevabı ve açıklamayı göster

Cevap: R1 is receiving OSPF Hello packets from R2, but R2 is not receiving OSPF Hello packets from R1.

Cevap

R1 is receiving OSPF Hello packets from R2, but R2 is not receiving OSPF Hello packets from R1.
The INIT state indicates that a router has received an OSPF Hello packet from a neighbor, but bidirectional communication has not yet been verified because the receiving router's own Router ID is not listed in the neighbor's Hello packet. This typically occurs due to unidirectional link failures or filtering (such as an ACL blocking traffic in one direction).

Adım Adım Çözüm

1
Analyze OSPF neighbor state definitions
Identify what the INIT state signifies in the OSPF neighbor state machine.
The INIT state means a valid OSPF Hello packet has been received from the neighbor, but two-way communication has not yet been established because the receiving router's own Router ID is missing from the neighbor's Hello Active Neighbor field.
2
Evaluate the cause of unidirectional Hello reception
Determine that R1 receives Hellos from R2, but R2 does not receive Hellos from R1.
If an access control list (ACL) or physical fault blocks packets in only one direction (from R1 to R2), R2 never sees R1's Hello, so R2 never includes R1's Router ID in its own sent Hellos. R1 continues receiving R2's Hellos and stays in the INIT state.
3
Differentiate from other failure states
Rule out MTU mismatch (ExStart/Exchange state), OSPF process ID mismatch (no impact), and priority 0 (prevents DR/BDR election only).
Understanding distinct neighbor states ensures accurate diagnosis of OSPF adjacency issues.

Anahtar Kavram

OSPFv2 Neighbor States and Unidirectional Communication
Soru 1688Soru →

Match each Cisco IPv4 routing table entry format on the left with its corresponding operational description on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

D 192.168.10.0/24 [90/2170112]
O 10.1.1.0/24 [110/65]
C 172.16.1.0/24
S 0.0.0.0/0 [1/0] via 192.168.1.1

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

D 192.168.10.0/24 [90/2170112] matches the EIGRP-learned route description; O 10.1.1.0/24 [110/65] matches the OSPF-learned route description; C 172.16.1.0/24 matches the directly connected route description; S 0.0.0.0/0 [1/0] via 192.168.1.1 matches the static default route description.
Each routing table notation correctly matches its protocol source code ('D' for EIGRP, 'O' for OSPF, 'C' for connected, 'S' for static) and accurately decodes the bracketed administrative distance and metric values.

Adım Adım Çözüm

1
Identify routing protocol source codes
Map 'D' to EIGRP, 'O' to OSPF, 'C' to Directly Connected, and 'S' to Static.
Cisco IOS routing tables use standard single-letter source codes to indicate route origins.
2
Interpret bracket notation [AD/Metric]
Extract administrative distance as the first value and route metric as the second value inside the brackets.
The bracketed syntax standardizes administrative distance (route trustworthiness) and metric (path cost).
3
Pair routing lines to functional descriptions
Match each left routing entry string with its corresponding description on the right.
Ensures all routing table components are correctly identified and defined.

Anahtar Kavram

Cisco IPv4 Routing Table Component Interpretation
Tahmini Süre:1m 30s
Soru 1689Soru →

A network engineer is configuring access control lists on an enterprise router to restrict network management traffic. The policy must allow a Network Management System (NMS) server to send SNMP query messages (such as GetRequest) to managed network devices, and also allow managed devices to send asynchronous event notifications (Traps and Informs) back to the NMS server. Which port and protocol combination must be permitted through the security filters to satisfy both operational requirements?

Cevabı ve açıklamayı göster

Cevap: UDP port 161 for SNMP queries sent to managed devices, and UDP port 162 for SNMP notifications sent to the NMS server.

Cevap

UDP port 161 for SNMP queries sent to managed devices, and UDP port 162 for SNMP notifications sent to the NMS server.
Simple Network Management Protocol (SNMP) uses UDP as its transport protocol. Managed devices run an SNMP agent that listens for incoming management requests (GetRequest, GetNextRequest, SetRequest) on UDP port 161. Conversely, the SNMP manager (NMS) listens for incoming asynchronous notification messages (Traps and Informs) on UDP port 162. Therefore, allowing UDP 161 towards managed devices and UDP 162 towards the NMS fulfills both monitoring requirements.

Adım Adım Çözüm

1
Identify the transport protocol used by standard SNMP operations.
SNMP utilizes UDP as its transport layer protocol for standard operations.
UDP provides low overhead connectionless transport appropriate for polling and notification delivery.
2
Determine the destination UDP port for agent polling operations (Get, GetNext, Set).
Managed devices (SNMP agents) listen on UDP port 161.
NMS managers send query requests to destination UDP port 161 on target network devices.
3
Determine the destination UDP port for notification messages (Traps and Informs).
NMS trap daemons listen on UDP port 162.
Managed devices send unsolicited Traps or acknowledged Informs to destination UDP port 162 on the management station.

Anahtar Kavram

SNMP Transport Layer Ports and Operational Mechanics
Soru 1690Soru →

Match each SNMP term or operation on the left with its defining characteristic on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

SNMP Trap
SNMP Inform
SNMP GetNext
Management Information Base (MIB)

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

SNMP Trap pairs with the unacknowledged notification on UDP port 162; SNMP Inform pairs with the reliable notification requiring NMS acknowledgment; SNMP GetNext pairs with the operation to walk consecutive OID entries; MIB pairs with the hierarchical database structure of managed objects.
Each item correctly matches its defining operational characteristic: SNMP Traps are unacknowledged alerts on UDP port 162, SNMP Informs are acknowledged alerts ensuring reliable delivery, SNMP GetNext sequentially iterates through MIB OIDs, and the MIB is the structured database of all managed object definitions.

Adım Adım Çözüm

1
Differentiate SNMP notification types based on delivery reliability.
Identify that SNMP Traps are fire-and-forget unacknowledged messages, while SNMP Informs require an explicit response packet from the SNMP manager.
Traps use UDP port 162 without delivery confirmation, whereas Informs store messages in memory until an acknowledgment is received.
2
Analyze SNMP manager request operations.
Identify that SNMP GetNext retrieves the next object instance in the MIB hierarchy.
GetNext allows traversal of structured data tables across an OID tree.
3
Define the role of the Management Information Base.
Recognize the MIB as the blueprint database defining object properties and OIDs.
The MIB organizes device data hierarchically so managers and agents speak a standardized variable namespace.

Anahtar Kavram

SNMP Operations, MIB Hierarchy, and Notification Delivery Mechanics
Soru 1691Soru →

An administrator needs to verify active Port Address Translation (PAT) sessions on a Cisco IOS router to inspect how inside local IP addresses and source port numbers are mapped to inside global addresses and translated port numbers. What exact Cisco IOS command displays the active NAT translation table?

Cevabı ve açıklamayı göster

Cevap: show ip nat translations; sh ip nat translations; show ip nat translation; sh ip nat trans

Cevap

show ip nat translations
The command 'show ip nat translations' displays all current active Network Address Translation and Port Address Translation mappings in the router's state table, showing exact protocol and port translations.

Adım Adım Çözüm

1
Identify the operational requirement for inspecting active PAT session mappings on a Cisco IOS router.
The objective requires displaying live translation bindings, including transport-layer protocol ports.
Active translation sessions are maintained dynamically in the router's active NAT translation table.
2
Specify the Cisco IOS privileged EXEC verification command that displays the translation table.
Executing 'show ip nat translations' prints the active list of translated addresses and port combinations.
This command outputs inside local, inside global, outside local, and outside global socket mappings.

Anahtar Kavram

Inside Source NAT and PAT Verification
Tahmini Süre:1m 0s
Soru 1692Soru →

An administrator examines the following routing table output on a Cisco router:

text
Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
O 10.15.0.0/16 [110/20] via 192.168.1.1, 00:10:22, GigabitEthernet0/0
D 10.15.10.0/24 [90/307200] via 192.168.2.1, 00:05:14, GigabitEthernet0/1
S 10.15.10.128/25 [1/0] via 192.168.3.1, 01:12:05, GigabitEthernet0/2
C 10.15.10.0/28 is directly connected, GigabitEthernet0/3

Which two statements regarding route selection and routing table components in this output are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Packets destined for host 10.15.10.130 are forwarded out interface GigabitEthernet0/2 because the subnet mask /25 provides the longest matching prefix for this destination.; The bracketed notation [90/307200] in the EIGRP entry indicates an administrative distance of 90 and a routing metric of 307200.

Cevap

The two correct statements are that packets destined for host 10.15.10.130 are forwarded out interface GigabitEthernet0/2 due to longest prefix match (/25), and that the bracketed notation [90/307200] represents an administrative distance of 90 and a metric of 307200.
Longest prefix match is the primary rule for IP packet forwarding. Destination 10.15.10.130 matches 10.15.10.128/25 with a 25-bit mask, which is longer than /24 or /16, causing forwarding via GigabitEthernet0/2. Additionally, standard Cisco routing table format displays administrative distance first and metric second inside square brackets, making [90/307200] represent an AD of 90 and a metric of 307200.

Adım Adım Çözüm

1
Evaluate destination host 10.15.10.130 against all matching routes in the routing table.
Matches 10.15.0.0/16, 10.15.10.0/24, and 10.15.10.128/25.
The router applies the longest prefix match rule, selecting /25 (10.15.10.128/25 via GigabitEthernet0/2).
2
Interpret routing table bracketed components [AD/Metric].
[90/307200] corresponds to AD 90 and Metric 307200.
The first number inside the brackets is always administrative distance and the second number is the routing metric.

Anahtar Kavram

Routing Table Lookup Logic & Component Interpretation
Soru 1693Soru →

A network administrator is troubleshooting an issue where event notifications sent from a Cisco IOS XE router to a central Network Management System (NMS) are lost during network congestion. The router is currently configured with the following command:

`snmp-server host 10.10.20.50 traps version 2c public`

Which configuration change must the administrator make on the router to ensure that event notifications require application-layer acknowledgments from the NMS and are automatically retransmitted if dropped?

Cevabı ve açıklamayı göster

Cevap: Replace the keyword traps with informs in the snmp-server host command.

Cevap

Replacing the keyword 'traps' with 'informs' in the 'snmp-server host' command configures SNMP Informs, which require application-level acknowledgment from the receiver and support automatic retransmissions.
Configuring SNMP Informs instead of SNMP Traps provides reliable notification delivery. Unlike Traps, which are unacknowledged UDP messages, Informs require the NMS recipient to respond with an acknowledgment. If the router does not receive an acknowledgment within the specified timeout, it retransmits the Inform PDU.

Adım Adım Çözüm

1
Analyze the operational difference between SNMP Traps and SNMP Informs.
SNMP Traps are unacknowledged notifications sent via UDP from an agent to an NMS. If a Trap packet is dropped in transit, the router has no mechanism to detect the loss or attempt retransmission. SNMP Informs require the NMS to reply with an SNMP response PDU to acknowledge receipt.
Understanding notification types is essential for selecting reliable event logging in network monitoring.
2
Identify the Cisco IOS syntax required to enable acknowledged notifications.
The command syntax `snmp-server host <ip-address> informs version <1 | 2c | 3> <community-string>` configures the router to send Informs rather than Traps.
Changing the keyword from 'traps' to 'informs' instructs Cisco IOS to store the notification in memory and retransmit it until an acknowledgment is received or the timeout threshold expires.

Anahtar Kavram

SNMP Traps vs Informs operational mechanics and Cisco IOS host configuration
Soru 1694Soru →

A network administrator needs to configure a floating static route on router R1 to serve as a backup path for the 192.168.100.0/24192.168.100.0/24 network. The primary path to this destination is currently learned dynamically via OSPF, which uses a default Administrative Distance of 110110. Which TWO statements correctly describe the requirements and operational behavior for this floating static route configuration?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The floating static route must be configured with an Administrative Distance value greater than 110.; The floating static route will only be installed into the routing table when the primary OSPF route disappears from the routing table.

Cevap

The floating static route must be configured with an Administrative Distance greater than 110, and it will only be installed into the routing table after the primary OSPF route is removed.
A floating static route acts as an inactive backup line that only takes effect when the primary path goes down. Because Cisco IOS evaluates route preference using Administrative Distance (where lower is preferred), the backup static route must be configured with an AD higher than the primary protocol's AD (in this case, higher than OSPF's default AD of 110). Consequently, the backup route stays inactive in the background and is only installed into the IP routing table when the primary OSPF route is withdrawn.

Adım Adım Çözüm

1
Identify the Administrative Distance (AD) of the primary routing protocol.
OSPF has a default AD of 110.
Administrative Distance defines route trustworthiness; lower values are preferred.
2
Determine the AD requirement for a backup (floating) static route.
The backup route AD must be strictly greater than 110 (e.g., 120).
If the AD were equal or lower, the router would prefer or load balance with the static route, preventing it from functioning strictly as a backup.
3
Analyze how Cisco IOS handles routing table selection with floating static routes.
The floating static route remains hidden from the routing table as long as the OSPF route (AD 110) exists.
When the primary OSPF route fails and is removed, the floating static route becomes the best available path for that destination prefix and is installed into the active routing table.

Anahtar Kavram

Floating Static Route AD Requirements and Routing Table Selection
Soru 1695Soru →

A network administrator is configuring SSH version 2 on a freshly unpacked Cisco IOS router. Which TWO configuration steps are required before the router will allow the generation of RSA host keys using the 'crypto key generate rsa' command? (Choose two.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Configure a non-default device hostname using the 'hostname' command; Configure an IP domain name using the 'ip domain name' command

Cevap

The correct prerequisites are configuring a non-default hostname and setting an IP domain name.
Generating RSA keys on Cisco IOS depends directly on having a fully qualified domain name (FQDN). The FQDN is formed by combining the device hostname and the configured IP domain name. Therefore, both setting a unique hostname and defining an IP domain name are mandatory prerequisites prior to issuing the RSA key generation command.

Adım Adım Çözüm

1
Identify the requirement for RSA key generation in Cisco IOS
The router uses the combination of the hostname and IP domain name to construct the Fully Qualified Domain Name (FQDN) key pair label.
Without a custom hostname (other than the default 'Router') and an IP domain name, the key generation command will fail.
2
Differentiate prerequisite host key configuration steps from VTY line binding steps
Hostname and domain name must be configured before executing 'crypto key generate rsa'. Line VTY commands like 'login local' and 'transport input ssh' are applied afterward to manage connection access.
RSA key creation is a system-level cryptographic prerequisite for initializing the SSH daemon.

Anahtar Kavram

Prerequisites for generating RSA key pairs for SSH remote access on Cisco IOS devices
Soru 1696Soru →

A network engineer is assigned the IPv4 block 10.100.0.0/2110.100.0.0/21 to create subnetworks for regional offices. Each regional office network requires a /26/26 subnet mask. How many /26/26 subnetworks can be created from this 10.100.0.0/2110.100.0.0/21 block?

Cevabı ve açıklamayı göster

Cevap: 32

Cevap

32 subnets can be created from the 10.100.0.0/2110.100.0.0/21 block.
Subtracting the original prefix length (/21/21) from the new subnet prefix length (/26/26) yields 55 subnet bits (26−21=526 - 21 = 5). Calculating 252^5 gives 3232 subnets available within the 10.100.0.0/2110.100.0.0/21 parent block.

Adım Adım Çözüm

1
Determine the number of subnet bits borrowed by subtracting the initial block prefix length from the target subnet prefix length.
Borrowed bits = 26−21=526 - 21 = 5 bits.
The difference between the new prefix length and the original prefix length represents the bits available to create subnets.
2
Calculate the total number of subnets using 2n2^n, where nn is the number of borrowed bits.
25=322^5 = 32 subnets.
Each additional bit assigned to the network prefix doubles the number of valid subnets.

Anahtar Kavram

Calculating Subnet Count from CIDR Prefix Differences
Tahmini Süre:1m 30s
Soru 1697Soru →

A network administrator is troubleshooting an intermittent first-hop gateway issue on a dual-homed router pair (R1R1 and R2R2) providing redundancy for VLAN 50 (172.20.50.0/24172.20.50.0/24). R1R1 is intended to be the active HSRP router under normal operational conditions.

The interface configurations are shown below:

text
R1# show running-config interface GigabitEthernet0/1
interface GigabitEthernet0/1
ip address 172.20.50.2 255.255.255.0
standby 50 ip 172.20.50.1
standby 50 priority 115
standby 50 track GigabitEthernet0/0 20

R2# show running-config interface GigabitEthernet0/1
interface GigabitEthernet0/1
ip address 172.20.50.3 255.255.255.0
standby 50 ip 172.20.50.1
standby 50 priority 105
standby 50 preempt

When the uplink interface GigabitEthernet0/0 on R1R1 fails, R1R1's priority drops from 115 to 95 (115−20115 - 20), allowing R2R2 (priority 105, preemption enabled) to take over as the Active router. However, when GigabitEthernet0/0 on R1R1 recovers and its priority returns to 115, R2R2 remains the Active router and R1R1 stays in Standby state.

Which configuration change on R1R1 will resolve this issue so that R1R1 automatically reclaims the Active HSRP role upon link recovery?

Cevabı ve açıklamayı göster

Cevap: Configure standby 50 preempt under interface GigabitEthernet0/1 on R1.

Cevap

Enabling preemption on R1 using the command 'standby 50 preempt' allows R1 to reclaim the Active gateway role after its tracked interface recovers.
By default, HSRP preemption is disabled. Even if a router has a higher priority than the current Active router, it will not attempt to take over the Active role unless preemption is explicitly configured using the 'standby <group> preempt' command. On R1, once its tracked interface recovered, its priority returned to 115 (higher than R2's 105), but because preemption was missing on R1, it remained in the Standby state. Adding 'standby 50 preempt' to R1 resolves the issue.

Adım Adım Çözüm

1
Analyze initial HSRP priorities and roles
R1 has priority 115 and R2 has priority 105. R1 is Active.
Higher priority determines the Active HSRP router.
2
Evaluate failover behavior when R1's tracked interface fails
R1 priority drops to 95 (115 - 20). R2 has priority 105 and 'standby 50 preempt' enabled, so R2 takes over as Active.
R2 has preemption enabled and its priority (105) is now higher than R1's reduced priority (95).
3
Evaluate recovery behavior when R1's tracked interface comes back up
R1 priority returns to 115, but R1 remains Standby because it lacks the 'standby 50 preempt' command.
Without preemption explicitly configured, an HSRP router with a higher priority will not preempt an already operational Active router.
4
Determine the required configuration fix
Adding 'standby 50 preempt' to R1 allows it to preempt R2 (115 > 105) once priority is restored upon link recovery.
Preemption must be enabled on the router that needs to reclaim the Active state.

Anahtar Kavram

HSRP Preemption and Interface Tracking Mechanics
Soru 1698Soru →

An administrator inspects the output of the `show ntp associations` command on router Core-R1:

text
address ref clock st when poll reach delay offset disp
*~192.168.50.2 10.1.1.1 2 15 64 377 2.12 0.18 0.45
~192.168.60.2 127.127.1.1 16 - 64 0 0.00 0.00 16000.

Core-R1 is also configured with the `ntp master 6` command. Router Branch-R2 is configured to synchronize its clock with Core-R1 using the command `ntp server 192.168.10.1` (Core-R1's IP address).

Which statement accurately describes the resulting NTP operational status and stratum hierarchy for both devices once synchronization is fully established?

Cevabı ve açıklamayı göster

Cevap: Core-R1 operates at Stratum 3, and Branch-R2 operates at Stratum 4.

Cevap

Core-R1 operates at Stratum 3, and Branch-R2 operates at Stratum 4.
In Cisco IOS NTP operation, an asterisk (`*`) in `show ntp associations` designates the current synchronized time source. Because 192.168.50.2 is at Stratum 2, Core-R1 becomes Stratum 3 (2+1=32 + 1 = 3). The `ntp master` command acts only as an authoritative clock fallback when no synchronized upstream clock is present, so `ntp master 6` is inactive. Consequently, Branch-R2 synchronizing to Core-R1 receives Stratum 3 time and becomes Stratum 4 (3+1=43 + 1 = 4).

Adım Adım Çözüm

1
Analyze the output of `show ntp associations` on Core-R1.
The asterisk `*` next to `192.168.50.2` indicates that Core-R1 is actively synchronized to this server. The `st` column shows that this server operates at Stratum 2.
An NTP client increments the stratum value of its configured reference clock by 11.
2
Evaluate the impact of the `ntp master 6` command on Core-R1.
Core-R1's effective stratum is 2+1=32 + 1 = 3. The `ntp master 6` setting is ignored.
The `ntp master` command serves as a fallback clock source only when no active, valid external NTP server is synchronized.
3
Calculate the stratum level for Branch-R2.
Branch-R2 synchronizes to Core-R1 (Stratum 3), resulting in a stratum level of 3+1=43 + 1 = 4 for Branch-R2.
Each hop down the NTP distribution tree adds 11 to the stratum level.

Anahtar Kavram

NTP Stratum Hierarchy and Precedence
Tahmini Süre:2m 0s
Soru 1699Soru →

A network administrator is inspecting interface configuration settings on a Cisco Catalyst switch after a user host on FastEthernet0/12 fails to communicate with devices in the target network. The output from the command `show interfaces FastEthernet0/12 switchport` indicates the following:

text
Name: Fa0/12
Switchport: Enabled
Administrative Mode: dynamic auto
Operational Mode: static access
Access Mode VLAN: 1 (default)

Which combination of interface configuration commands must the administrator execute on FastEthernet0/12 to explicitly set the port as a static access port and assign it to VLAN 45?

Cevabı ve açıklamayı göster

Cevap: switchport mode access
switchport access vlan 45

Cevap

To configure FastEthernet0/12 as a static access port in VLAN 45, the administrator must enter interface configuration mode for FastEthernet0/12 and apply 'switchport mode access' followed by 'switchport access vlan 45'.
To configure a switch port as a static access member of a specific VLAN, Cisco IOS requires two commands under interface configuration mode: 'switchport mode access' to define the operational mode as access, and 'switchport access vlan <vlan-id>' to associate the interface with the specific VLAN ID.

Adım Adım Çözüm

1
Change interface operational mode to static access
Disables dynamic trunking negotiation attempts on the interface and hardcodes it as an access port
The 'switchport mode access' command forces the interface into static access mode.
2
Assign the interface to the designated broadcast domain
Traffic received on FastEthernet0/12 is tagged/placed into VLAN 45
The 'switchport access vlan 45' command specifies VLAN 45 as the access VLAN for untagged frames.

Anahtar Kavram

Cisco IOS Switchport Access Mode and VLAN Membership Configuration
Soru 1700Soru →

A network administrator is setting up a branch office deployment with Cisco Access Points (APs) operating in FlexConnect mode. The APs need to locally switch traffic for client WLANs mapped to corporate VLAN 20 and guest VLAN 30, while using VLAN 10 for AP management and CAPWAP control traffic back to the WLC. Which switch port configuration must be applied to the switch interface connected to each FlexConnect AP?

Cevabı ve açıklamayı göster

Cevap: Configure the switch port as an 802.1Q trunk port with Native VLAN 10 and allowed VLANs 10, 20, and 30.

Cevap

The switch port must be configured as an 802.1Q trunk port with Native VLAN 10 (for untagged AP management/CAPWAP traffic) and allowed VLANs 10, 20, and 30 for local client traffic switching.
FlexConnect APs configured for local switching handle client traffic locally at the branch level. To support multiple SSIDs mapped to different VLANs (VLAN 20 and 30) alongside AP management traffic (VLAN 10), the connected switch port must be an 802.1Q trunk. Untagged AP management traffic maps to the native VLAN (VLAN 10), while client traffic is tagged with its respective local VLAN IDs.

Adım Adım Çözüm

1
Identify the operational mode of the Access Point.
The AP is in FlexConnect mode performing local switching for client traffic.
FlexConnect APs process VLAN tags locally on their physical Ethernet interfaces for traffic sent directly to the local switch infrastructure.
2
Determine the interface type required on the switch.
An 802.1Q trunk interface is required because multiple VLANs (VLAN 10, 20, 30) must traverse the single link connecting the AP.
Access ports can only carry a single VLAN, which is insufficient for multi-VLAN local switching.
3
Determine Native VLAN assignment for AP management.
Set Native VLAN to VLAN 10 on the switch trunk port.
Cisco APs transmit untagged management traffic by default. The native VLAN on the switch trunk port ensures untagged packets from the AP are placed onto management VLAN 10.

Anahtar Kavram

FlexConnect AP Infrastructure Switch Port Trunking Requirements
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