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Tüm alıştırma soruları

1987 soru

Tüm türler1,987Çoktan seçmeli1,020Çoklu seçim452Sayısal18Eşleştirme229Sıralama203Boşluk doldurma22Kısa cevap43
Soru 321Soru →

A network administrator is troubleshooting neighbor visibility on a Cisco Catalyst switch (SW-1) connected to a non-Cisco switch. The administrator executes the `show lldp entry Core-SW2` command on SW-1 and receives the following CLI output:

text
Local Interface: Gi1/0/24
Chassis id: 0014.f2ca.8800
Port id: Eth1/1
Port Description: Trunk-to-Core1
System Name: Core-SW2

System Description:
Cisco Nexus Operating System (NX-OS) Software, Version 9.3(5)

Time remaining: 92 seconds
System Capabilities: B, R
Enabled Capabilities: B, R

Management Addresses:
IP: 10.1.100.2

Auto Negotiation: supported, enabled
Physical media capabilities:
1000baseT(FD)

Media Attachment Unit type: 30
VLAN Advertised: 10, 20, 99
Port VLAN ID (PVID): 99

Based on this LLDP detailed output, which conclusion correctly interprets the neighbor properties and link configuration?

Cevabı ve açıklamayı göster

Cevap: The local switch interface receiving the LLDP frames is GigabitEthernet1/0/24, while the remote neighbor's egress port is Ethernet1/1 with a native VLAN (PVID) of 99.

Cevap

The local switch interface receiving the LLDP frames is GigabitEthernet1/0/24, while the remote neighbor's egress port is Ethernet1/1 with a native VLAN (PVID) of 99.
In Cisco IOS LLDP detailed entries (`show lldp entry` or `show lldp neighbors detail`), 'Local Interface' indicates the interface on the local device where the frame arrived (Gi1/0/24). The 'Port id' field identifies the remote neighboring device's egress interface (Eth1/1). Furthermore, the 'Port VLAN ID (PVID)' field reflects the native VLAN advertised by the adjacent device for that link.

Adım Adım Çözüm

1
Analyze the Local Interface and Port ID fields in the LLDP output
'Local Interface: Gi1/0/24' represents the local switch's port receiving the LLDP frame. 'Port id: Eth1/1' specifies the interface on the remote neighboring device (Core-SW2).
LLDP output explicitly distinguishes between the local port where traffic is received and the remote port ID advertised by the neighbor.
2
Examine the Port VLAN ID (PVID) TLV information
'Port VLAN ID (PVID): 99' is the native VLAN ID advertised by the neighbor device (Core-SW2) for its port Eth1/1.
IEEE 802.1AB LLDP includes Organizationally Specific TLVs that advertise port attributes of the remote sender, including its configured native VLAN (PVID).
3
Evaluate the remaining timer information
'Time remaining: 92 seconds' is the dynamic countdown timer before the cached entry expires, not the configured holdtime constant.
The default LLDP holdtime multiplier (4) with a default message frequency (30s) yields a default holdtime of 120s; 92 seconds is merely the current countdown state.

Anahtar Kavram

Interpretation of LLDP Detailed CLI Neighbor Data and IEEE 802.1AB TLVs
Tahmini Süre:2m 0s
Soru 322Soru →

A network administrator is evaluating the IPv4 configuration on a core router interface assigned the IP address 172.31.223.254/22172.31.223.254/22. Which of the following statements regarding this IPv4 addressing assignment are correct? (Select TWO.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The configured interface IP address represents the last usable host IP address within the subnet.; The IP address falls within the RFC 1918 private IPv4 address space.

Cevap

The statements confirming that the configured interface IP address is the last usable host within the subnet and that the IP address belongs to the RFC 1918 private IPv4 space are correct.
The subnet mask 255.255.252.0 (/22) creates subnets in increments of 4 in the third octet. For 172.31.223.254, the network address is 172.31.220.0 and the broadcast address is 172.31.223.255. Therefore, 172.31.223.254 is the last assignable host address in the subnet. Furthermore, RFC 1918 specifies the Class B private range as 172.16.0.0 to 172.31.255.255, so this address is a valid private IPv4 address.

Adım Adım Çözüm

1
Determine host bits and total/usable address capacity for a /22 prefix.
A /22 prefix leaves 32−22=1032 - 22 = 10 host bits. Total addresses = 210=1,0242^{10} = 1,024. Usable host capacity = 210−2=1,0222^{10} - 2 = 1,022 host addresses.
Network ID and broadcast ID cannot be assigned to individual endpoints.
2
Calculate subnet network boundaries for 172.31.223.254/22172.31.223.254/22.
The subnet mask is 255.255.252.0255.255.252.0. The third octet block size is 256−252=4256 - 252 = 4. Multiplying by 55 yields 55×4=22055 \times 4 = 220. The network ID is 172.31.220.0/22172.31.220.0/22, and the broadcast address is 172.31.223.255172.31.223.255.
Finding the block size in the interesting octet identifies the network boundary and broadcast address.
3
Determine the usable host IP address range.
The usable range is 172.31.220.1172.31.220.1 through 172.31.223.254172.31.223.254. Thus, 172.31.223.254172.31.223.254 is the last assignable host address.
Usable host addresses lie strictly between the network ID and the broadcast ID.
4
Verify RFC 1918 private address range compliance.
RFC 1918 designates 172.16.0.0/12172.16.0.0/12 (172.16.0.0−172.31.255.255172.16.0.0 - 172.31.255.255) as private space. 172.31.223.254172.31.223.254 falls directly within this block.
Checking official RFC 1918 prefix allocations determines public versus private status.

Anahtar Kavram

IPv4 subnet boundary calculation, usable host calculation (2n−22^n - 2), and RFC 1918 private IP address range boundaries.
Soru 323Soru →

A network technician notices that connecting an end-user host to an access port does not generate a Topology Change Notification (TCN) or cause MAC address table flushing on neighboring switches. Which feature configured on the access interface is responsible for suppressing these STP topology change notifications upon link state changes?

Cevabı ve açıklamayı göster

Cevap: PortFast

Cevap

PortFast suppresses Topology Change Notifications (TCNs) when edge interfaces change state, avoiding unnecessary MAC table flushing across the network.
PortFast is intended for switch ports connected to end devices. Besides bypassing the Listening and Learning states to transition immediately to Forwarding, PortFast ensures that link state changes on edge ports do not trigger Spanning Tree Topology Change Notifications (TCNs), thereby protecting the network from unnecessary MAC address table aging and flushing.

Adım Adım Çözüm

1
Identify the STP behavior caused by connecting end-user devices.
Standard 802.1D STP generates a Topology Change Notification (TCN) whenever a link comes up or goes down, causing switches in the broadcast domain to shorten their MAC address table aging timer.
End-user workstations power on and off frequently, which would cause constant MAC table flushing if TCNs were transmitted.
2
Evaluate the role of PortFast.
PortFast designates a port as an edge port, immediately transitioning it to Forwarding while suppressing TCN generation upon link state changes.
Since end-user workstations do not interconnect switches, link state changes on these ports do not affect the overall Spanning Tree topology.

Anahtar Kavram

PortFast TCN Suppression and Edge Port Operation
Soru 324Soru →

An engineer inspects the IPv6 neighbor discovery table on a Cisco router and observes the dynamically generated link-local address fe80::2e0:a3ff:fe14:5678 assigned to an auto-configured host interface. Based on the standard EUI-64 calculation process, what is the original burned-in MAC address of the host network interface card?

Cevabı ve açıklamayı göster

Cevap: 00e0.a314.5678

Cevap

The original burned-in MAC address of the host network interface card is 00e0.a314.5678.
To reverse the EUI-64 process for the interface ID 02e0:a3ff:fe14:5678, first remove the 16-bit 'FFFE' inserted into the middle, which leaves 02e0.a314.5678. Next, invert the 7th bit (Universal/Local bit) in the first byte. Hexadecimal 02 is binary 00000010; inverting the 7th bit produces binary 00000000 (hexadecimal 00). Therefore, the original MAC address is 00e0.a314.5678.

Adım Adım Çözüm

1
Isolate the 64-bit interface identifier from the link-local IPv6 address
The interface identifier portion of fe80::2e0:a3ff:fe14:5678 is 02e0:a3ff:fe14:5678.
Link-local addresses append a 64-bit interface identifier to the fe80::/64 prefix.
2
Remove the 16-bit FFFE value inserted into the middle of the EUI-64 interface identifier
Removing 'ff:fe' from 02e0:a3ff:fe14:5678 leaves 02e0:a314:5678.
The EUI-64 process creates a 64-bit interface ID from a 48-bit MAC by inserting FFFE (1111 1111 1111 1110) between the 3rd and 4th bytes of the MAC address.
3
Invert the 7th bit (Universal/Local bit) of the first octet to restore the original MAC address
First octet 02 (0000 0010 binary) inverted at the 7th bit yields 00 (0000 0000 binary), resulting in MAC 00e0.a314.5678.
EUI-64 generation flips the 7th bit of the first byte (changing 0 for universal to 1 for local); reversing the process requires flipping this bit back.

Anahtar Kavram

Reversing standard IPv6 EUI-64 interface identifier generation to recover the original 48-bit MAC address
Tahmini Süre:1m 30s
Soru 325Soru →

An enterprise network relies on standard Syslog services over UDP port 514 to collect event logs from remote edge switches. When comparing transport protocol characteristics, which header feature directly accounts for UDP's lower processing overhead compared to TCP?

Cevabı ve açıklamayı göster

Cevap: UDP utilizes a fixed 8-byte header that omits fields for connection state tracking, flow control, and acknowledgments.

Cevap

UDP utilizes a fixed 8-byte header that omits fields for connection state tracking, flow control, and acknowledgments.
UDP is designed for low-overhead, best-effort transport. Its header contains only 4 fields totaling 8 bytes: Source Port (2 bytes), Destination Port (2 bytes), Length (2 bytes), and Checksum (2 bytes). By leaving reliability, sequencing, and flow control to application layers or accepting packet loss, UDP avoids the 20-byte minimum header and state maintenance required by TCP.

Adım Adım Çözüm

1
Analyze transport layer header structures
TCP headers require a minimum of 20 bytes to support sequence numbers, acknowledgment numbers, window sizes, flags, and control mechanisms. UDP headers consist of only 8 bytes (4 fields: Source Port, Destination Port, Length, and Checksum).
Lower header size directly reduces data overhead per packet.
2
Evaluate protocol feature set differences
UDP is connectionless and stateless. It does not establish sessions, manage flow control (windowing), perform segment sequencing, or require ACKs.
Omitting operational state management reduces router/host CPU and memory processing overhead.

Anahtar Kavram

TCP vs UDP Header Overhead and Protocol Mechanics
Soru 326Soru →

A network administrator is verifying IPv6 autoconfiguration on a Cisco router interface. The interface has a burned-in MAC address of `7069.5a12.3456` and is configured with the command `ipv6 address 2001:db8:abc:10::/64 eui-64`. Based on standard EUI-64 interface identifier construction and IPv6 address formats, which TWO statements regarding the resulting IPv6 configuration on this interface are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The derived 64-bit EUI-64 interface identifier for this interface is `7269:5aff:fe12:3456`.; The dynamically generated link-local IPv6 address for this interface begins with the `fe80::/10` prefix combined with the modified interface identifier.

Cevap

The two correct statements are: (1) The derived 64-bit EUI-64 interface identifier for this interface is `7269:5aff:fe12:3456`, and (2) The dynamically generated link-local IPv6 address for this interface begins with the `fe80::/10` prefix combined with the modified interface identifier.
Generating an IPv6 EUI-64 interface identifier from a 48-bit MAC address requires two transformations: toggling the 7th bit of the first byte (changing 0x70 to 0x72) and inserting FFFE into the midpoint, forming the 64-bit identifier `7269:5aff:fe12:3456`. Additionally, IPv6 automatically configures a link-local address on the interface using the designated prefix `fe80::/10` combined with this EUI-64 identifier.

Adım Adım Çözüm

1
Split the 48-bit MAC address into two 24-bit halves
Left half: `70-69-5A`, Right half: `12-34-56`
EUI-64 generation requires inserting a 16-bit delimiter into the middle of the MAC address.
2
Invert the 7th bit (Universal/Local bit) of the first byte
First byte `0x70` in binary is `0111 0000`. Inverting the 7th bit (2nd least significant bit of first byte) yields `0111 0010` in binary, which is `0x72`. The first half becomes `7269.5a`.
Inverting the U/L bit indicates that the address has been modified for global uniqueness scoping in IPv6 EUI-64.
3
Insert `FFFE` at the midpoint between the two halves
`7269:5A` + `FFFE` + `:123456` = `7269:5aff:fe12:3456`
This expands the 48-bit MAC address into a 64-bit interface identifier.
4
Verify the link-local prefix and global unicast address formation
Link-local address = `fe80::7269:5aff:fe12:3456`, Global unicast address = `2001:db8:abc:10:7269:5aff:fe12:3456`
Link-local addresses always use the `fe80::/10` prefix block (specifically formatted as `fe80::/64`).

Anahtar Kavram

IPv6 EUI-64 Interface Identifier Derivation and Link-Local Address Scoping
Tahmini Süre:2m 0s
Soru 327Soru →

A network engineer inspects packet captures from a server connection and notes a transport layer header size of 20 bytes featuring Sequence Number and Window Size fields. Which statement correctly identifies the transport protocol in use and its operational trade-off relative to UDP?

Cevabı ve açıklamayı göster

Cevap: The packet uses TCP, which provides reliable connection-oriented delivery and flow control but incurs higher header overhead and processing delay than UDP.

Cevap

The packet uses TCP, which provides reliable connection-oriented delivery and flow control but incurs higher header overhead and processing delay than UDP.
The presence of a 20-byte header along with Sequence Number and Window Size fields indicates the Transmission Control Protocol (TCP). TCP is connection-oriented and stateful, providing retransmission, sequencing, and flow control. The trade-off for these features is higher header overhead (20 bytes minimum compared to UDP's fixed 8 bytes) and additional latency required for state tracking.

Adım Adım Çözüm

1
Analyze the header characteristics in the packet capture.
Identified a 20-byte transport header with Sequence Number and Window Size fields.
These fields and the 20-byte minimum size specifically belong to the TCP header; UDP headers are fixed at 8 bytes.
2
Evaluate protocol operational mechanics and trade-offs.
TCP provides stateful, reliable connection management and windowing-based flow control at the cost of higher overhead.
The extra header fields (20 bytes vs UDP's 8 bytes) and acknowledgment mechanisms guarantee in-order delivery but introduce latency and bandwidth overhead.

Anahtar Kavram

TCP vs UDP Header Overhead and Reliability Mechanics
Soru 328Soru →

A network administrator needs to configure a fully specified IPv6 static route on a Cisco router to reach the remote network 2001:DB8:ACAD:1::/642001:\text{DB8}:\text{ACAD}:1::/64 using the neighbor router's link-local address FE80::2\text{FE80}::2 reachable via the local GigabitEthernet0/1\text{GigabitEthernet0/1} interface. Which command correctly configures this route?

Cevabı ve açıklamayı göster

Cevap: ipv6 route 2001:DB8:ACAD:1::/64 GigabitEthernet0/1 FE80::2

Cevap

The command 'ipv6 route 2001:DB8:ACAD:1::/64 GigabitEthernet0/1 FE80::2' correctly configures the fully specified IPv6 static route.
When configuring an IPv6 static route using a link-local address as the next-hop, Cisco IOS mandates a fully specified route that includes both the local exit interface and the link-local address of the adjacent router.

Adım Adım Çözüm

1
Identify the mandatory components of an IPv6 static route command with a link-local next hop.
The general syntax requires specifying both the local exit interface and the link-local next-hop address: 'ipv6 route <prefix/mask> <exit-interface> <link-local-address>'.
Because IPv6 link-local addresses (FE80::/10) are only unique on a single local link, Cisco IOS cannot determine which outbound interface to use unless the interface is explicitly defined.
2
Evaluate the specified parameters.
Destination prefix = 2001:DB8:ACAD:1::/64, Exit interface = GigabitEthernet0/1, Next-hop = FE80::2.
Combining these exact parameters in order produces a valid fully specified static route configuration.

Anahtar Kavram

Fully specified IPv6 static routes requiring both an exit interface and link-local next-hop address.
Soru 329Soru →

A network administrator is configuring Port Address Translation (PAT) on an enterprise Cisco IOS router. The internal subnets matched by Access Control List 15 require multiple internal IP addresses to share a dynamic pool of public IPv4 addresses named GUESTNATPOOLGUEST_NAT_POOL. Which Cisco IOS global configuration command correctly enables PAT using this dynamic address pool?

Cevabı ve açıklamayı göster

Cevap: ip nat inside source list 15 pool GUEST_NAT_POOL overload

Cevap

The correct command to configure dynamic PAT using an IP address pool is 'ip nat inside source list 15 pool GUEST_NAT_POOL overload'.
The correct command syntax for dynamic NAT with PAT using an IP address pool is 'ip nat inside source list <acl-number> pool <pool-name> overload'. The 'overload' keyword enables Layer 4 source port tracking so multiple internal IP addresses can share the IP addresses in the pool simultaneously.

Adım Adım Çözüm

1
Identify the source direction and dynamic NAT type
Inside source traffic matching an ACL requires 'ip nat inside source list <ACL>'.
Internal private hosts initiating outbound connections must undergo inside source NAT.
2
Specify the target public address pool
Append 'pool GUEST_NAT_POOL' to map matching ACL traffic to the designated pool.
The scenario requires using a pre-defined named pool of public IP addresses instead of a single interface.
3
Enable port multiplexing (PAT)
Append the 'overload' keyword at the end of the command.
Without 'overload', Cisco IOS configures standard dynamic NAT (1-to-1 translation), whereas PAT (many-to-one/many-to-few using layer 4 ports) explicitly requires 'overload'.

Anahtar Kavram

Port Address Translation (PAT) pool configuration using the overload keyword
Soru 330Soru →

An engineer configures a next-hop IPv4 static route on a Cisco router using the command `ip route 10.1.2.0 255.255.255.0 192.168.12.2`. Place the processing steps in the correct sequential order from first to last that the router performs when forwarding an incoming packet destined for 10.1.2.4510.1.2.45.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence for packet forwarding with a next-hop static route is: First, match the packet destination IP 10.1.2.4510.1.2.45 to the static route entry pointing to next-hop 192.168.12.2192.168.12.2. Second, perform a recursive lookup in the routing table for 192.168.12.2192.168.12.2 to find the outgoing interface. Third, look up the MAC address of 192.168.12.2192.168.12.2 in the ARP table. Fourth, encapsulate the packet into a Layer 2 frame and transmit it out the egress interface.
When a static route specifies only a next-hop IPv4 address (recursive static route), the router must first identify the static route via longest-prefix match. Next, it performs a recursive RIB lookup on the next-hop IP address to determine the exit interface. After identifying the exit interface, it performs an ARP table lookup to find the next-hop MAC address, and finally encapsulates and transmits the frame.

Adım Adım Çözüm

1
Evaluate incoming packet destination IP against routing table entries.
The destination address 10.1.2.4510.1.2.45 matches static route 10.1.2.0/2410.1.2.0/24 with next-hop 192.168.12.2192.168.12.2.
Routing decisions begin with a longest-prefix match lookup in the RIB.
2
Perform recursive routing lookup for next-hop IP address 192.168.12.2192.168.12.2.
The router identifies the directly connected network prefix and egress interface used to reach 192.168.12.2192.168.12.2.
Static routes configured solely with a next-hop IP require a recursive lookup to identify the exit interface.
3
Resolve Layer 2 destination hardware address via ARP cache lookup for 192.168.12.2192.168.12.2.
The target next-hop MAC address is retrieved for frame header construction.
Ethernet interfaces require the next-hop MAC address to format the data-link layer encapsulation.
4
Encapsulate IPv4 packet into Layer 2 Ethernet frame and send out the egress interface.
The packet is transmitted on the physical wire.
All forwarding requirements (interface and Layer 2 rewrite info) are complete.

Anahtar Kavram

IPv4 Static Route Recursive Lookup & Forwarding Process
Tahmini Süre:1m 30s
Soru 331Soru →

What prefix and prefix length parameter completes the Cisco IOS command to configure a default IPv6 static route pointing to next-hop address $2001:

\text{db8}:1::2$?

Aşağıdaki boşlukları doldurun

Router(config)# ipv6 route 2001:db8:1::2
Cevabı ve açıklamayı göster

Cevap

The correct notation to represent a default route in IPv6 static routing is ::/0.
In IPv6 static routing, ::/0 is the prefix notation for a default route, serving the same function as 0.0.0.0/0 in IPv4.

Adım Adım Çözüm

1
Identify the network prefix used to match all possible IPv6 destinations.
The default IPv6 route prefix is written as ::/0.
In IPv6 addressing, :: represents all zeros, and /0 indicates a prefix length of zero bits, matching any destination address.
2
Substitute the default prefix into the Cisco IOS IPv6 static routing command syntax.
The completed command is 'ipv6 route ::/0 2001:db8:1::2'.
The standard command syntax requires 'ipv6 route <destination-prefix/prefix-length> <next-hop-address>'.

Anahtar Kavram

IPv6 Default Static Route Configuration
Tahmini Süre:45s
Soru 332Soru →

A network engineer is configuring Rapid PVST+ on a Cisco Catalyst switch to force it to become the Root Bridge for VLAN 40. The engineer attempts to configure a custom bridge priority value using the Cisco IOS CLI command line syntax. Which command entry contains a valid bridge priority value that Cisco IOS will accept, and what total bridge priority value will the switch advertise in its outbound Spanning Tree Protocol BPDUs for VLAN 40?

Cevabı ve açıklamayı göster

Cevap: The command 'spanning-tree vlan 40 priority 4096' will be accepted, and the advertised total bridge priority will be 4136.

Cevap

The command 'spanning-tree vlan 40 priority 4096' will be accepted, and the advertised total bridge priority will be 4136.
In Cisco Rapid PVST+, the 16-bit priority portion of the 8-byte Bridge ID (BID) is divided into a 4-bit Bridge Priority and a 12-bit System ID Extension. Because only 4 bits are allocated to user configuration (24=162^4 = 16 levels), priority values in CLI commands must increase in steps of 4096 (4096×1=40964096 \times 1 = 4096). When the command 'spanning-tree vlan 40 priority 4096' is executed, Cisco IOS validates 40964096 as a valid base priority. During BPDU generation for VLAN 40, the switch adds the VLAN ID (4040) as the System ID Extension, resulting in a total priority value of 4096+40=41364096 + 40 = 4136.

Adım Adım Çözüm

1
Verify CLI input validation rules for Rapid PVST+ bridge priority
Cisco IOS requires configurable bridge priority values to be explicit multiples of 4096 (0,4096,8192,12288,…,614400, 4096, 8192, 12288, \dots, 61440).
The 16-bit Priority field in the Bridge ID (BID) uses the 4 most significant bits for configurable priority and the remaining 12 bits for the System ID Extension (VLAN ID).
2
Calculate the total advertised Bridge Priority field value
Base Priority (40964096) + System ID Extension (4040) = Total Priority (41364136).
Rapid PVST+ dynamically inserts the 12-bit VLAN ID into the System ID Extension field for per-VLAN spanning tree identification.

Anahtar Kavram

Rapid PVST+ Bridge ID Structure and System ID Extension Calculation
Soru 333Soru →

An administrator connects a switch access port to a user workstation without enabling Cisco PortFast. Place the standard IEEE 802.1D Spanning Tree Protocol (STP) port states in the chronological sequence that the interface transitions through from initial physical link up to active user data forwarding.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct chronological sequence of IEEE 802.1D STP port state transitions is: Blocking state, Listening state, Learning state, and Forwarding state.
In classic IEEE 802.1D Spanning Tree Protocol (STP), an edge port not configured with PortFast undergoes a strict 30-second convergence timer sequence: Blocking (initial loop prevention) -> Listening (15s, BPDU exchange and role selection) -> Learning (15s, MAC table population without data forwarding) -> Forwarding (active data packet processing).

Adım Adım Çözüm

1
Identify initial link state
Port enters Blocking state
Standard 802.1D STP defaults unconfigured edge ports to Blocking to safely prevent loops during initial topology evaluation.
2
Transition to neighbor discovery and role determination
Port enters Listening state for 15 seconds (Forward Delay)
BPDUs are transmitted and processed to elect root bridges and designate root/designated port roles.
3
Prepare Layer 2 forwarding tables
Port enters Learning state for 15 seconds (Forward Delay)
MAC addresses are learned from incoming frames to populate the CAM table, mitigating flooding when forwarding begins.
4
Complete convergence to operational status
Port enters Forwarding state
With topology determined and MAC table initialized, user frames are actively forwarded.

Anahtar Kavram

IEEE 802.1D STP Port State Transitions
Tahmini Süre:1m 15s
Soru 334Soru →

An administrator needs to enable Link Aggregation (LAG) on a Cisco Wireless LAN Controller (WLC) connected to an upstream switch stack. Place the configuration and operational steps in the correct chronological sequence from start to finish.

Öğeleri doğru sıraya koymak için sürükleyin

Cevabı ve açıklamayı göster

Cevap

The correct sequence begins with saving the WLC configuration, enabling LAG in the controller settings, saving and rebooting the WLC to apply the change, and finally configuring the connected switch ports as a static EtherChannel (mode on).
The sequence follows the standard Cisco procedure for turning on controller-wide Link Aggregation (LAG). First, current configuration state is saved. Second, LAG is enabled in the WLC settings menu. Third, the WLC configuration is saved and the controller is rebooted to apply the change. Fourth, the corresponding switch ports are configured into a static EtherChannel using 'channel-group mode on' to complete the physical and logical aggregation.

Adım Adım Çözüm

1
Save the existing WLC configuration
Establishes a baseline configuration state before initiating a system reboot
It is essential to safeguard existing controller configuration prior to changing structural hardware modes.
2
Enable LAG in WLC settings
Places the WLC into a pending LAG state
The controller feature knob for LAG must be explicitly enabled before hardware interface aggregation takes effect.
3
Save and reboot the WLC
The controller reboots with LAG operational across all physical distribution system ports
Enabling LAG on a Cisco WLC requires a reboot to reconfigure internal interface mappings.
4
Configure static EtherChannel on the upstream switch
The switch ports bundle into a single logical link matching the WLC LAG mode
Cisco WLC LAG requires static frame grouping ('mode on') on the switch side since WLCs do not support LACP or PAgP negotiation.

Anahtar Kavram

WLC Link Aggregation (LAG) configuration workflow and switch port requirements
Soru 335Soru →

Match each IPv6 prefix or address block on the left with its correct architectural scope and function on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

2000::/3
fe80::/10
fc00::/7
ff02::2

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

2000::/3 matches Global Unicast Address range reserved for publicly routable Internet communication; fe80::/10 matches Link-Local unicast prefix mandatory for single-segment neighbor communication; fc00::/7 matches Unique Local Address prefix used for private internal site routing; ff02::2 matches All-routers link-local multicast address targeting all routers on the segment.
Each IPv6 address prefix maps precisely to its RFC-defined scope: 2000::/3 is Global Unicast, fe80::/10 is Link-Local, fc00::/7 is Unique Local, and ff02::2 is the all-routers multicast group address.

Adım Adım Çözüm

1
Identify the primary block for Global Unicast Addresses (GUA)
2000::/3 encompasses all addresses from 2000:: through 3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff, which are globally routable.
IANA allocates GUA prefix blocks starting within the 2000::/3 range.
2
Identify the designated Link-Local unicast prefix scope
fe80::/10 defines the range fe80:: through febf:ffff:ffff:ffff:ffff:ffff:ffff:ffff used for intra-link communication.
IPv6 devices use link-local addresses for neighbor discovery and router solicitations.
3
Identify the private/internal IPv6 address range
fc00::/7 covers the block fc00:: through fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff for Unique Local Addresses.
ULAs provide non-globally routable addressing within private organizational boundaries.
4
Identify specific well-known IPv6 multicast group addresses
ff02::2 is the link-local scope multicast address received by all active routers on a network segment.
Multicast prefix ff00::/8 uses the scope indicator 2 (link-local) and group ID 2 (all routers).

Anahtar Kavram

IPv6 Address Scopes and Reserved Prefixes
Soru 336Soru →

When a Cisco router receives an IP packet, it evaluates several parameters to determine the best route to place into the routing decision process. Place the path selection criteria in the correct sequential order, from the primary (first evaluated) factor to the final tie-breaker factor.

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Cevabı ve açıklamayı göster

Cevap

The correct order of router decision criteria is: 1) Longest Prefix Match, 2) Administrative Distance, 3) Metric, 4) Equal-Cost Multi-Path.
Router forwarding decision logic evaluates parameters in a strict hierarchical order. First, Longest Prefix Match identifies the most specific network prefix for the destination IP address. If multiple routes exist with the exact same prefix length from different protocols, Administrative Distance breaks the tie by choosing the lower value. If multiple candidate routes come from the same routing protocol with identical prefix lengths, the Metric is used as the next tie-breaker. Finally, if prefix length, Administrative Distance, and metric are all identical, Equal-Cost Multi-Path load balancing is performed.

Adım Adım Çözüm

1
Determine primary routing lookup criteria
Longest Prefix Match is checked first.
Prefix specificity always takes precedence over AD and metric.
2
Evaluate tie-breaker between different routing protocols for the exact same prefix length
Administrative Distance is compared.
Lower AD indicates a more trustworthy routing source.
3
Evaluate tie-breaker within the same routing protocol
Metric is compared.
Lower metric indicates a lower internal routing protocol cost.
4
Handle identical tie-breaker results
Equal-Cost Multi-Path load balancing is applied.
When all parameters match identically, the router balances traffic across the equal routes.

Anahtar Kavram

Router Forwarding Decision Logic Sequence
Soru 337Soru →

A Cisco router receives an IP packet destined for 10.20.12.15010.20.12.150. Refer to the following routing table output:

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

Gateway of last resort is 10.1.1.1 to network 0.0.0.0

D 10.20.0.0/14 [90/2172416] via 192.168.1.2, GigabitEthernet0/1
O 10.20.12.0/22 [110/20] via 192.168.1.6, GigabitEthernet0/2
S 10.20.12.0/24 [1/0] via 192.168.1.10, GigabitEthernet0/3
O 10.20.12.128/25 [110/30] via 192.168.1.14, GigabitEthernet0/4
S* 0.0.0.0/0 [1/0] via 10.1.1.1, GigabitEthernet0/0

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

Cevabı ve açıklamayı göster

Cevap: 192.168.1.14

Cevap

The router forwards the packet to next-hop IP 192.168.1.14 because the route 10.20.12.128/25 has the longest prefix match for destination 10.20.12.150.
When forwarding IP packets, a Cisco router always prioritizes the route with the Longest Prefix Match (most specific subnet mask). The destination address 10.20.12.150 falls within the range 10.20.12.128 to 10.20.12.255 defined by 10.20.12.128/25. Because /25 is more specific than /24, /22, /14, or /0, the router uses this route, which forwards to next-hop 192.168.1.14.

Adım Adım Çözüm

1
Identify all candidate routes that encompass the destination IP address 10.20.12.150.
Candidate routes are 10.20.0.0/14, 10.20.12.0/22, 10.20.12.0/24, 10.20.12.128/25, and 0.0.0.0/0.
The router evaluates destination IP bit alignment against subnet masks of all known routes.
2
Compare the prefix lengths of all matching candidate routes.
Prefix lengths are /14, /22, /24, /25, and /0. The route 10.20.12.128/25 has the longest prefix mask (/25).
Routers use the Longest Prefix Match (LPM) logic first before considering Administrative Distance or Metric.
3
Select the next-hop IP associated with the longest prefix match route.
The route 10.20.12.128/25 points to next-hop 192.168.1.14.
Longest prefix match determines the exact routing entry used for forwarding.

Anahtar Kavram

Longest Prefix Match (LPM) precedence in IP forwarding decision logic.
Soru 338Soru →

A network engineer is configuring Virtual Router Redundancy Protocol (VRRP) on a router interface that has been assigned the physical IPv4 address 10.1.1.1/2410.1.1.1/24. The engineer enters the command `vrrp 1 ip 10.1.1.1`. Which statement correctly describes the operational result of configuring the physical interface IP address as the VRRP virtual IP address?

Cevabı ve açıklamayı göster

Cevap: VRRP accepts the configuration, allowing the router to become the IP address owner with a priority automatically set to 255.

Cevap

VRRP accepts the configuration, allowing the router to become the IP address owner with a priority automatically set to 255.
In VRRP, an engineer can assign the physical interface IP address as the virtual IP address. When this is done, the router becomes the IP address owner and its priority is automatically assigned as 255, making it the active Master router for that VRRP group.

Adım Adım Çözüm

1
Identify the protocol and command syntax specified in the scenario.
The scenario uses VRRP (`vrrp 1 ip 10.1.1.1`) where the virtual IP address matches the primary physical interface IP address (10.1.1.110.1.1.1).
Understanding protocol-specific rules regarding virtual IP address assignment is essential.
2
Evaluate VRRP operational rules for IP address ownership.
RFC 5798 / VRRP standards state that if a router's physical interface IP address is configured as the VRRP virtual IP address, that router becomes the IP address owner.
VRRP permits virtual IP reuse, unlike HSRP which enforces separate virtual IP addresses.
3
Determine the resulting priority value for the IP address owner.
The IP address owner in VRRP automatically receives the highest possible priority value of 255.
This guarantees that the owner router will always become the Master router when functional.

Anahtar Kavram

VRRP IP Address Ownership and Priority Assignment
Soru 339Soru →

A Cisco router receives an IPv4 packet destined for host 10.200.15.42. The router inspects its routing table and finds the following entry routes:

text
O 10.200.15.0/24 [110/20] via 172.16.1.1, GigabitEthernet0/0/1
S 10.200.0.0/16 [1/0] via 172.16.2.1, GigabitEthernet0/0/2
D 10.200.15.32/28 [90/307200] via 172.16.3.1, GigabitEthernet0/0/3
B 10.200.15.40/30 [200/0] via 172.16.4.1, GigabitEthernet0/0/4

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

Cevabı ve açıklamayı göster

Cevap: 172.16.4.1 via GigabitEthernet0/0/4 because the 10.200.15.40/30 route has the longest prefix match.

Cevap

The router forwards the packet to next-hop 172.16.4.1 via interface GigabitEthernet0/0/4 because the 10.200.15.40/30 prefix offers the longest prefix match.
When a router receives an IP packet, it compares the destination IP address (10.200.15.42) against all entries in its routing table. The matching entries cover the following ranges:
- 10.200.0.0/16 (/16)
- 10.200.15.0/24 (/24)
- 10.200.15.32/28 (/28: 10.200.15.32 to 10.200.15.47)
- 10.200.15.40/30 (/30: 10.200.15.40 to 10.200.15.43)

Because 10.200.15.42 falls within the /30 range, and /30 is the most specific prefix (longest prefix match), the router selects the entry pointing to 172.16.4.1 via GigabitEthernet0/0/4. Administrative Distance is not evaluated across different prefix lengths.

Adım Adım Çözüm

1
Identify all candidate routes in the routing table that encompass the destination IPv4 address 10.200.15.42.
Candidate routes are 10.200.0.0/16, 10.200.15.0/24, 10.200.15.32/28 (range 10.200.15.32–10.200.15.47), and 10.200.15.40/30 (range 10.200.15.40–10.200.15.43). All four entries match the destination address.
Before comparing routing metrics or administrative distance, the router identifies every route that includes the target IP address within its range.
2
Apply the Longest Prefix Match (LPM) rule to choose among matching entries.
Prefix lengths are /16, /24, /28, and /30. The /30 route has the longest mask length (30 set subnet bits).
Cisco IOS packet forwarding decision logic prioritizes prefix specificity above all other metrics, including Administrative Distance and routing protocol metrics.
3
Determine the next-hop IP and outgoing interface from the winning route entry.
The entry 10.200.15.40/30 points to next-hop 172.16.4.1 via GigabitEthernet0/0/4.
The router uses the next-hop parameters specified by the chosen LPM entry to perform Layer 2 frame encapsulation and egress transmission.

Anahtar Kavram

Longest Prefix Match (LPM) Rule
Tahmini Süre:1m 15s
Soru 340Soru →

A network administrator is configuring edge ports on a Cisco Catalyst switch connected to user workstations. Which two statements describe the operational benefits and behaviors when Cisco PortFast is enabled on an access interface? (Select TWO.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The interface bypasses the Listening and Learning STP states, transitioning directly to Forwarding upon link connection.; Link state changes on the PortFast-enabled port do not cause the switch to generate Topology Change Notifications (TCNs).

Cevap

The correct benefits are that the interface bypasses the Listening and Learning STP states to transition directly to Forwarding, and link state changes on the port do not cause the switch to generate Topology Change Notifications (TCNs).
PortFast provides two primary operational advantages on end-user access ports: first, it bypasses the Listening (15s) and Learning (15s) states to move immediately into Forwarding state when a link comes online. Second, it suppresses Topology Change Notification (TCN) messages when the port changes status, preventing unnecessary MAC table aging throughout the campus network.

Adım Adım Çözüm

1
Identify the main objective of configuring Cisco PortFast on switch ports.
PortFast is intended strictly for access ports connected to end-user devices such as PCs, printers, or IP phones.
End-user devices do not run Spanning Tree Protocol or form Layer 2 redundant loops under normal topology conditions.
2
Analyze state transition behavior for PortFast-enabled ports.
Upon link activation, the port skips the 15-second Listening and 15-second Learning timer delays and immediately enters Forwarding.
Eliminating this 30-second delay ensures client hosts do not experience address assignment timeouts during initial network startup.
3
Evaluate the impact of PortFast on STP topology updates across the network.
Port transitions on PortFast interfaces are prevented from triggering Topology Change Notifications (TCNs) sent toward the Root Bridge.
Suppressing TCNs avoids unnecessary flushing of MAC address tables across the entire switching domain when host ports connect or disconnect.

Anahtar Kavram

STP PortFast Benefits and Operational Trait
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