Examkin

All practice questions

1987 questions

All types1,987Multiple choice1,020Multiple select452Numeric18Matching229Ordering203Fill in the blank22Short answer43
Question 841Question →

An engineer is troubleshooting a switch port running classic 802.1D Spanning Tree Protocol (STP) that connects to an access host. The current interface state is shown below:

text
Switch# show spanning-tree interface GigabitEthernet 0/1
Vlan Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0010 Desg LRN 4 128.1 P2p

If the network administrator configures `spanning-tree portfast` on interface GigabitEthernet 0/1 and the link subsequently flaps, which statement accurately describes the operational state transitions and spanning-tree behaviors of this interface?

Show answer & explanation

Answer: The interface immediately transitions upon link-up from Blocking directly to Forwarding, skipping Listening and Learning, and it does not trigger a Topology Change Notification (TCN) when the link flaps.

Answer

The interface immediately transitions upon link-up from Blocking directly to Forwarding, skipping Listening and Learning, and it does not trigger a Topology Change Notification (TCN) when the link flaps.
Enabling Cisco PortFast on an access interface causes it to transition directly from Blocking to Forwarding immediately upon link up, completely bypassing the 15-second Listening and 15-second Learning states. In addition, link flaps on PortFast-enabled ports do not send Topology Change Notifications (TCNs) to the Root Bridge, avoiding global MAC address table aging flushes.

Step-by-Step Solution

1
Analyze the initial interface output status.
The command output shows interface GigabitEthernet 0/1 in the Designated role and LRN (Learning) state.
Standard 802.1D STP transitions through Blocking (20s max age) -> Listening (15s forward delay) -> Learning (15s forward delay) -> Forwarding (total convergence delay of 30-50 seconds).
2
Evaluate the impact of enabling Cisco PortFast on an access interface.
PortFast bypasses the Listening and Learning states, placing the port into Forwarding immediately when link-up occurs.
End-user hosts (workstations, servers, printers) do not create Layer 2 loops and require rapid link activation to prevent DHCP lease timeouts or PXE boot failures.
3
Determine the Topology Change Notification (TCN) behavior associated with PortFast.
Link up/down events on PortFast-enabled ports do not generate TCNs.
Preventing TCN generation eliminates unnecessary MAC address table timer reductions (aging down to forward delay) across the switches in the STP domain whenever end-user PCs reboot or disconnect.

Key Concept

STP Port States and PortFast Benefits
Estimated Time:1m 30s
Question 842Question →

A network administrator is configuring interface GigabitEthernet0/1 on a Cisco Catalyst switch to connect a single end-user computer. The interface needs to be explicitly configured as an access port and assigned to VLAN 10. Which two Cisco IOS commands must be entered in interface configuration mode to complete this task?

Select all that apply

Show answer & explanation

Answer: switchport mode access; switchport access vlan 10

Answer

The correct commands are 'switchport mode access' to define the operational mode as an access port, and 'switchport access vlan 10' to assign the access port to VLAN 10.
To properly configure an access port on a Cisco Catalyst switch, the administrator must define the port operational mode using 'switchport mode access' and specify its VLAN association using 'switchport access vlan 10'.

Step-by-Step Solution

1
Set the switch port mode to access.
Interface is forced into static non-trunking (access) mode.
Ensures the port will not negotiate trunking via DTP and acts as a standard access port.
2
Assign the access port to the target VLAN.
Interface is placed into VLAN 10.
Associates untagged frames received on this access port with VLAN 10.

Key Concept

Cisco IOS VLAN Access Port Configuration
Estimated Time:45s
Question 843Question →

An engineer is analyzing legacy IEEE 802.1D Spanning Tree Protocol (STP) behavior on a Cisco switch interface that is configured without PortFast. Place the following STP port states in chronological order, starting from link initialization and ending when the interface reaches active user data transmission.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological order of classic IEEE 802.1D STP port states during port initialization is Blocking, Listening, Learning, and Forwarding.
Standard IEEE 802.1D STP port state convergence transitions sequentially through Blocking (loop prevention / BPDU listening) -> Listening (BPDU transmission/reception, topology role determination) -> Learning (MAC address table population without frame forwarding) -> Forwarding (full data frame forwarding and continuous learning).

Step-by-Step Solution

1
Identify the initial state assigned to prevent immediate switching loops upon link UP.
The interface starts in the Blocking state where data frames are dropped and MAC addresses are not learned, but incoming BPDUs are evaluated.
802.1D STP defaults to a loop-prevention state to listen for existing network bridge topology.
2
Determine the state where active STP participation and BPDU transmission begin.
The port transitions to the Listening state for 15 seconds (Forward Delay), sending and receiving BPDUs to elect the root bridge and establish port roles.
In Listening, the switch establishes topology structure without yet accepting host MAC entries.
3
Identify the state designed to populate layer 2 tables prior to passing payload traffic.
The port moves to the Learning state for an additional 15 seconds (Forward Delay), reading source MAC addresses from frame headers without forwarding frames.
Pre-building the MAC address table minimizes unicast flooding once frame forwarding is enabled.
4
Identify the ultimate operational state achieved upon timer completion.
The port enters the Forwarding state, enabling full bidirectional user traffic forwarding alongside ongoing BPDU processing and MAC learning.
The port has passed all convergence checks over the 30-second convergence window.

Key Concept

Classic IEEE 802.1D STP Port State Transition Sequence
Question 844Question →

A network engineer is configuring a routed (Layer 3) EtherChannel between two switches using LACP. The engineer issued the `no switchport` command on physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2 before assigning them to channel group 1 with mode `active`. However, the bundle fails to pass routed traffic. Upon executing `show etherchannel summary`, the output displays:

text
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SD) LACP Gi0/1(I) Gi0/2(I)

Which administrative action will resolve this issue and bring the Layer 3 EtherChannel into an operational state?

Show answer & explanation

Answer: Issue the `no switchport` command on the logical Port-Channel 1 interface.

Answer

Issue the `no switchport` command on the logical Port-Channel 1 interface.
The `show etherchannel summary` command output displays `Po1(SD)`, where `S` signifies Layer 2 and `D` signifies Down. Because the physical member interfaces were configured with `no switchport`, they are operating as Layer 3 ports. LACP prevents ports from bundling if there is a mismatch between the physical member ports and the logical port-channel interface mode. Converting the Port-Channel 1 interface to Layer 3 using `no switchport` resolves the configuration mismatch and enables the LACP bundle to become operational (`Po1(RU)` or `Po1(SU)` depending on code version definitions).

Step-by-Step Solution

1
Analyze the flags in the `show etherchannel summary` output.
Flag `S` on `Po1(SD)` indicates Layer 2 operational mode, and flag `D` indicates Down. Flags `(I)` on member ports indicate Stand-alone state.
The physical ports were configured as routed ports (`no switchport`), but the logical Port-Channel interface retained its default Layer 2 switchport property.
2
Identify the underlying compatibility requirement for EtherChannel aggregation.
All physical member interfaces and the parent Port-Channel interface must share matching operational parameters, including Layer 2 vs. Layer 3 mode.
LACP will suspend member ports or keep them stand-alone if there is a Layer 2 / Layer 3 mode mismatch with the logical port-channel.
3
Determine the corrective CLI command on the logical interface.
Executing `interface Port-channel 1` followed by `no switchport` converts the logical interface to Layer 3.
Aligning the logical interface mode to Layer 3 allows LACP to bundle Gi0/1 and Gi0/2 into Po1, changing the flags to `SU` (Layer 3, in Use) and member port flags to `P` (bundled in port-channel).

Key Concept

Layer 3 EtherChannel Configuration and Operability Flags
Estimated Time:2m 0s
Question 845Question →

An enterprise network team is troubleshooting an LACP-based routed EtherChannel between Switch-1 and Switch-2.

Switch-1 configuration snippet:
interface range GigabitEthernet0/1 - 2
no switchport
channel-group 12 mode active
!
interface Port-channel 12
no switchport
ip address 10.1.12.1 255.255.255.252

Switch-2 command output:
# show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby S - Layer2
R - Layer3 U - in use
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
12 Po12(SD) LACP Gi0/1(I) Gi0/2(I)

Which configuration change on Switch-2 will successfully establish the Layer 3 EtherChannel and bring Port-channel 12 to the operational Layer 3 state (RU)?

Show answer & explanation

Answer: Configure 'no switchport' and 'channel-group 12 mode passive' on physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2, then assign the IP address under interface Port-channel 12.

Answer

The correct action is to configure 'no switchport' and 'channel-group 12 mode passive' on physical interfaces GigabitEthernet0/1 and GigabitEthernet0/2, and assign the IP address under interface Port-channel 12.
To transition Port-channel 12 on Switch-2 from (SD) Layer 2 Down to (RU) Layer 3 In-Use, the physical member interfaces (Gi0/1 and Gi0/2) must have switchport functionality disabled via 'no switchport'. LACP dynamic negotiation requires compatible modes across both switches; since Switch-1 is configured in 'active' mode, Switch-2 can use either 'active' or 'passive' mode. Lastly, IP addressing in a Layer 3 EtherChannel must be assigned directly to the Port-channel 12 logical interface rather than to the individual member interfaces.

Step-by-Step Solution

1
Analyze the output of 'show etherchannel summary' on Switch-2.
Port-channel 12 shows flag 'S' (Layer 2) and 'D' (Down), while physical interfaces show 'I' (Stand-alone). Switch-1 is configured as Layer 3 ('R').
The flags indicate a Layer mismatch (Layer 2 on Switch-2 vs Layer 3 on Switch-1) and independent member states due to incomplete Layer 3/LACP setup.
2
Determine Layer 3 EtherChannel requirements for member interfaces.
Member interfaces must be routed ports using the 'no switchport' command prior to or matching port-channel settings.
EtherChannel member interfaces must match Layer 2 or Layer 3 properties to form an operational bundle.
3
Verify LACP mode compatibility.
Switch-1 is set to 'active'. Switch-2 must be set to 'active' or 'passive'.
LACP requires at least one side to be in active mode to initiate link aggregation control protocol negotiation.
4
Verify Layer 3 IP address placement.
The IP address must be assigned to interface Port-channel 12, not to individual physical interfaces.
In a routed EtherChannel, the port-channel interface acts as the single logical Layer 3 routing point.

Key Concept

Layer 3 EtherChannel LACP Negotiation and Troubleshooting
Estimated Time:3m 0s
Question 846Question →

A switch port running standard IEEE 802.1D Spanning Tree Protocol (STP) detects an active connection to an end device. Arrange the STP port states in the correct sequential order from initial physical link detection to fully active data frame forwarding.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential progression of 802.1D STP port states is: Blocking State, Listening State, Learning State, and Forwarding State.
Under standard IEEE 802.1D, a newly connected port progresses through four distinct states to ensure network loops do not form: Blocking (drops data, listens for BPDUs), Listening (discards data, sends/receives BPDUs, no MAC learning), Learning (discards data, learns MAC addresses), and finally Forwarding (forwards data frames normally).

Step-by-Step Solution

1
Identify the initial state upon link up.
The port starts in the Blocking state to avoid creating temporary switching loops while BPDU information is evaluated.
802.1D requires all non-designated/non-root ports or newly activated ports to block user traffic initially.
2
Determine the transition following BPDU analysis.
The port transitions to the Listening state for the duration of the Forward Delay timer (15 seconds).
During Listening, the port sends and receives BPDUs to elect root bridges and assign port roles without forwarding traffic or learning MAC addresses.
3
Determine the step after topology role determination.
The port enters the Learning state for a second Forward Delay timer interval (15 seconds).
Learning allows the switch to build its MAC address table from source MACs in incoming frames to minimize flooding when forwarding begins.
4
Identify the final operational state.
The port reaches the Forwarding state.
Once the learning phase expires without topology conflicts, the interface fully forwards user data frames and processes BPDUs.

Key Concept

802.1D Spanning Tree Protocol Port State Transitions
Estimated Time:45s
Question 847Question →

A network administrator is setting up out-of-band administrative access for a newly deployed Cisco Wireless LAN Controller (WLC). The design requires isolating administrative management traffic (GUI/SSH) from AP CAPWAP tunnels and user data traffic by utilizing the dedicated physical Service Port on the WLC. Which operational characteristic correctly describes the behavior and network configuration of the WLC Service Port?

Show answer & explanation

Answer: It operates strictly out-of-band and uses an independent routing configuration separate from the WLC data plane dynamic and management interfaces.

Answer

The WLC Service Port operates strictly out-of-band and uses an independent routing configuration separate from the WLC data plane dynamic and management interfaces.
The correct answer highlights that the Cisco WLC Service Port is a dedicated out-of-band management interface. It is physically separate from the distribution system ports, operates in its own routing domain, and is reserved for administrative GUI/SSH management, system recovery, and maintenance without handling CAPWAP or client data traffic.

Step-by-Step Solution

1
Identify the primary functional role of the Cisco WLC Service Port.
The Service Port is a dedicated 10/100/1000 Ethernet interface designed for out-of-band management, system recovery, and initial setup.
Out-of-band management separates administrative control plane traffic from data plane and wireless infrastructure traffic.
2
Evaluate how traffic routing and connectivity differ between the Service Port and in-band interfaces (Management/Dynamic).
The Service Port maintains its own static routing gateway configuration and does not pass CAPWAP, client data, or dynamic interface traffic.
This physical and logical isolation ensures management access remains functional even during heavy data plane saturation or network outages.

Key Concept

Cisco WLC Service Port vs. In-Band Management Interfaces
Estimated Time:1m 30s
Question 848Question →

A network administrator executes the command `show interface GigabitEthernet0/0` on a Cisco router and notes a MAC address of `a1b2.c3d4.e5f6`. The interface is then configured with the command `ipv6 address 2001:db8:1111:2222::/64 eui-64`. Which IPv6 global unicast address will be generated on this interface?

Show answer & explanation

Answer: 2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6

Answer

2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6
Generating an IPv6 EUI-64 interface identifier requires splitting the 48-bit MAC address (a1:b2:c3:d4:e5:f6) into two 24-bit halves, inserting FFFE in the middle (a1b2:c3ff:fed4:e5f6), and flipping the 7th bit (Universal/Local bit) of the first byte. Converting 0xa1 (10100001 in binary) to invert the 7th bit yields 0xa3 (10100011 in binary). Combining the prefix 2001:db8:1111:2222::/64 with the modified interface ID gives 2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6.

Step-by-Step Solution

1
Split MAC address into OUI and NIC identifier halves
OUI portion is a1:b2:c3 and NIC portion is d4:e5:f6
EUI-64 insertion occurs directly between the 24-bit OUI and the 24-bit device identifier.
2
Insert the 16-bit hex value FFFE between the two halves
a1b2:c3ff:fed4:e5f6
EUI-64 expands a 48-bit MAC address into a 64-bit interface identifier by adding 0xFFFE.
3
Invert the 7th bit (Universal/Local bit) of the first byte (0xa1)
0xa1 in binary is 10100001. Inverting the 7th bit yields 10100011, which is 0xa3.
IEEE EUI-64 standard requires flipping the Universal/Local (U/L) bit so that 0 (universal) becomes 1 (locally administered scope for auto-configured interfaces).
4
Combine configured /64 prefix with generated 64-bit interface ID
2001:db8:1111:2222:a3b2:c3ff:fed4:e5f6
The prefix 2001:db8:1111:2222::/64 forms the first 64 bits and the modified EUI-64 ID forms the last 64 bits.

Key Concept

EUI-64 Interface Identifier Generation
Estimated Time:1m 30s
Question 849Question →

Two Cisco Catalyst switches are connected using four physical Ethernet links intended for a high-capacity trunk bundle. The interfaces on Switch-1 are configured with `channel-group 5 mode active`, while the interfaces on Switch-2 are configured with `channel-group 5 mode passive`. After connecting the cables, three of the four links bundle successfully into `Port-channel 5`, but interface `GigabitEthernet0/1` on Switch-1 remains in an Independent (`I`) operational state. What is the primary cause of this member interface failing to join the active LACP EtherChannel?

Show answer & explanation

Answer: The interface has an operational speed or duplex setting that does not match the other physical member interfaces in the bundle.

Answer

The physical interface has an operational speed or duplex setting that does not match the other physical member interfaces in the bundle.
EtherChannel member interfaces must be configured identically regarding speed, duplex, media type, VLAN range, and trunking mode. If a single interface has a mismatched operational speed or duplex setting (e.g., auto-negotiated to 100/full instead of 1000/full), LACP consistency checks will fail for that port. Cisco IOS will flag the interface as Independent ('I') in the show etherchannel summary output, keeping it operating standalone outside the bundle while the matching ports form the EtherChannel.

Step-by-Step Solution

1
Analyze the LACP negotiation mode compatibility between Switch-1 and Switch-2.
Switch-1 is set to 'active' and Switch-2 is set to 'passive'. Active-to-passive is a valid LACP negotiation combination, so mode mismatch between switches is not the issue.
LACP active mode actively sends LACPDU packets, while passive mode responds to incoming LACPDUs.
2
Identify mandatory prerequisite physical interface matching parameters for EtherChannel member ports.
All member ports in an EtherChannel bundle must match speed, duplex, interface mode (access/trunk), native VLAN, and allowed VLANs.
If any individual physical port has a mismatched operational attribute (such as 100 Mbps when others are 1 Gbps), Cisco IOS prevents that port from joining the bundle to protect against frame misordering or forwarding loops.
3
Interpret the 'I' (Independent) flag in 'show etherchannel summary' output.
The 'I' flag indicates that the port is operating standalone (independently) because it failed EtherChannel consistency checks or negotiation.
Speed/duplex mismatch on that specific interface causes it to drop out of the logical bundle while remaining active as a standalone port.

Key Concept

EtherChannel Physical Interface Prerequisites & LACP Verification
Estimated Time:1m 15s
Question 850Question →

Refer to the following routing table output from a Cisco router:

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

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 4 subnets, 3 masks
O 10.1.0.0/16 [110/20] via 192.168.1.2, 00:05:12, GigabitEthernet0/0
D 10.1.4.0/22 [90/307200] via 192.168.1.6, 00:12:33, GigabitEthernet0/1
S 10.1.4.0/24 [1/0] via 192.168.1.10, 01:45:00, GigabitEthernet0/2
O 10.1.4.128/25 [110/10] via 192.168.1.14, 00:02:15, GigabitEthernet0/3

A packet arrives at the router with a destination IP address of 10.1.4.13010.1.4.130. Which exit interface will the router use to forward this packet?

Show answer & explanation

Answer: GigabitEthernet0/3, because the route to 10.1.4.128/25 has the longest matching prefix length for the destination IP address.

Answer

The router forwards the packet out interface GigabitEthernet0/3 because 10.1.4.128/25 is the longest prefix match for destination 10.1.4.130.
When a router receives an IP packet, it compares the destination IP address against all entries in its routing table. The fundamental rule of IP route selection is Longest Prefix Match (LPM). Since 10.1.4.130 matches 10.1.4.128/25 (/25 bit match), 10.1.4.0/24 (/24 bit match), 10.1.4.0/22 (/22 bit match), and 10.1.0.0/16 (/16 bit match), the router selects 10.1.4.128/25 because /25 is the longest (most specific) prefix length. Consequently, traffic is forwarded via GigabitEthernet0/3.

Step-by-Step Solution

1
Identify candidate routes matching destination IP 10.1.4.130.
The candidate routes are: 10.1.0.0/16, 10.1.4.0/22, 10.1.4.0/24, and 10.1.4.128/25.
All four routes contain IP address 10.1.4.130 within their range.
2
Determine the prefix length for each matching candidate route.
Prefix lengths are /16, /22, /24, and /25.
Longest Prefix Match (LPM) rule dictates that the route with the most specific subnet mask (highest prefix number) is selected first.
3
Select the route with the longest prefix match.
10.1.4.128/25 (/25) is the longest match, which forwards out GigabitEthernet0/3.
Administrative Distance (AD) and metric are ignored when prefix lengths differ among candidate routes.

Key Concept

Router Forwarding Decision Logic (Longest Prefix Match precedence over Administrative Distance and Metric)
Question 851Question →

A network administrator is designing an IPv4 addressing plan for a new office department. The department requires static host IP assignments for 61 client workstations, 1 default gateway router interface, and 1 network printer, requiring a total of 63 active host IP addresses. Which subnet mask provides the most efficient address space utilization while satisfying all required host addresses?

Show answer & explanation

Answer: 255.255.255.128255.255.255.128

Answer

The subnet mask 255.255.255.128255.255.255.128 (corresponding to a /25/25 prefix) is the most efficient subnet mask that accommodates 63 host IP addresses.
To support 63 active host interfaces, the subnet must provide at least 63 usable IPv4 addresses. Using 6 host bits yields 26−2=622^6 - 2 = 62 usable addresses, which falls 1 short. Therefore, 7 host bits are required (27−2=1262^7 - 2 = 126 usable addresses). A subnet with 7 host bits leaves 25 prefix bits (32−7=2532 - 7 = 25), corresponding to the dotted-decimal subnet mask 255.255.255.128255.255.255.128. This is the smallest subnet that satisfies the requirement without wasting excessive IP addresses.

Step-by-Step Solution

1
Determine total required host IP addresses
61 workstations+1 gateway+1 printer=63 usable host IP addresses61 \text{ workstations} + 1 \text{ gateway} + 1 \text{ printer} = 63 \text{ usable host IP addresses}
Every device and gateway interface requiring an IP address counts toward the total host capacity.
2
Calculate required host bits using the usable host capacity formula 2H−2≥632^H - 2 \ge 63
For H=6H = 6: 26−2=622^6 - 2 = 62 usable addresses (insufficient). For H=7H = 7: 27−2=1262^7 - 2 = 126 usable addresses (sufficient).
Two IP addresses in every subnet are reserved for the network ID and broadcast address.
3
Derive prefix length and dotted-decimal subnet mask
Prefix length =32−7=/25= 32 - 7 = /25, which converts to 255.255.255.128255.255.255.128
Subtracting 7 host bits from 32 total IPv4 bits leaves 25 network bits.

Key Concept

Usable IPv4 Host Address Calculation (2H−22^H - 2) and Subnet Mask Derivation
Question 852Question →

A network engineer is evaluating the Rapid PVST+ topology operational mechanics across a enterprise LAN segment. A switch has multiple active connections to adjacent switches and redundant interswitch links. Which two statements correctly describe Rapid PVST+ port role operations and behaviors in this environment? (Select two.)

Select all that apply

Show answer & explanation

Answer: An Alternate port receives BPDUs from a neighbor switch, provides an alternate path to the root bridge, and remains in the Discarding state.; A Backup port receives BPDUs originated by its own local switch over a shared collision domain or redundant link to the same segment and remains in the Discarding state.

Answer

The correct statements are that an Alternate port receives BPDUs from a neighbor switch to provide an alternate path toward the root bridge in the Discarding state, and a Backup port receives BPDUs sent by its own switch to provide redundancy for a Designated Port on the same collision domain.
In Rapid PVST+ (IEEE 802.1w implementation in Cisco switches), an Alternate port receives BPDUs from other switches and stands by to replace the Root Port if the active path to the root bridge fails. A Backup port receives BPDUs transmitted by its own switch over a shared media connection and stands by to replace the Designated Port for that specific segment. Both roles maintain a Discarding state to prevent Layer 2 loops.

Step-by-Step Solution

1
Analyze Alternate Port Role
Identified that an Alternate port receives BPDUs from other switches and acts as a standby path to the Root Bridge.
Rapid PVST+ defines Alternate ports to take over immediately if the primary Root Port loses connectivity to the root bridge.
2
Analyze Backup Port Role
Identified that a Backup port receives its own switch's BPDUs on a shared or redundant connection to the same network segment.
A Backup port backs up a local Designated Port on the same LAN segment when multiple interfaces from a single switch connect to the same shared collision domain.
3
Evaluate Distractors and Misconfigurations
Eliminated incorrect assertions regarding role substitution and PortFast trunk misapplications.
Alternate ports back up Root Ports (not Designated Ports), and PortFast is intended for edge host ports, not for bypassing Backup port role logic on interswitch links.

Key Concept

Rapid PVST+ Port Roles (Root, Designated, Alternate, Backup) and Operational States
Question 853Question →

A network engineer is configuring Port Address Translation (PAT) on a Cisco IOS router using an IP address pool. Access Control List 10 matches internal private IPv4 addresses, and the NAT pool is named `OUTSIDE_POOL`. To allow multiple internal hosts to share the addresses in `OUTSIDE_POOL` by multiplexing Layer 4 port numbers, which single keyword must be appended to the end of the `ip nat inside source list 10 pool OUTSIDE_POOL` command?

Show answer & explanation

Answer: overload; the overload keyword

Answer

overload
Appending the keyword `overload` to the `ip nat inside source list <acl> pool <pool_name>` command enables Port Address Translation (PAT). This allows Cisco IOS to translate both IP addresses and transport layer port numbers, enabling many internal private IP addresses to share public IP addresses in the pool.

Step-by-Step Solution

1
Identify the requirement for Port Address Translation (PAT) using an IP address pool.
Standard dynamic NAT assigns public IP addresses to private IP addresses on a one-to-one basis.
Without port tracking, dynamic pool NAT runs out of available public IPv4 addresses when internal hosts exceed the pool size.
2
Determine the necessary Cisco IOS command modifier to enable port multiplexing.
Appending the keyword `overload` instructs the router to track transport-layer port numbers (PAT).
The `overload` keyword enables multiple internal sockets to share pool addresses simultaneously.

Key Concept

Inside Source Port Address Translation (PAT) Pool-based Configuration
Estimated Time:1m 0s
Question 854Question →

A network administrator executes the command `show ip ospf interface gigabitethernet 0/0` on two interconnecting routers to troubleshoot an OSPF neighbor issue.

Output from Router R1:
text
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.1.12.1/24, Area 0
Process ID 10, Router ID 1.1.1.1, Network Type BROADCAST
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Output from Router R2:
text
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.1.12.2/24, Area 1
Process ID 20, Router ID 2.2.2.2, Network Type BROADCAST
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Which condition is preventing R1 and R2 from establishing an OSPF neighbor adjacency?

Show answer & explanation

Answer: The OSPF Area IDs configured on the connected interfaces do not match.

Answer

The OSPF Area IDs configured on the connected interfaces do not match.
For two OSPF routers to establish a neighbor adjacency across a direct link, several key parameters in their exchanged Hello packets must match. One mandatory matching parameter is the Area ID. Because Router R1 is configured in Area 0 and Router R2 is configured in Area 1 on their interconnecting interfaces, the routers will discard each other's Hello packets and remain in the DOWN state.

Step-by-Step Solution

1
Inspect the CLI output for interface parameters sent in OSPF Hello packets.
Router R1 has interface GigabitEthernet0/0 assigned to Area 0, while Router R2 has interface GigabitEthernet0/0 assigned to Area 1.
For OSPF neighbors to form an adjacency over a common link, the Area ID field in their exchanged Hello packets must match exactly.
2
Verify other OSPF Hello packet parameters for compatibility.
Both routers share identical IP subnets (10.1.12.0/24) and matching timers (Hello 10, Dead 40). Both have unique Router IDs (1.1.1.1 and 2.2.2.2).
Process IDs (10 vs 20) are locally significant and do not affect neighbor relationships across a link.

Key Concept

OSPF Neighbor Adjacency Requirements
Estimated Time:1m 15s
Question 855Question →

A network administrator needs to configure a floating static default route on a Cisco IOS router to serve as a backup to an existing OSPF-learned default route (Administrative Distance of 110). Place the operational steps in the correct sequential order to configure, validate normal operation, and verify failover behavior of this backup route.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct operational sequence begins by analyzing the primary protocol AD (110), navigating to global configuration mode, defining the floating static default route with a higher AD value (120), verifying that the route remains inactive in the routing table during normal operations, and finally testing link failover to confirm RIB insertion.
The workflow follows standard Cisco IOS network administration practices: planning parameters (AD selection), configuration entry, syntax application, baseline verification (confirming inactivity while primary is up), and failover validation (confirming activation when primary drops).

Step-by-Step Solution

1
Determine the primary route's Administrative Distance.
Identified OSPF AD as 110, requiring a floating static route AD > 110 (e.g., 120).
Floating static routes rely on a higher AD than the active routing source so they remain inactive until the primary route fails.
2
Access configuration mode.
Router prompt changes to `Router(config)#`.
Cisco IOS static route creation requires global configuration access.
3
Apply the static route configuration.
Configured `ip route 0.0.0.0 0.0.0.0 203.0.113.2 120`.
Defines a default route (`0.0.0.0 0.0.0.0`) pointing to next-hop `203.0.113.2` with an AD argument of `120`.
4
Verify initial routing table state.
Confirmed OSPF route is active in RIB and static route is absent.
Ensures the floating route does not preempt the primary dynamic path while the primary path is healthy.
5
Test path failover under fault conditions.
Static route `S* 0.0.0.0/0 [120/0] via 203.0.113.2` appears in `show ip route` output upon primary interface shutdown.
Validates proper failover functionality when the primary route is removed from the routing table.

Key Concept

Floating Static Route Lifecycle and Failover Validation
Estimated Time:2m 0s
Question 856Question →

An engineer is configuring a backup link on router R2 to reach the internal network 10.50.0.0/1610.50.0.0/16. The primary path is currently learned dynamically via OSPF, which has a default administrative distance of 110. Which Cisco IOS command correctly configures a floating static route that remains inactive unless the primary OSPF route fails?

Show answer & explanation

Answer: ip route 10.50.0.0 255.255.0.0 172.16.12.2 120

Answer

The command 'ip route 10.50.0.0 255.255.0.0 172.16.12.2 120' correctly configures the floating static route.
A floating static route acts as a secondary path that is installed into the routing table only when the primary path fails. To achieve this behavior, the static route must be configured with an Administrative Distance (AD) higher than that of the primary routing protocol. Since OSPF has a default AD of 110, setting the static route AD to 120 ensures it stays in reserve.

Step-by-Step Solution

1
Identify the primary route's Administrative Distance (AD)
OSPF has a default AD of 110.
Floating static routes must have an AD strictly greater than the primary route's AD to remain hidden in the routing table until the primary path drops.
2
Verify Cisco IOS IPv4 static routing syntax
The correct format is 'ip route <destination-network> <subnet-mask> <next-hop-ip> [distance]'.
Standard subnet masks (dotted-decimal) are mandatory in Cisco IOS static routing syntax.
3
Select the option with an AD greater than 110 and proper subnet mask syntax
The command specifying an AD of 120 with mask 255.255.0.0 meets both requirements.
An AD of 120 ensures the static route is kept in backup state while OSPF is active.

Key Concept

Floating Static Route Administrative Distance Selection
Question 857Question →

An enterprise network team is deploying a virtualized data center infrastructure to support high-performance database workloads. The design requires a hypervisor deployment that operates directly on bare-metal server hardware without relying on an underlying host operating system to maximize resource efficiency and reduce overhead. Which hypervisor architecture meets these requirements, and what is its primary operational characteristics?

Show answer & explanation

Answer: A Type 1 hypervisor, which installs directly on the bare-metal hardware and manages guest operating systems directly.

Answer

A Type 1 hypervisor, which installs directly on the bare-metal hardware and manages guest operating systems directly.
The correct option correctly identifies a Type 1 hypervisor, also known as a bare-metal hypervisor. It runs directly on host server hardware, giving guest virtual machines direct access to compute and hardware resources while minimizing performance overhead.

Step-by-Step Solution

1
Analyze the operational requirements provided in the scenario.
The requirements demand a hypervisor that runs directly on server hardware (bare-metal) without an underlying host operating system to eliminate unnecessary latency and OS overhead.
Enterprise virtualized server environments hosting high-performance workloads require direct hardware abstraction and direct access to CPU, memory, and storage.
2
Distinguish between hypervisor types and network device roles.
Type 1 (bare-metal) hypervisors sit directly on host hardware. Type 2 (hosted) hypervisors require a host OS. Switches and discovery protocols handle network traffic forwarding and discovery, not host server virtualization.
Understanding component roles ensures selecting the architecture designed for bare-metal virtualization.

Key Concept

Hypervisor Architecture Types and Roles (Type 1 vs. Type 2)
Estimated Time:1m 30s
Question 858Question →

An enterprise network engineer is designing a branch office infrastructure with three specific requirements:
1. Virtualized server workloads must run directly on bare-metal hardware without an intermediate operating system layer.
2. Local VLAN broadcast domains must be segmented and routed at hardware wire speed using specialized Application-Specific Integrated Circuits (ASICs).
3. Wireless Access Points (APs) managed by a centralized Wireless LAN Controller (WLC) must continue switching local client traffic locally if the WAN connection to the central controller fails.

Which combination of network component operational roles and architecture satisfies all of these requirements?

Show answer & explanation

Answer: Deploy Type 1 hypervisors on server hardware, perform inter-VLAN routing using Layer 3 switches, and configure lightweight APs in FlexConnect mode.

Answer

Deploy Type 1 hypervisors on server hardware, perform inter-VLAN routing using Layer 3 switches, and configure lightweight APs in FlexConnect mode.
The correct selection combines Type 1 bare-metal hypervisors (which run directly on physical hardware), Layer 3 switches (which use dedicated ASICs to perform high-speed inter-VLAN routing across broadcast domains), and FlexConnect AP mode (which enables local traffic switching at branch offices during WLC controller outages).

Step-by-Step Solution

1
Identify the virtualization requirement.
Direct execution on bare-metal hardware without a host OS requires a Type 1 (bare-metal) hypervisor, such as VMware ESXi or Cisco UCS B-Series hypervisors.
Type 2 hypervisors require an underlying host OS (e.g., Windows/Linux), adding overhead.
2
Identify the routing component requirement.
Wire-speed inter-VLAN packet forwarding using hardware ASICs requires a Layer 3 switch (multilayer switch).
Layer 2 switches do not perform IP routing between subnets, while software-based routers lack hardware ASIC switching tables for high-density campus LANs.
3
Identify the wireless AP mode requirement.
FlexConnect mode (formerly REAP) allows lightweight APs to switch client data traffic locally when the CAPWAP control tunnel to the WLC is disrupted.
Local mode APs drop client traffic or cease forwarding when CAPWAP connection to the WLC drops.

Key Concept

Network Component Roles and Virtualization Architecture
Estimated Time:1m 30s
Question 859Question →

A network engineer connects two Cisco Catalyst switches using interface GigabitEthernet0/1. Switch-1 is configured with the commands 'switchport mode dynamic desirable' and 'switchport trunk native vlan 10'. Switch-2 is configured with 'switchport mode dynamic auto' and 'switchport trunk native vlan 20'. Assuming default Dynamic Trunking Protocol (DTP) settings, which statement accurately describes the resulting operational state of this interswitch connection?

Show answer & explanation

Answer: An 802.1Q trunk will form successfully, but a native VLAN mismatch will occur, causing untagged traffic from VLAN 10 on Switch-1 to cross into VLAN 20 on Switch-2.

Answer

An 802.1Q trunk will form successfully, but a native VLAN mismatch will occur, causing untagged traffic from VLAN 10 on Switch-1 to cross into VLAN 20 on Switch-2.
When one switch interface is configured as 'dynamic desirable' and the opposite interface is 'dynamic auto', Dynamic Trunking Protocol (DTP) successfully negotiates the link into an operational 802.1Q trunk. However, because Switch-1 uses VLAN 10 as its native VLAN and Switch-2 uses VLAN 20, 802.1Q untagged frame behavior causes traffic sent on VLAN 10 from Switch-1 to arrive untagged and be placed into VLAN 20 on Switch-2. This native VLAN mismatch generates continuous syslog alerts via CDP.

Step-by-Step Solution

1
Evaluate DTP Negotiation Modes
Dynamic Desirable on Switch-1 actively sends DTP frames, while Dynamic Auto on Switch-2 listens and responds positively to DTP trunk requests.
DTP mode dynamic desirable paired with dynamic auto results in an operational trunk link.
2
Analyze Native VLAN Configuration
Switch-1 expects untagged frames to belong to VLAN 10, whereas Switch-2 expects untagged frames to belong to VLAN 20.
802.1Q trunks do not tag frames belonging to the native VLAN across the link header.
3
Determine Frame Delivery Behavior and Protocol Alerts
Untagged frames sent from VLAN 10 on Switch-1 travel across the trunk untagged and are ingested into VLAN 20 by Switch-2. Cisco Discovery Protocol (CDP) detects this discrepancy and generates syslog messages.
A native VLAN mismatch leads to VLAN hopping/leaking and triggers CDP native VLAN mismatch error logs.

Key Concept

DTP Negotiation Outcomes and 802.1Q Native VLAN Alignment
Question 860Question →

An enterprise network architect is auditing a virtualized campus network deployment. A database workload runs inside a virtual machine (VM) hosted on a bare-metal (Type 1) hypervisor. The hypervisor's virtual switch (vSwitch) is connected via an 802.1Q trunk link to a physical Layer 2 access switch, which in turn connects to a Layer 3 switch serving as the default gateway. If the VM sends a Layer 2 ARP broadcast frame to locate its default gateway, which statement correctly describes how network components handle this broadcast frame?

Show answer & explanation

Answer: The Type 1 hypervisor's vSwitch forwards the broadcast frame across the trunk to the Layer 2 switch, which floods it out all active ports in the same VLAN, while the Layer 3 switch interface processes the frame but does not forward the broadcast beyond the subnet.

Answer

The Type 1 hypervisor's vSwitch forwards the broadcast frame across the trunk to the Layer 2 switch, which floods it out all active ports in the same VLAN, while the Layer 3 switch interface processes the frame but does not forward the broadcast beyond the subnet.
A Layer 2 broadcast frame (such as an ARP request) is flooded by both virtual switches (vSwitches inside a Type 1 hypervisor) and physical Layer 2 switches to all active ports within the assigned VLAN. The Layer 3 device processes the ARP request to reply with its MAC address, but boundaried Layer 3 interfaces strictly restrict broadcast frames from being forwarded outside their local subnet.

Step-by-Step Solution

1
Analyze the role of the Type 1 hypervisor vSwitch
The Type 1 bare-metal hypervisor directly controls hardware resources. Its internal virtual switch operates as a standard Layer 2 switch, forwarding the VM's Layer 2 broadcast frame out the physical uplink trunk connected to the access switch.
Type 1 hypervisors do not require a host OS, and vSwitches maintain Layer 2 VLAN segregation and broadcast functionality.
2
Evaluate the forwarding behavior of the physical Layer 2 switch
The physical Layer 2 access switch receives the broadcast frame on the 802.1Q trunk and floods it to all other operational access and trunk ports belonging to that specific VLAN.
Switches separate collision domains per port but preserve broadcast domains per VLAN.
3
Determine the boundary behavior at the Layer 3 gateway switch
The Layer 3 switch receives the ARP request on its Switched Virtual Interface (SVI) or routed port for that VLAN, processes the ARP broadcast locally to send an ARP response, but does not forward the broadcast frame to any other IP interfaces/subnets.
Layer 3 boundaries (routed interfaces and SVIs) define the edge of a Layer 2 broadcast domain.

Key Concept

Collision vs Broadcast Domains across Physical and Virtual Components
Estimated Time:2m 0s
PreviousPage 43 / 100Next
All practice questions — Cisco CCNA | Examkin