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Question 1101Question →

A network technician is provisioning interface FastEthernet 0/1 for a newly attached workstation. Which two Cisco IOS commands must be executed in interface configuration mode to manually set the port as a static access interface assigned to VLAN 20? (Select two.)

Select all that apply

Show answer & explanation

Answer: switchport mode access; switchport access vlan 20

Answer

The two required interface configuration commands are 'switchport mode access' and 'switchport access vlan 20'.
To complete access port configuration, the command 'switchport mode access' sets the administrative mode to access, while 'switchport access vlan 20' binds the port to the specific VLAN ID.

Step-by-Step Solution

1
Set the port mode
Interface is forced into access mode using 'switchport mode access'
Ensures DTP negotiation does not convert the port into a trunk link
2
Assign the VLAN membership
Interface is assigned to VLAN 20 using 'switchport access vlan 20'
Maps untagged frames received on this interface to broadcast domain 20

Key Concept

Access Port VLAN Configuration Syntax
Question 1102Question →

A switch port running classic IEEE 802.1D Spanning Tree Protocol (STP) detects link UP on a non-PortFast access interface. Place the 802.1D STP port states in the exact chronological sequence through which the interface transitions from link initialization to fully active frame processing.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct operational sequence of classic 802.1D STP port states from link bring-up to active data transmission is: Blocking State -> Listening State -> Learning State -> Forwarding State.
Under standard IEEE 802.1D Spanning Tree Protocol, non-PortFast interfaces progress strictly through Blocking, Listening, Learning, and Forwarding states. The Blocking state prevents loops upon initialization; Listening (15s Forward Delay) processes BPDUs and determines port roles; Learning (15s Forward Delay) builds MAC address tables from source MACs; and Forwarding permits normal data payload processing.

Step-by-Step Solution

1
Identify the initial non-functional state upon physical link activation.
The port initializes in the Blocking State.
STP ports default to Blocking to discard user data frames and prevent switching loops while listening for control frames (BPDUs).
2
Identify the state where STP role determination occurs.
The port moves into the Listening State.
During the Listening phase (lasting 15 seconds by default), the switch processes and sends BPDUs to determine Root Bridge and port roles without populating MAC tables or forwarding data frames.
3
Identify the state where address table construction begins.
The port transitions to the Learning State.
After the first 15-second Forward Delay timer expires, the port enters Learning where it examines source MAC addresses of incoming frames to build the MAC address table, but still drops payload data frames.
4
Identify the final fully functional state.
The port enters the Forwarding State.
After the second 15-second Forward Delay timer expires (total 30 seconds convergence), the port transitions to Forwarding where it actively forwards and receives user data frames.

Key Concept

IEEE 802.1D STP Sequential Port State Transitions
Estimated Time:1m 15s
Question 1103Question →

An organization is deploying an in-house real-time voice communications protocol across their WAN links. The network team recommends using User Datagram Protocol (UDP) instead of Transmission Control Protocol (TCP) for the media transport path. Which fundamental Layer 4 header property supports this recommendation by minimizing protocol overhead for delay-sensitive traffic?

Show answer & explanation

Answer: UDP utilizes a fixed header size of 8 bytes, whereas TCP requires a minimum header size of 20 bytes.

Answer

UDP utilizes a fixed header size of 8 bytes, whereas TCP requires a minimum header size of 20 bytes.
The correct answer highlights that UDP maintains a fixed header size of only 8 bytes (comprising Source Port, Destination Port, Length, and Checksum). In contrast, a TCP header has a minimum size of 20 bytes and can expand up to 60 bytes with options. For small real-time voice payloads sent at high packet rates, reducing Layer 4 header overhead from 20 bytes to 8 bytes significantly decreases network bandwidth consumption and latency.

Step-by-Step Solution

1
Analyze transport layer requirements for real-time voice traffic.
Real-time voice requires minimal delay and low protocol overhead; missing payload data is preferred over delayed retransmissions.
Late audio packets are discarded by voice codecs anyway, making TCP reliability mechanics counterproductive.
2
Compare Layer 4 header overhead between UDP and TCP.
UDP features a lean 8-byte fixed header (Source Port, Destination Port, Length, Checksum), while TCP has a 20-byte base header (plus options up to 60 bytes).
The smaller header footprint reduces bandwidth consumption and processing overhead per packet.

Key Concept

TCP vs UDP Header Overhead and Protocol Mechanics
Question 1104Question →

A network administrator is deploying a dynamic Layer 2 EtherChannel using the Link Aggregation Control Protocol (LACP) between Switch-A and Switch-B across two physical interfaces. Switch-A must actively initiate channel negotiation, whereas Switch-B must only listen and respond to incoming LACP negotiation requests.

Which two configuration statements correctly describe the settings required to establish this EtherChannel bundle? (Select two.)

Select all that apply

Show answer & explanation

Answer: Switch-A member interfaces must be configured with channel-group 1 mode active.; Switch-B member interfaces must be configured with channel-group 1 mode passive.

Answer

To form an LACP EtherChannel where one switch actively initiates negotiation and the other responds, Switch-A member interfaces must be configured with 'channel-group 1 mode active' and Switch-B member interfaces must be configured with 'channel-group 1 mode passive'.
In LACP dynamic EtherChannel configuration, 'active' mode initiates LACP negotiations by sending LACP frames, while 'passive' mode responds to incoming LACP negotiation frames without sending them unprompted. An active-to-passive pairing successfully establishes the EtherChannel bundle.

Step-by-Step Solution

1
Analyze protocol negotiation requirements for LACP.
LACP supports two modes: active (initiates negotiation) and passive (responds to negotiation).
Switch-A must initiate negotiation, so it requires active mode. Switch-B must only respond, so it requires passive mode.
2
Evaluate protocol compatibility.
PAgP modes (desirable, auto) cannot pair with LACP modes (active, passive).
Configuring desirable mode on Switch-B attempts PAgP negotiation, causing negotiation failure with an LACP active switch.
3
Verify physical interface parameter consistency requirements.
All interfaces bundled into an EtherChannel on a local switch must share identical settings.
Mismatched native VLANs or trunk settings across member links on the same switch prevent the EtherChannel from bundling successfully.

Key Concept

LACP EtherChannel Mode Compatibility and Member Port Prerequisites
Question 1105Question →

A network engineer is provisioning subnets from the allocated summary block 172.25.192.0/20172.25.192.0/20 to expand an enterprise corporate network. The design specification requires Subnet A to accommodate at least 1,000 usable host endpoints and to be allocated starting from the very first available boundary of the 172.25.192.0/20172.25.192.0/20 block. Additionally, all assigned addresses must strictly comply with RFC 1918 private IPv4 space. What is the last usable IPv4 host address on Subnet A?

Show answer & explanation

Answer: 172.25.195.254

Answer

172.25.195.254
To support at least 1,000 usable hosts, a subnet requires 10 host bits because 210−2=1,0222^{10} - 2 = 1,022 usable addresses (29−2=5102^9 - 2 = 510 is insufficient). Subtracting 10 host bits from 32 total bits yields a /22/22 subnet mask (255.255.252.0255.255.252.0). Allocating a /22/22 subnet from the start of the block 172.25.192.0/20172.25.192.0/20 results in a subnet spanning 172.25.192.0172.25.192.0 to 172.25.195.255172.25.195.255. The last usable IPv4 address is one less than the broadcast address, which is 172.25.195.254172.25.195.254. Furthermore, 172.25.192.0/20172.25.192.0/20 is fully within the RFC 1918 private IP range (172.16.0.0/12172.16.0.0/12).

Step-by-Step Solution

1
Determine required host bits (hh) and prefix length
2h−2≥1,000  ⟹  210−2=1,022≥1,0002^h - 2 \ge 1,000 \implies 2^{10} - 2 = 1,022 \ge 1,000, so h=10h = 10 host bits. The prefix length is 32−10=/2232 - 10 = /22.
Subnet sizing requires finding the smallest power of 2 minus 2 for network and broadcast overhead that satisfies the host capacity requirement.
2
Verify RFC 1918 private addressing compliance
The block 172.25.192.0/20172.25.192.0/20 resides within the Class B private address space of 172.16.0.0/12172.16.0.0/12 (172.16.0.0172.16.0.0 to 172.31.255.255172.31.255.255).
RFC 1918 mandates that enterprise private networks use designated non-routable public IP blocks.
3
Calculate the subnet boundary and broadcast address
A /22/22 prefix has a block size of 44 in the third octet (210−8=42^{10-8} = 4). Starting at 172.25.192.0172.25.192.0, the network spans 172.25.192.0172.25.192.0 to 172.25.195.255172.25.195.255. The broadcast address is 172.25.195.255172.25.195.255.
Adding the block size minus 1 to the starting third octet gives the highest octet boundary for the subnet.
4
Identify the last usable host address
The last usable IP address is one position below the broadcast address: 172.25.195.254172.25.195.254.
The usable host range is bounded between the network ID (+1+1) and the broadcast ID (−1-1).

Key Concept

VLSM host calculation and RFC 1918 private IPv4 address boundaries
Question 1106Question →

An administrator notices CDP log messages indicating a native VLAN mismatch on an 802.1Q trunk link between two switches. Switch-1 is configured with native VLAN 99 on interface GigabitEthernet0/1, while Switch-2 uses the default native VLAN 1 on interface GigabitEthernet0/1. If a host in VLAN 99 on Switch-1 transmits untagged frames across the trunk link, how will Switch-2 process this traffic?

Show answer & explanation

Answer: Switch-2 receives the untagged frames and forwards them into VLAN 1, leading to cross-VLAN traffic leakage.

Answer

Switch-2 receives the untagged frames and forwards them into VLAN 1, leading to cross-VLAN traffic leakage.
Under IEEE 802.1Q trunking rules, frames belonging to the native VLAN are sent untagged across the link. When a receiving switch receives untagged frames, it automatically maps them to its own configured native VLAN. Consequently, traffic originating from VLAN 99 on Switch-1 will be placed into VLAN 1 on Switch-2, resulting in unintended cross-VLAN traffic leakage.

Step-by-Step Solution

1
Analyze how 802.1Q handles native VLAN traffic.
Frames assigned to the native VLAN of a trunk interface are transmitted across the physical link without an added 802.1Q 4-byte header tag.
802.1Q trunking specifies that native VLAN traffic remains untagged for backward compatibility with legacy non-trunking devices.
2
Evaluate the behavior of the receiving switch when native VLAN settings are mismatched.
Switch-2 receives untagged frames from Switch-1 (sent from VLAN 99) and places them into Switch-2's configured native VLAN (VLAN 1).
A receiving switch maps any incoming untagged frame directly to its own configured native VLAN.
3
Determine the operational security and switching impact.
Traffic leaks across VLAN boundaries between VLAN 99 on Switch-1 and VLAN 1 on Switch-2, creating a security risk and potential connectivity issues.
Mismatching native VLANs breaks VLAN isolation for untagged traffic without bringing the physical link down.

Key Concept

802.1Q Native VLAN Tagging Mechanics and Traffic Leakage
Question 1107Question →

A network administrator is inspecting a port configuration on a Cisco Catalyst switch after connecting an end-host workstation. The output of the command `show interfaces fastethernet 0/15 switchport` displays the following information:

text
Name: Fa0/15
Administrative Mode: dynamic auto
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: native
Negotiation of Trunking: On
Access Mode VLAN: 20 (VLAN0020)
Trunking Native Mode VLAN: 1 (default)

Which statement correctly explains why the operational mode of interface FastEthernet 0/15 is reported as `static access`?

Show answer & explanation

Answer: The connected end-host does not send Dynamic Trunking Protocol (DTP) negotiation frames, so the port defaults to operating as an access port in VLAN 20.

Answer

The connected end-host does not send Dynamic Trunking Protocol (DTP) negotiation frames, so the port defaults to operating as an access port in VLAN 20.
The Administrative Mode of FastEthernet 0/15 is `dynamic auto`, meaning the interface is capable of becoming a trunk if the neighboring device actively requests it (such as a port in `dynamic desirable` or `trunk` mode). Because an end-host workstation does not run Dynamic Trunking Protocol (DTP), no DTP frames are received. Consequently, the interface defaults to functioning as a single-VLAN access port assigned to Access Mode VLAN 20.

Step-by-Step Solution

1
Analyze the Administrative Mode and Operational Mode from the CLI output.
Administrative Mode is `dynamic auto` and Operational Mode is `static access`.
Administrative Mode indicates how the port is configured to negotiate, while Operational Mode shows its actual behavior.
2
Evaluate DTP behavior in `dynamic auto` mode.
Ports set to `dynamic auto` respond to DTP negotiation (desirable or trunk) but will not initiate DTP packets to form a trunk.
Since the end device is a host workstation, no DTP packets are received by the switch port.
3
Determine the operational state and active VLAN.
Failing to form a trunk link causes the switch port to fall back to access mode, assigning untagged host traffic to Access Mode VLAN 20.
An un-negotiated dynamic switchport defaults to an access port carrying traffic for its configured access VLAN.

Key Concept

DTP Negotiation Mechanics and Access Port Operational States
Question 1108Question →

An enterprise network topology running Rapid PVST+ consists of three switches: Switch-1, Switch-2, and Switch-3.

- Switch-1 is configured as the Root Bridge for VLAN 20 with a priority of 4096.
- Switch-2 connects to Switch-1 via a 10 Gigabit Ethernet link (10 Gbps10\text{ Gbps}, STP cost = 2).
- Switch-3 connects directly to Switch-1 via a 1 Gigabit Ethernet link (Gi0/1, STP cost = 4).
- Switch-3 also connects to Switch-2 via two parallel 1 Gigabit Ethernet links: Gi0/2 (connected to Switch-2 Gi0/1) and Gi0/3 (connected to Switch-2 Gi0/2).
- All interface STP costs and port priorities use default Cisco values.

Which port role and operational state will interface Gi0/2 on Switch-3 assume for VLAN 20?

Show answer & explanation

Answer: Alternate port role in the Discarding state

Answer

Interface Gi0/2 on Switch-3 assumes the Alternate port role in the Discarding state.
Switch-3 evaluates all available paths to Root Bridge Switch-1. The direct 1 Gbps link on interface Gi0/1 provides a path cost of 4, whereas traversing Switch-2 via interface Gi0/2 yields a path cost of 6 (cost 2 from Switch-2 to Switch-1 plus cost 4 from Switch-3 to Switch-2). Consequently, Gi0/1 is elected as Switch-3's Root Port. On the segments connecting Switch-2 and Switch-3, Switch-2 advertises a lower root path cost (2) than Switch-3 (4), electing Switch-2 as the designated bridge. Interface Gi0/2 on Switch-3 receives BPDUs from Switch-2 and is designated as an Alternate port in the Discarding state.

Step-by-Step Solution

1
Determine the Root Bridge for VLAN 20
Switch-1 is the Root Bridge due to its configured priority of 4096.
The switch with the lowest Bridge ID (Priority + System ID Extension + MAC) becomes the Root Bridge.
2
Calculate cumulative path costs from Switch-3 to the Root Bridge
Direct path via Gi0/1 = 4. Path via Switch-2 (Gi0/2 or Gi0/3) = 2 (Switch-2 to Switch-1) + 4 (Switch-3 to Switch-2) = 6.
Standard Rapid PVST+ path cost for 10 Gbps10\text{ Gbps} is 2 and for 1 Gbps1\text{ Gbps} is 4.
3
Select Switch-3's Root Port
Gi0/1 is selected as the Root Port on Switch-3 and transitions to the Forwarding state.
The interface with the lowest cumulative path cost to the Root Bridge is elected as the Root Port.
4
Determine port roles for Switch-3's remaining interfaces (Gi0/2 and Gi0/3)
Switch-2's root path cost (2) is less than Switch-3's root path cost (4), making Switch-2 the Designated Bridge on the inter-switch links between Switch-2 and Switch-3. Gi0/2 on Switch-3 receives superior BPDUs from Switch-2 and is placed into the Alternate role in the Discarding state.
Non-root ports receiving superior BPDUs from another switch become Alternate ports in Discarding state under Rapid PVST+.

Key Concept

Rapid PVST+ Root Port and Alternate Port election rules based on cumulative root path costs and designated bridge tie-breakers.
Question 1109Question →

A network administrator inspects a Cisco router interface configured with dynamic IPv6 address generation and observes the assigned global unicast address `2001:db8:a1b2:c3d4:0211:22ff:fe33:4455/64`. Based on IEEE EUI-64 specification rules, which MAC address was assigned to the physical interface?

Show answer & explanation

Answer: 0011.2233.4455

Answer

The MAC address assigned to the physical interface is 0011.2233.4455.
To derive the original MAC address from a Modified EUI-64 IPv6 interface ID (`0211:22ff:fe33:4455`), remove the inserted `FFFE` hex value from the center to yield six bytes (`02:11:22:33:44:55`) and invert the 7th bit of the first byte (`02` hex = `0000 0010` binary -> inverted to `0000 0000` binary = `00` hex). This reveals the original MAC address `0011.2233.4455`.

Step-by-Step Solution

1
Identify the 64-bit Interface Identifier (Interface ID) from the IPv6 address.
The Interface ID is `0211:22ff:fe33:4455`.
In a /64 prefix, the last 64 bits represent the host portion (Interface ID).
2
Remove the 16-bit `ff:fe` sequence inserted into the middle of the MAC address during EUI-64 generation.
Removing `ff:fe` from `0211:22ff:fe33:4455` leaves 6 bytes: `02-11-22-33-44-55`.
EUI-64 creation inserts `FFFE` between the OUI (first 24 bits) and NIC specific bits (last 24 bits).
3
Invert the 7th bit (Universal/Local bit) of the first byte.
The first byte `02` in binary is `0000 0010`. Inverting the 7th bit yields `0000 0000`, which is `00` in hex. Combining all bytes yields `0011.2233.4455`.
The 7th bit is flipped from 0 to 1 when constructing Modified EUI-64, so it must be flipped back from 1 to 0 to restore the original MAC address.

Key Concept

Modified EUI-64 MAC-to-IPv6 Address Derivation
Question 1110Question →

A network administrator is configuring virtual networking on a bare-metal hypervisor host equipped with redundant physical network interface cards (pNICs). The host accommodates multiple virtual machines (VMs) belonging to different department networks. Which two statements accurately describe the forwarding and operational characteristics of a virtual switch (vSwitch) in this environment? (Select two.)

Select all that apply

Show answer & explanation

Answer: Intra-host traffic between virtual machines on the same VLAN is switched internally by the vSwitch without egressing to the physical network interface.; Port groups on the vSwitch allow administrators to apply network policies and VLAN tags to isolate traffic from distinct groups of virtual interfaces.

Answer

The correct statements are that intra-host traffic between virtual machines on the same VLAN is switched internally by the vSwitch without egressing to the physical network interface, and port groups on the vSwitch allow administrators to apply network policies and VLAN tags to isolate traffic from distinct groups of virtual interfaces.
Virtual switches (vSwitches) operate inside the hypervisor to provide Layer 2 connectivity for virtual machines. When two VMs on the same physical host communicate within the same VLAN, the vSwitch forwards traffic locally in system memory, avoiding unnecessary transmission over physical NICs. Additionally, port groups on a vSwitch act as logical switchport configurations, allowing network administrators to define VLAN tags, traffic shaping, and security policies for connected vNICs.

Step-by-Step Solution

1
Analyze how virtual switches handle local VM-to-VM communication on the same physical host.
Recognize that when two VMs are on the same host and VLAN, the vSwitch forwards frames directly between virtual ports inside memory without sending frames out through the physical network interface cards (pNICs).
This reduces physical link utilization and optimizes intra-host throughput.
2
Evaluate how logical segment isolation and policy enforcement are managed on a virtual switch.
Identify that vSwitches use port groups to group virtual machine network interfaces (vNICs) and assign configuration settings such as 802.1Q VLAN IDs and security settings.
Port groups act as logical access ports or trunks to enforce traffic isolation per tenant or department.
3
Evaluate incorrect assertions regarding Type 1 hypervisor architecture and Spanning Tree Protocol.
Dismiss the ideas that a Type 1 hypervisor relies on a standard host operating system network stack or that vSwitches participate in Spanning Tree Protocol (STP) BPDU exchanges.
Type 1 hypervisors run directly on hardware, and standard vSwitches do not run STP or form loops because they do not forward frames between physical uplinks.

Key Concept

Virtual Switch Architecture and Traffic Forwarding
Estimated Time:1m 30s
Question 1111Question →

Match each Cisco Wireless LAN Controller (WLC) physical or logical interface to its primary operational role and management connectivity requirement.

Click a left item, then click its matching right item

Items

Service Port Interface
Management Interface
Virtual Interface
Dynamic Interface

Matches

Show answer & explanation

Answer

Service Port Interface pairs with out-of-band management over a separate routing table. Management Interface pairs with in-band WLC administration, CAPWAP tunnel termination, and RADIUS. Virtual Interface pairs with web authentication redirection, DHCP relay proxying, and mobility. Dynamic Interface pairs with mapping WLAN SSIDs to 802.1Q VLAN trunks.
Each Cisco WLC interface has a distinct role: Service Port provides out-of-band access via an isolated routing table; Management Interface manages in-band CAPWAP tunnels, GUI/SSH access, and AAA; Virtual Interface handles web authentication redirects using a non-routable IP address; and Dynamic Interfaces map SSIDs to enterprise switchport VLANs.

Step-by-Step Solution

1
Identify out-of-band management capabilities
Match Service Port Interface to out-of-band access
The Service Port is physically separated from data ports and resides in an isolated management network routing table.
2
Identify in-band controller administration and AP CAPWAP termination interface
Match Management Interface to in-band administrative operations and CAPWAP tunnel endpoint functions
Lightweight APs discover and establish CAPWAP management tunnels to the controller's Management Interface IP address.
3
Determine the interface responsible for web redirection and mobility signaling
Match Virtual Interface to web auth redirection and relay proxying
The Virtual Interface uses an internal non-routable IP address to handle Layer 3 guest web portal redirects.
4
Identify data plane mapping for wireless client payload traffic
Match Dynamic Interface to SSID-to-VLAN trunk mapping
Dynamic interfaces bind configured WLANs to specific 802.1Q VLAN tags on distribution switchports.

Key Concept

Cisco WLC Logical and Physical Interface Roles for In-Band and Out-Of-Band Management
Question 1112Question →

A network administrator provisions a small subnetwork for a server cluster using a subnet mask with a prefix length of /29/29. How many usable host IPv4 addresses are available on this subnet?

Show answer & explanation

Answer: 6

Answer

The subnet provides 6 usable host IPv4 addresses.
With a prefix length of /29/29, there are 32−29=332 - 29 = 3 host bits available. The formula to calculate usable host addresses is 2n−22^n - 2, where nn is the host bit count. Calculating 23−2=8−2=62^3 - 2 = 8 - 2 = 6 yields 6 usable host addresses.

Step-by-Step Solution

1
Determine host bits from CIDR prefix
3 host bits
An IPv4 address consists of 32 bits, so 32−29=332 - 29 = 3 bits remain for host identification.
2
Calculate total IP address space
8 total addresses
Total address space equals 2n2^n where nn is the host bit count (23=82^3 = 8).
3
Subtract reserved addresses
6 usable host addresses
The network address (all host bits 0) and broadcast address (all host bits 1) cannot be assigned to end devices.

Key Concept

IPv4 Usable Host Calculation
Estimated Time:45s
Question 1113Question →

A network administrator needs to manually configure the base bridge priority for VLAN 30 on a Cisco Catalyst switch running Rapid PVST+. Which configured base priority value is valid and will be accepted by Cisco IOS?

Show answer & explanation

Answer: 4096

Answer

4096 is a valid base priority because Rapid PVST+ requires bridge priority values to be configured in increments of 4096.
In Rapid PVST+, the 16-bit Priority field is divided into a 4-bit base priority field and a 12-bit System ID Extension field (which carries the VLAN ID). Because only 4 bits are used for the base priority, configurable values must be increments of 40964096 (such as 0,4096,8192,122880, 4096, 8192, 12288, etc.). Selecting 4096 provides a valid base priority value.

Step-by-Step Solution

1
Identify the STP bridge priority configuration requirement for Rapid PVST+.
Bridge priority values must be configured in multiples of 4096 due to the 12-bit System ID Extension field in the 802.1t bridge ID structure.
Cisco IOS reserves 12 bits for the VLAN ID (System ID Extension) within the 16-bit Priority field, leaving 4 bits for the base priority.
2
Evaluate the given options to find a valid multiple of 4096.
4096 is equal to 4096×14096 \times 1, making it a valid configurable base priority value.
Values such as 3000, 4000, and 4126 are not valid base priority multiples.

Key Concept

Rapid PVST+ Bridge Priority and System ID Extension
Question 1114Question →

A network administrator is evaluating Layer 4 protocol mechanisms for application deployment across an enterprise network. Which of the following features are characteristics unique to TCP when compared to UDP? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Explicit connection setup using a three-way handshake sequence before transmitting data; Flow control managed dynamically through receiver window size adjustments

Answer

TCP uniquely provides stateful session establishment via a three-way handshake and flow control through dynamic sliding window adjustments, whereas UDP is stateless, connectionless, and lacks windowing flow control.
TCP is a connection-oriented protocol that establishes a stateful connection via a three-way handshake prior to data exchange and employs dynamic window size adjustments for flow control to match receiver processing capacity.

Step-by-Step Solution

1
Analyze transport protocol connection management mechanisms.
TCP requires a three-way handshake (SYN, SYN-ACK, ACK) to establish a connection state between endpoints before payload exchange, whereas UDP is connectionless and sends datagrams without prior signaling.
Establishing connection state is essential for TCP reliability.
2
Analyze transport protocol traffic regulation capabilities.
TCP implements flow control using dynamic window size fields in its header to prevent sender buffer overrun at the receiver. UDP contains no window field or flow control mechanism.
Windowing allows TCP to adapt transmission rates to receiver processing limits.
3
Evaluate distractor properties against protocol specifications.
An 8-byte header and stateless delivery belong to UDP (TCP headers are at least 20 bytes). Multicast/broadcast support is exclusive to connectionless transport (UDP), as TCP is limited to unicast traffic.
Distractors represent characteristics inherent to UDP rather than TCP.

Key Concept

TCP vs UDP Operational Differences and Mechanisms
Question 1115Question →

Four Cisco switches (SW1, SW2, SW3, and SW4) are interconnected in a enterprise mesh topology running Rapid PVST+ for VLAN 10. The bridge priorities (base priority values) and MAC addresses for VLAN 10 are configured as follows:

SwitchBase Bridge PriorityMAC Address
SW140960001.AAAA.AAAA
SW2286720002.BBBB.BBBB
SW3327680003.CCCC.CCCC
SW4327680004.DDDD.DDDD

The inter-switch physical links and operational speeds are configured as follows:
- SW1 Gi0/1 <--> SW2 Gi0/1 (1 Gbps)
- SW1 Gi0/2 <--> SW3 Gi0/1 (1 Gbps)
- SW2 Gi0/2 <--> SW4 Gi0/1 (1 Gbps)
- SW2 Gi0/3 <--> SW3 Gi0/2 (100 Mbps)
- SW3 Gi0/3 <--> SW4 Gi0/2 (1 Gbps)

All switch ports use default Rapid PVST+ 802.1w short path costs. Which spanning-tree port role and operational state will interface Gi0/2 on SW4 assume for VLAN 10?

Show answer & explanation

Answer: Alternate port in the Discarding state

Answer

Alternate port in the Discarding state
SW1 is the Root Bridge because it has the lowest Bridge ID (4106:0001.AAAA.AAAA). Both SW2 and SW3 elect their direct 1 Gbps connections to SW1 as Root Ports, giving both switches a Root Path Cost of 4. SW4 has two 1 Gbps paths to the root: via SW2 (cost 4 + 4 = 8) and via SW3 (cost 4 + 4 = 8). Because the path costs are tied at 8, SW4 breaks the tie using the lowest upstream Designated Bridge ID. SW2's Bridge ID (28682:0002.BBBB.BBBB) is lower than SW3's Bridge ID (32778:0003.CCCC.CCCC), so SW4 selects Gi0/1 as its Root Port. On the link between SW3 Gi0/3 and SW4 Gi0/2, SW3 advertises a lower Root Path Cost (4) than SW4 (8). Thus, SW3 Gi0/3 becomes the Designated Port for the segment, and SW4 Gi0/2 transitions to an Alternate port role in the Discarding state.

Step-by-Step Solution

1
Determine the Root Bridge for VLAN 10.
SW1 total priority = 4096+10=41064096 + 10 = 4106. Since 41064106 is the lowest bridge priority in the network, SW1 becomes the Root Bridge.
Rapid PVST+ adds the VLAN ID (1010) to the base priority to form the total Bridge Priority.
2
Calculate Root Path Costs for SW2 and SW3.
SW2 Root Port = Gi0/1 (Cost 44). SW3 Root Port = Gi0/1 (Cost 44).
1 Gbps link cost under default short path cost mode is 44.
3
Evaluate SW4 Root Port election between Gi0/1 and Gi0/2.
Path via Gi0/1 (SW2): Cumulative cost =4+4=8= 4 + 4 = 8. Designated Bridge ID =28682:0002.BBBB.BBBB= 28682:0002.BBBB.BBBB.
Path via Gi0/2 (SW3): Cumulative cost =4+4=8= 4 + 4 = 8. Designated Bridge ID =32778:0003.CCCC.CCCC= 32778:0003.CCCC.CCCC.
SW4 chooses Gi0/1 as its Root Port (Forwarding state) because SW2 has a lower Bridge ID than SW3.
When cumulative path costs are tied, the upstream Designated Bridge ID breaks the tie.
4
Determine Designated Port and Alternate Port roles on the link between SW3 Gi0/3 and SW4 Gi0/2.
SW3 advertises Root Path Cost 44 on Gi0/3. SW4 advertises Root Path Cost 88 on Gi0/2. SW3 wins Designated Port role (Forwarding state). SW4 Gi0/2 becomes an Alternate Port in the Discarding state.
The bridge advertising the lower cumulative Root Path Cost on a segment becomes the Designated Bridge for that link.

Key Concept

Rapid PVST+ Port Role Election and State Transitions
Question 1116Question →

A network administrator needs to explicitly configure interface GigabitEthernet1/0/12 to function strictly as a non-trunking Layer 2 access port on a Cisco Catalyst switch. Which Cisco IOS command must be entered in interface configuration mode to achieve this?

Show answer & explanation

Answer: switchport mode access

Answer

The command 'switchport mode access' explicitly configures an interface to operate as a static Layer 2 access port.
The command 'switchport mode access' configures the switch interface to operate purely as an access port, ensuring it handles untagged traffic for a single VLAN and does not form a trunk link with attached devices.

Step-by-Step Solution

1
Identify the requirement
The port must be configured strictly as a static access port (non-trunking).
By default, Cisco switch ports may negotiate trunking via Dynamic Trunking Protocol (DTP).
2
Select the correct Cisco IOS CLI command for setting the operational mode
Use 'switchport mode access'.
Executing 'switchport mode access' under interface configuration mode locks the interface into access mode and prevents trunk formation.

Key Concept

Access Port Interface Mode Configuration
Question 1117Question →

An administrator issues the command `show spanning-tree interface gigabitethernet 0/1` on a Cisco Catalyst switch connected to a workstation. The command output indicates that the port is in the `FWD` state and lists `P2p Edge` under the Type column. Which operational behavior is directly associated with this interface status?

Show answer & explanation

Answer: The interface immediately transitions to the forwarding state upon linkup by bypassing the listening and learning states.

Answer

The interface immediately transitions to the forwarding state upon linkup by bypassing the listening and learning states.
When an interface is designated as an Edge port (PortFast enabled), it transitions directly to the forwarding state upon link activation. This bypasses the listening and learning states, preventing convergence delays for end-user workstations.

Step-by-Step Solution

1
Interpret the CLI output port type
The `P2p Edge` designation indicates that Cisco PortFast is enabled on a point-to-point link connected to an end device.
Edge ports in Spanning Tree Protocol represent host-facing connections that do not lead to another switch.
2
Identify the functional mechanism of PortFast
PortFast bypasses the 802.1D Listening (15s) and Learning (15s) states, placing the interface into Forwarding immediately upon link UP.
This allows hosts to quickly obtain IP address assignments via DHCP without timing out during boot.

Key Concept

PortFast / Edge Port State Transition and Convergence Mechanics
Question 1118Question →

A network administrator is configuring a routed (Layer 3) EtherChannel bundle using LACP on a Cisco Catalyst switch. The administrator creates the logical interface using `interface Port-channel 10`, executes `no switchport`, and assigns an IPv4 address. Next, the administrator enters interface configuration mode for GigabitEthernet0/1, GigabitEthernet0/2, and GigabitEthernet0/3. On GigabitEthernet0/1 and GigabitEthernet0/2, the administrator issues `no switchport` followed by `channel-group 10 mode active`. However, on interface GigabitEthernet0/3, the administrator issues `channel-group 10 mode active` without first executing `no switchport`.

What is the resulting operational status of interface GigabitEthernet0/3 in the output of `show etherchannel summary`?

Show answer & explanation

Answer: It remains in an independent (I) state and fails to bundle because its Layer 2 switchport mode does not match the Layer 3 configuration of the Port-Channel.

Answer

The interface remains in an independent (I) state and fails to join the EtherChannel bundle because its Layer 2 switchport setting does not match the Layer 3 configuration of the logical Port-Channel interface.
For a physical interface to join a Layer 3 EtherChannel, both the logical Port-Channel and all member physical interfaces must have 'no switchport' configured. Because GigabitEthernet0/3 retains its default Layer 2 switchport state, it fails the parameter compatibility check and is placed in an independent (I) state in 'show etherchannel summary'.

Step-by-Step Solution

1
Identify the configuration of the logical Port-Channel interface.
Port-channel 10 is configured as a Layer 3 (routed) interface via the 'no switchport' command.
EtherChannel member interfaces must match key operational attributes with the Port-Channel interface, including speed, duplex, trunking/routed mode, and allowed VLANs.
2
Analyze the configuration of physical interface GigabitEthernet0/3.
GigabitEthernet0/3 was added to channel-group 10 without executing 'no switchport'.
By default, switch ports operate as Layer 2 interfaces. Without 'no switchport', GigabitEthernet0/3 remains a Layer 2 port while Port-channel 10 is a Layer 3 port.
3
Determine the outcome in 'show etherchannel summary'.
GigabitEthernet0/3 is marked with the 'I' (Independent) flag and is excluded from the active bundle.
Cisco IOS enforces strict attribute consistency; incompatible physical ports are placed in an independent state and cannot aggregate into the channel.

Key Concept

Layer 3 EtherChannel Member Interface Compatibility Requirements
Question 1119Question →

A network administrator is configuring Rapid PVST+ on Switch-A within an enterprise switched topology. Switch-A links to Switch-B and Switch-C over 802.1Q trunk connections carrying multiple VLANs. The administrator executes the command `spanning-tree vlan 20 priority 24576` on Switch-A.

Which two statements correctly describe the resulting Rapid PVST+ operation and configuration characteristics on Switch-A for VLAN 20? (Select two.)

Select all that apply

Show answer & explanation

Answer: Switch-A calculates its effective Bridge Priority for VLAN 20 as 24596 by adding the 12-bit System ID Extension value of 20 to the configured base priority of 24576.; Rapid PVST+ sends BPDUs for VLAN 20 using the IEEE 802.1w structure tagged with a Cisco PVST+ SNAP header destined to multicast MAC address 01-00-0C-CC-CC-CD.

Answer

The correct statements are that Switch-A calculates its effective Bridge Priority for VLAN 20 as 24596 (24576+2024576 + 20) due to the System ID Extension, and that Rapid PVST+ sends BPDUs for VLAN 20 using 802.1w payloads encapsulated in Cisco PVST+ SNAP frames destined to 01-00-0C-CC-CC-CD.
The correct statements recognize that Rapid PVST+ automatically adds the 12-bit VLAN ID (20) to the base priority setting (24576) to form an effective Bridge Priority of 24596, and that Rapid PVST+ encapsulates 802.1w BPDUs into Cisco-specific SNAP frames destined for multicast MAC 01-00-0C-CC-CC-CD.

Step-by-Step Solution

1
Calculate the effective Bridge Priority for VLAN 20
Effective Priority = Base Priority + System ID Extension = 24576+20=2459624576 + 20 = 24596
Cisco Rapid PVST+ implements 802.1t Extended System ID, which combines a 4-bit priority multiplier (in steps of 4096) with the 12-bit VLAN ID to create a unique per-VLAN Bridge ID.
2
Identify the BPDU encapsulation and framing behavior of Rapid PVST+
Rapid PVST+ sends per-VLAN 802.1w RSTP BPDUs tagged over trunks using destination multicast MAC address 01-00-0C-CC-CC-CD
Rapid PVST+ provides rapid convergence per VLAN by running 802.1w mechanics inside Cisco's proprietary PVST+ SNAP frame format.

Key Concept

Rapid PVST+ Bridge ID construction and per-VLAN BPDU frame encapsulation rules
Question 1120Question →

A network administrator is allocated the IPv4 address block 172.20.64.0/21172.20.64.0/21 for datacenter VLAN expansion. The architectural requirement mandates that the block be divided into the maximum possible number of equal-sized subnets such that each subnet can accommodate at least 5050 usable host addresses. If exactly 5050 hosts are assigned in every created subnet, how many usable host IP addresses across the entire /21/21 block remain unassigned?

Show answer & explanation

Answer: 384

Answer

384 usable host IP addresses remain unassigned across all created subnets.
To satisfy the requirement of at least 5050 usable host addresses per subnet while maximizing the number of subnets, 66 host bits are required (26−2=622^6 - 2 = 62 usable host addresses per subnet), resulting in a /26/26 prefix length. Dividing the /21/21 block into /26/26 subnets produces 226−21=322^{26-21} = 32 subnets. With 5050 host addresses assigned per subnet, each subnet has 62−50=1262 - 50 = 12 unassigned usable host addresses. Across all 3232 subnets, the total number of unassigned usable host IP addresses is 32×12=38432 \times 12 = 384.

Step-by-Step Solution

1
Determine the minimum host bits required to support at least 50 usable host addresses per subnet.
6 host bits (h=6h = 6), which yields 26−2=622^6 - 2 = 62 usable host addresses per subnet and a prefix length of /26/26.
Using 5 host bits (25−2=302^5 - 2 = 30) is insufficient for 50 hosts. 6 host bits meet the minimum requirement while maximizing subnet creation.
2
Calculate the total number of /26/26 subnets created from the /21/21 summary block.
226−21=25=322^{26 - 21} = 2^5 = 32 subnets.
Borrowing 5 subnet bits from a /21/21 block creates 32 subnets of size /26/26.
3
Determine the unassigned usable host addresses per subnet when 50 hosts are assigned.
62−50=1262 - 50 = 12 unassigned usable host addresses per subnet.
Network and broadcast addresses are already excluded when calculating the 62 usable host addresses.
4
Multiply the unassigned usable host addresses per subnet by the total number of created subnets.
32 subnets×12 addresses=38432 \text{ subnets} \times 12 \text{ addresses} = 384 total unassigned usable host IP addresses.
Aggregating the unused host capacity across all equal-sized subnets within the allocated block.

Key Concept

IPv4 Subnet Sizing and Usable Host Capacity Calculation
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