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Question 341Question →

A network analyst is investigating an automated host that fails to exchange data with a remote cloud API. Packet capture analysis confirms that physical media connections are operational, Ethernet frames are delivered without CRC errors, IP packets are routed across subnets without loss, and TCP three-way handshakes complete successfully. However, session logs reveal that communication terminates abruptly when the client and server attempt to negotiate character set encoding, data compression, and payload encryption standards. At which layer of the OSI reference model is this operational failure occurring?

Show answer & explanation

Answer: Presentation Layer (Layer 6)

Answer

The operational failure is occurring at the Presentation Layer (Layer 6).
The correct answer identifies the Presentation Layer (Layer 6). This layer acts as the data translator for the network, handling tasks such as character encoding conversion (e.g., ASCII/EBCDIC), data compression, and encryption/decryption formatting so that differing systems can interpret payload syntax properly.

Step-by-Step Solution

1
Analyze lower-layer diagnostic status from the scenario.
Physical (Layer 1), Data Link (Layer 2), Network (Layer 3), and Transport (Layer 4) operations are confirmed working because TCP handshakes complete cleanly.
Eliminates lower layers (1-4) as potential failure points.
2
Identify the functional domain of the reported error.
The failure specifically involves character set encoding, data compression, and cryptographic syntax negotiation.
Isolates the specific network protocol responsibility being executed.
3
Map the functional domain to the correct OSI layer.
Layer 6 (Presentation Layer) handles translation, syntax presentation, encoding standards, compression, and encryption.
Matches the exact functional duties defined for Layer 6.

Key Concept

OSI Layer 6 (Presentation Layer) functions including data translation, character encoding, syntax presentation, compression, and encryption.
Estimated Time:2m 0s
Question 342Question →

A network security engineer is analyzing a packet capture containing IPv6 traffic in an enterprise network. The engineer notes two key requirements being evaluated:
1. An incoming IPv6 packet has a 20-bit header field set by the sending host so that intermediate routers can identify and maintain QoS forwarding for a specific real-time packet flow without inspecting transport layer headers.
2. A dual-stack host auto-configures its IPv6 interface address using EUI-64 SLAAC based on its physical MAC address of 00-15-5D-01-23-45.

Which option correctly identifies the 20-bit IPv6 header field used for flow identification AND the resulting EUI-64 Interface Identifier generated for this host?

Show answer & explanation

Answer: Flow Label header field; EUI-64 Interface Identifier is 0215:5dff:fe01:2345

Answer

The correct option states that the 20-bit header field is the Flow Label and the generated EUI-64 Interface Identifier is 0215:5dff:fe01:2345.
The 20-bit Flow Label field in the IPv6 base header is specifically designated for source hosts to tag sequences of packets belonging to a specific communication flow, enabling intermediate routers to perform QoS handling without inspecting transport-layer headers. For SLAAC address auto-configuration using Modified EUI-64 format, the 48-bit MAC address (00-15-5D-01-23-45) is split into two 24-bit halves, the 16-bit hex sequence FFFE is inserted in the middle (00-15-5D-FF-FE-01-23-45), and the 7th bit (Universal/Local bit) of the first byte is inverted (00000000 becomes 00000010, converting 00 to 02). Combining these yields the interface identifier 0215:5dff:fe01:2345.

Step-by-Step Solution

1
Identify the 20-bit IPv6 base header field designed for stream identification without transport layer parsing.
The 20-bit field is the Flow Label.
The IPv6 base header contains a 20-bit Flow Label field used to label sequences of packets belonging to a specific communication flow. (Traffic Class is an 8-bit field used for DSCP/CoS marking).
2
Split the 48-bit MAC address (00-15-5D-01-23-45) into two 24-bit halves and insert FFFE in the middle.
Inserting FFFE produces 00-15-5D-FF-FE-01-23-45.
Modified EUI-64 address generation requires expanding a 48-bit IEEE MAC address into a 64-bit interface identifier by inserting the 16-bit hexadecimal string FFFE.
3
Invert the 7th bit (Universal/Local bit) of the first byte.
The first byte 00 (00000000 in binary) becomes 02 (00000010 in binary).
IEEE EUI-64 formatting for IPv6 SLAAC requires inverting the 7th bit (the U/L bit) of the Organizationally Unique Identifier (OUI) to denote universal scope.
4
Format the resulting 64-bit sequence into IPv6 colon-hexadecimal notation.
Combining 02-15-5D-FF-FE-01-23-45 into 16-bit quads yields 0215:5dff:fe01:2345.
IPv6 addresses group 16-bit blocks separated by colons with leading zero suppression applied within each block.

Key Concept

IPv6 Base Header Field Functions (Flow Label vs. Traffic Class) and Modified EUI-64 Interface Identifier Generation Rules
Estimated Time:2m 0s
Question 343Question →

A telemetry system monitoring remote power sub-stations transmits Continuous High-Frequency (CHF) data streams over an unstable satellite connection back to a central control node. To prevent corrupted or incomplete transmissions caused by intermittent connectivity drops, the communication protocol inserts periodic synchronization markers (checkpoints) into the active data stream. When the connection breaks, the protocol uses these markers to resume data exchange from the last acknowledged checkpoint rather than re-initiating the entire transaction or re-authenticating the user channel. Which layer of the OSI reference model is directly responsible for providing this dialogue control and session checkpoint restoration capability?

Show answer & explanation

Answer: Session Layer (Layer 5)

Answer

Session Layer (Layer 5) is responsible for dialogue control and checkpointing.
The correct answer identifies the Session Layer (Layer 5). The primary responsibilities of Layer 5 include establishing, maintaining, and terminating communication sessions between applications, as well as providing dialogue control (managing whose turn it is to transmit) and checkpointing/synchronization markers to enable resumption of data streams following network interruptions.

Step-by-Step Solution

1
Analyze the functional requirements in the scenario.
The scenario highlights dialogue control, insertion of synchronization markers (checkpoints), and session state resumption across connection drops.
Identifying the specific network function isolating the protocol mechanism is required to map it to the correct OSI layer.
2
Map the identified functions to OSI model layer definitions.
Dialogue control (duplex management) and synchronization/checkpointing are explicit, standard responsibilities defined for Layer 5 (Session Layer).
Layer 4 manages TCP/UDP transport segments, Layer 6 manages formatting/encryption, while Layer 5 specifically governs session dialogue boundaries.

Key Concept

OSI Session Layer (Layer 5) Functions & Dialogue Control
Estimated Time:2m 0s
Question 344Question →

During a routine network inspection, a technician inspects a switch's forwarding table to verify local host connectivity within a single broadcast domain. At which layer of the OSI reference model do MAC addresses and frames primarily operate?

Show answer & explanation

Answer: Data Link layer

Answer

Data Link layer
The Data Link layer (Layer 2) of the OSI reference model provides node-to-node data transfer across a shared physical medium. It encapsulates Network layer packets into frames and relies on MAC addresses for local delivery.

Step-by-Step Solution

1
Identify the addressing scheme and Protocol Data Unit (PDU) specified in the scenario.
The scenario highlights MAC addresses and frames inspected on a network switch.
MAC addresses serve as physical interface identifiers, and frames are the corresponding data encapsulation unit.
2
Map MAC addresses and frames to the OSI reference model layer.
MAC addressing and frame creation occur at Layer 2 (Data Link layer).
Layer 2 governs intra-segment communication and hardware-level node identification.

Key Concept

OSI Layer 2 (Data Link Layer) Functions and Addressing
Estimated Time:45s
Question 345Question →

A network technician is configuring traffic management rules for a set of new server applications. Which of the following operational characteristics are uniquely associated with User Datagram Protocol (UDP) as a connectionless transport layer protocol? (SELECT TWO)

Select all that apply

Show answer & explanation

Answer: Low transmission overhead due to the absence of flow control and error recovery mechanisms; Unreliable datagram delivery where dropped packets are not automatically retransmitted by the protocol

Answer

The correct characteristics of UDP as a connectionless protocol are low transmission overhead due to the absence of flow control and error recovery mechanisms, and unreliable datagram delivery where dropped packets are not automatically retransmitted by the protocol.
Connectionless protocols such as UDP operate on a best-effort basis without establishing a formal connection prior to transmission. Consequently, UDP has very low header overhead (8 bytes compared to TCP's 20 bytes) and does not provide transport-layer error recovery, sequence tracking, or retransmission of lost packets.

Step-by-Step Solution

1
Identify the key properties of connectionless transport layer protocols.
Connectionless protocols transmit data datagrams independently without establishing a preliminary session or state.
Understanding the fundamental architecture of UDP at Layer 4 is necessary to distinguish its features from TCP.
2
Evaluate each option against UDP mechanisms.
Options describing low overhead and lack of retransmissions describe UDP. Options describing handshakes, sequence guarantees, or Layer 3 operation are incorrect.
UDP avoids state tracking, acknowledgments, and connection handshakes to minimize latency and overhead.

Key Concept

Connection-Oriented vs Connectionless Transport Protocols (TCP vs UDP)
Question 346Question →

A network engineer is reviewing IPv6 deployment standards and analyzing base header structures for a router interface. Which of the following statements correctly describe the characteristics of IPv6 address representation and header fields? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: The double-colon `::` shorthand notation may only be used a single time within any IPv6 address representation.; The Next Header field in the IPv6 base header identifies either the upper-layer protocol or the type of extension header immediately following.

Answer

The correct statements are that the double-colon `::` notation can only be used once per IPv6 address to prevent ambiguity, and that the Next Header field specifies the upper-layer protocol or extension header that immediately follows.
The option stating that double-colon notation `::` may only be used a single time is correct because using it twice makes the exact 128-bit address ambiguous. The option stating that the Next Header field identifies the upper-layer protocol or extension header is also correct because it provides flexible protocol encapsulation and header chaining.

Step-by-Step Solution

1
Evaluate IPv6 address compression rules.
Confirm that RFC 5952 permits the double-colon notation `::` only once in an address to ensure the 128-bit address can be uniquely expanded.
Multiple double colons make it mathematically impossible for a parser to accurately determine how many 16-bit zero blocks each `::` represents.
2
Examine IPv6 base header field functions.
Identify that the 8-bit Next Header field specifies the protocol encapsulated in the payload or the next extension header in the chain.
IPv6 uses modular extension headers chained together via the Next Header field rather than optional fields inside the base header.
3
Verify incorrect statements against IPv6 specification.
Disprove multiple double colons and correct the definition of Hop Limit (which functions like IPv4 TTL, not QoS prioritization).
QoS functions are handled by Traffic Class and Flow Label, while Hop Limit prevents looping packets.

Key Concept

IPv6 Address Formatting Rules and Extension Header Chaining
Question 347Question →

An entry-level technician is reviewing core IPv6 specifications, address shorthand rules, and packet structures. Which of the following statements correctly describe valid IPv6 characteristics? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Leading zeros within any 16-bit hexadecimal block may be omitted.; The primary IPv6 header has a fixed size of 40 bytes.

Answer

Leading zeros within any 16-bit hexadecimal block may be omitted, and the primary IPv6 header has a fixed size of 40 bytes.
Leading zeros within a 16-bit block can be safely omitted without changing the block's numeric value. Furthermore, the standard primary IPv6 header is simplified with a fixed size of 40 bytes to optimize routing lookup performance.

Step-by-Step Solution

1
Analyze zero suppression rules for 16-bit IPv6 hexadecimal fields.
Leading zeros inside a field (such as 0042) can be shortened to 42. Trailing zeros must remain intact to preserve the position and value of the digits.
Only leading zero suppression preserves the original numerical value of a nibble field.
2
Analyze the rule regarding double colon (::) compression.
A double colon represents consecutive all-zero blocks, but it can only appear once in an address.
If multiple double colons were permitted, a host would be unable to calculate the exact number of zero blocks belonging to each sequence.
3
Evaluate the structural specification of the main IPv6 header.
The standard base IPv6 header is fixed at 40 bytes in length.
A predictable fixed header length speeds up hardware switching and routing compared to IPv4's variable header length.

Key Concept

IPv6 Address Representation Rules and Primary Header Architecture
Estimated Time:1m 0s
Question 348Question →

Match each OSI reference model layer on the left with its core function on the right.

Click a left item, then click its matching right item

Items

Layer 2 - Data Link Layer
Layer 3 - Network Layer
Layer 4 - Transport Layer
Layer 7 - Application Layer

Matches

Show answer & explanation

Answer

The Data Link layer (Layer 2) matches MAC addressing and local frame delivery; the Network layer (Layer 3) matches logical IP addressing and packet routing; the Transport layer (Layer 4) matches end-to-end connection management and port numbers; and the Application layer (Layer 7) matches direct interfacing with end-user software.
Each OSI model layer performs distinct functions: Layer 2 uses MAC addresses for local frame delivery; Layer 3 manages logical IP addresses for network routing; Layer 4 handles end-to-end delivery using TCP/UDP port numbers; and Layer 7 enables network interaction for user applications.

Step-by-Step Solution

1
Identify the primary function of Layer 2 (Data Link).
Layer 2 uses physical MAC addresses and frames for local node communication.
Hardware addressing and framing are core Data Link responsibilities.
2
Identify the primary function of Layer 3 (Network).
Layer 3 utilizes logical IP addresses to route packets between disparate networks.
Inter-network routing requires logical network addressing at Layer 3.
3
Identify the primary function of Layer 4 (Transport).
Layer 4 uses port numbers to segment data and manage end-to-end process delivery.
Process-to-process communication and flow control operate at Layer 4.
4
Identify the primary function of Layer 7 (Application).
Layer 7 provides standard network protocol interfaces for software applications.
High-level user network processes operate at the top of the OSI stack.

Key Concept

OSI Layer Functions and Responsibilities
Question 349Question →

A network administrator is deploying a real-time environmental sensor telemetry application across a corporate subnet. The application requires low-latency transmission of periodic status readings where lost updates are immediately superseded by newer readings and do not require retransmission. Which transport layer protocol characteristic best satisfies these operational requirements?

Show answer & explanation

Answer: User Datagram Protocol (UDP) due to its connectionless overhead structure and lack of delivery acknowledgment mechanisms.

Answer

User Datagram Protocol (UDP) due to its connectionless overhead structure and lack of delivery acknowledgment mechanisms.
User Datagram Protocol (UDP) is a connectionless transport protocol that operates without establishing a prior session, maintaining state, or performing error recovery. Because real-time telemetry updates are frequent and superseded by subsequent readings, UDP's minimal header overhead and lack of retransmission delay make it the optimal choice.

Step-by-Step Solution

1
Identify the application requirements specified in the scenario.
The application requires low latency, minimal overhead, and can tolerate dropped packets without retransmission.
Real-time streaming and telemetry applications prioritize immediate data arrival over complete data recovery.
2
Evaluate transport layer protocols against these requirements.
UDP operates without a connection handshake, sequence numbers, or acknowledgment mechanisms.
Connectionless protocols eliminate the latency associated with session setup and automatic retransmission of lost packets.
3
Select the protocol characteristic that matches the requirement.
UDP provides connectionless transmission ideal for latency-sensitive telemetry.
TCP would introduce latency through flow control and retransmissions, while IP operates at Layer 3 rather than Layer 4.

Key Concept

Connection-Oriented vs Connectionless Protocols
Estimated Time:1m 0s
Question 350Question →

A network engineer is observing the convergence process of an OSPF network after a core router interface experiences a sudden link loss. Arrange the events of link-state convergence into the correct chronological order from first to last.

Drag items to arrange them in the correct order

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Answer

The correct chronological sequence of OSPF convergence events is: 1) Physical link failure detection, 2) LSA generation and flooding, 3) Neighbor LSDB update, 4) Dijkstra's SPF algorithm recalculation, and 5) RIB/Routing table path updates.
The convergence process in link-state protocols follows a strict operational order: local failure detection occurs first, followed by LSA creation and flooding to communicate the failure. Next, receiving routers update their local LSDB map, execute Dijkstra's SPF algorithm on the updated database to determine new optimal paths, and finally update the Routing Information Base (RIB) with the newly computed routes.

Step-by-Step Solution

1
Identify the initial trigger event for link-state convergence.
The local router detects a link failure on an active interface.
Network convergence cannot start until a hardware or protocol-level failure is detected by the router.
2
Determine how topology changes are communicated across the OSPF area.
The router constructs an updated LSA and floods it to adjacent neighbors.
Link-state dynamic routing protocols rely on flooding LSAs so every router in an area has accurate topology information.
3
Trace the database update process on receiving routers.
Adjacent routers update their local Link-State Database (LSDB).
Routers must synchronize their database entries before calculating new paths.
4
Identify the path calculation algorithm executed after database synchronization.
Routers execute Dijkstra's Shortest Path First (SPF) algorithm.
Link-state protocols require running the SPF algorithm against the updated LSDB map to find the lowest-cost paths.
5
Finalize path installation into the routing table.
The new best paths are written into the Routing Information Base (RIB).
Packet forwarding decisions rely on the RIB, which is updated only after SPF computation completes.

Key Concept

OSPF Link-State Convergence Sequence and SPF Calculation
Estimated Time:1m 30s
Question 351Question →

A network administrator is conducting a comprehensive protocol audit across an enterprise infrastructure to ensure proper layer delegation. Match each specific operational network responsibility on the left to the corresponding layer of the Open Systems Interconnection (OSI) reference model on the right where that process primarily operates.

Click a left item, then click its matching right item

Items

Negotiating data syntax, converting character encodings (such as ASCII to EBCDIC), and executing data compression or payload encryption.
Establishing, maintaining, and terminating logical dialogues between applications, including inserting synchronization checkpoints for session recovery.
Segmenting upper-layer data payloads, reassembling out-of-order sequence numbers, and enforcing sliding window flow control.
Encapsulating network layer packets into discrete frames, managing physical node addressing via MAC addresses, and performing CRC error detection.

Matches

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Answer

Data syntax negotiation, character encoding conversion, and payload encryption correspond to the Presentation Layer (Layer 6). Dialogue management and synchronization checkpoints correspond to the Session Layer (Layer 5). Data segmentation, sequence numbering, and sliding window flow control correspond to the Transport Layer (Layer 4). Frame encapsulation, MAC addressing, and CRC error detection correspond to the Data Link Layer (Layer 2).
Each operation correctly maps to its distinct OSI layer responsibility. The Presentation Layer (Layer 6) formats and encrypts data. The Session Layer (Layer 5) maintains dialogue checkpoints and session state. The Transport Layer (Layer 4) executes segmentation and flow control. The Data Link Layer (Layer 2) governs frame construction, MAC addressing, and local bit integrity verification.

Step-by-Step Solution

1
Analyze the first operational task: data syntax negotiation, character encoding conversion, and payload encryption.
Identify that data translation and encryption are key responsibilities of Layer 6.
Layer 6 (Presentation Layer) ensures data formatting is compatible between transmitting and receiving entities.
2
Analyze the second operational task: establishing and terminating application dialogues and managing synchronization checkpoints.
Identify dialogue control and checkpointing as functions of Layer 5.
Layer 5 (Session Layer) coordinates multi-packet conversations and provides resumption mechanisms in case of network disruptions.
3
Analyze the third operational task: segmenting data streams, ordering sequence numbers, and managing sliding window flow control.
Identify transport mechanisms operating at Layer 4.
Layer 4 (Transport Layer, e.g., TCP) ensures host-to-host reliability, sequence reassembly, and dynamic buffer management.
4
Analyze the fourth operational task: frame encapsulation, MAC address control, and CRC error detection.
Identify physical-adjacent node-to-node framing mechanisms operating at Layer 2.
Layer 2 (Data Link Layer) manages node-to-node transfer across local media using MAC addresses and trailer checksums.

Key Concept

OSI Reference Model Layer Functions and Responsibilities
Question 352Question →

A network administrator is designing an IPv4 addressing scheme for a security monitoring VLAN that must support 3131 dedicated IP cameras, each requiring a static usable IPv4 address. Which CIDR prefix length represents the smallest subnet block that accommodates all required cameras while conserving address space?

Show answer & explanation

Answer: /26/26

Answer

The prefix /26/26 is the correct choice because it provides 6262 usable host IP addresses, satisfying the requirement for 3131 cameras with minimal address waste.
The prefix /26/26 allocates 66 host bits, providing 26−2=622^6 - 2 = 62 usable host IP addresses. This is the smallest standard IPv4 subnet that accommodates 3131 devices without exhausting available addresses.

Step-by-Step Solution

1
Determine the required number of usable host IP addresses
The network must support at least 3131 usable host IP addresses.
Each IP camera requires its own individual static usable IPv4 address.
2
Calculate usable host capacity using the formula 2h−2≥312^h - 2 \ge 31
For h=5h = 5 host bits, 25−2=302^5 - 2 = 30 usable hosts (insufficient). For h=6h = 6 host bits, 26−2=622^6 - 2 = 62 usable hosts (sufficient).
Two IP addresses in every IPv4 subnet are reserved for the network ID and broadcast address and cannot be assigned to host interfaces.
3
Convert host bits to CIDR prefix length
Prefix length =32−6=/26= 32 - 6 = /26.
An IPv4 address consists of 3232 total bits, so subtracting the 66 host bits leaves 2626 prefix bits.

Key Concept

Subnet Usable Host Calculation
Estimated Time:1m 30s
Question 353Question →

A network security technician is auditing stateless firewall access control lists (ACLs) to enforce the principle of least privilege for specific enterprise infrastructure services. Match each network service requirement on the left with its corresponding protocol, transport layer protocol, and default port number configuration on the right.

Click a left item, then click its matching right item

Items

Encrypted remote console management and interactive secure file transfers (SFTP)
Secure directory service authentication queries over an SSL/TLS tunnel
Encrypted remote retrieval and synchronization of email messages while retaining server copies
Automated IP address assignment and host configuration across subnets via relay agents

Matches

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Answer

Encrypted remote console management (SFTP) matches SSH/SFTP over TCP port 22. Secure directory authentication matches LDAPS over TCP port 636. Encrypted email synchronization preserving server copies matches IMAPS over TCP port 993. Automated dynamic IP configuration matches DHCP over UDP ports 67 and 68.
Each service requirement maps precisely to its standard well-known port, transport layer protocol, and security profile: SFTP/SSH on TCP 22, LDAPS on TCP 636, IMAPS on TCP 993, and DHCP on UDP 67/68.

Step-by-Step Solution

1
Identify the protocol and port requirement for secure CLI/file transfer.
SFTP operates within SSH, utilizing connection-oriented TCP on port 22.
SSH protocol handles shell sessions, SCP, and SFTP over a single encrypted channel.
2
Determine the secure directory access protocol and port.
LDAP Secure (LDAPS) uses TCP port 636.
Standard unencrypted LDAP runs on TCP 389, while SSL/TLS wrapper defaults to port 636.
3
Identify the encrypted email retrieval protocol that keeps messages on the server.
IMAPS uses TCP port 993.
IMAP keeps emails synchronized on the server (unlike POP3) and IMAPS secures this communication on port 993.
4
Analyze transport type and ports for automated host IP addressing.
DHCP uses connectionless UDP on ports 67 and 68.
DHCP servers listen on UDP port 67 and clients receive responses on UDP port 68 during the DORA process.

Key Concept

Common Application Layer Protocols, Transport Layer Selection (TCP vs UDP), and Secure Port Mappings
Question 354Question →

A web server receives an incoming Ethernet frame carrying an HTTPS request over TLS/TCP. Arrange the following de-encapsulation steps performed by the receiving host network stack in the correct chronological sequence from first (bottom of stack) to last (top of stack).

Drag items to arrange them in the correct order

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Answer

The correct sequence of de-encapsulation is: 1) NIC validates FCS and strips Ethernet header/trailer (Layer 2 frame to Layer 3 packet); 2) Network layer verifies destination IP and strips IPv4 header (Layer 3 packet to Layer 4 segment); 3) Transport layer processes port numbers and strips TCP header (Layer 4 segment to upper-layer data); 4) TLS layer decrypts the encrypted payload (Layer 5/6 Presentation layer processing); 5) Web server process parses the HTTP request (Layer 7 Application layer).
De-encapsulation operates strictly bottom-up (Layer 2 frame → Layer 3 packet → Layer 4 segment → Layer 5/6 decrypted session → Layer 7 application data). At each step, a device inspects its specific layer control header, verifies checksums/integrity, strips the header/trailer, and uses higher-layer protocol indicators (EtherType, IP Protocol field, TCP Port) to pass the remaining PDU up to the next layer.

Step-by-Step Solution

1
Identify Data Link Layer (Layer 2) de-encapsulation
Ethernet frame header and trailer (FCS) are stripped by the NIC upon integrity verification, leaving an IP packet.
De-encapsulation always starts at the lowest layer (Layer 1/2) when receiving signals off the physical wire.
2
Identify Network Layer (Layer 3) de-encapsulation
Destination IP address is checked and the IPv4 header is stripped, leaving a TCP segment.
Layer 3 processing evaluates IP headers and uses the Protocol field (TCP=6) to direct the packet payload to the correct Layer 4 protocol engine.
3
Identify Transport Layer (Layer 4) de-encapsulation
TCP destination port (e.g., 443) is evaluated, sequence numbers are reassembled, and the TCP header is stripped.
Layer 4 uses port numbers to multiplex data streams to specific application sockets.
4
Identify Presentation/Session Layer (Layer 5/6) security unwrapping
TLS cryptographic records are decrypted to reveal the raw HTTP request text.
Decryption must occur after Layer 4 TCP segment reassembly completes, but before the HTTP application daemon can interpret the request syntax.
5
Identify Application Layer (Layer 7) execution
The web server application reads the raw HTTP GET request.
The top of the OSI stack processes pure application payload free of all transport, network, framing headers, and encryption layers.

Key Concept

Inbound De-encapsulation Sequence and PDU Unwrapping
Question 355Question →

An enterprise organization with 8 branch locations is migrating its site-to-site connectivity from a legacy dedicated full-mesh physical WAN to a Dynamic Multipoint VPN (DMVPN) deployment featuring redundant dual central hubs over commercial internet links. Which of the following statements accurately describe the topological changes and operational characteristics resulting from this migration? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: The physical topology shifts to a dual-hub-and-spoke model reducing static WAN connections from 28 to 16, while the logical topology can dynamically establish direct spoke-to-spoke tunnels on demand.; The virtual overlay operates logically as a non-broadcast multi-access (NBMA) network, requiring encapsulation protocols like Multipoint GRE to transport multicast routing protocol traffic across internet transports.

Answer

The physical topology shifts to a dual-hub-and-spoke model reducing static WAN connections from 28 to 16 while supporting dynamic logical spoke-to-spoke tunnels, and the virtual overlay functions as an NBMA network requiring mGRE to carry multicast and broadcast traffic.
Migrating from a static full-mesh WAN to a dual-hub DMVPN architecture changes the physical connection count from 28 static links (calculated via N(N−1)2\frac{N(N-1)}{2} for 8 nodes) down to 16 static hub links (8 sites×2 hubs8 \text{ sites} \times 2 \text{ hubs}). Furthermore, public internet transport functions logically as an NBMA network, requiring encapsulation like Multipoint GRE (mGRE) to handle broadcast and multicast traffic for dynamic routing protocols.

Step-by-Step Solution

1
Calculate physical WAN link requirements for full mesh versus dual hub-and-spoke.
Full mesh for N=8N=8 sites requires 8(8−1)2=28\frac{8(8-1)}{2} = 28 physical links. Dual-hub topology requires each of the 8 sites to connect to 2 hubs, totaling 8×2=168 \times 2 = 16 static hub-spoke links.
Topological transition reduces static provisioning overhead while using dynamic overlay capabilities.
2
Analyze logical overlay capabilities of DMVPN.
DMVPN combines Multipoint GRE (mGRE) and Next Hop Resolution Protocol (NHRP) to dynamically establish temporary spoke-to-spoke tunnels across an NBMA internet transport.
This allows direct spoke communication without static full-mesh tunnel configuration or permanent routing through central hubs.

Key Concept

Physical vs. Logical Topologies and DMVPN Overlay Mechanics
Question 356Question →

Match each IPv6 address type or field name on the left with its corresponding prefix or functional description on the right.

Click a left item, then click its matching right item

Items

Global Unicast Address
Link-Local Address
Multicast Address
Loopback Address

Matches

Show answer & explanation

Answer

Global Unicast Address matches 2000::/3, Link-Local Address matches fe80::/10, Multicast Address matches ff00::/8, and Loopback Address matches ::1/128.
Global Unicast addresses start with 2000::/3, Link-Local addresses start with fe80::/10, Multicast addresses start with ff00::/8, and the Loopback address is represented by ::1/128.

Step-by-Step Solution

1
Identify the designated prefix block for each IPv6 address scope.
Global Unicast uses 2000::/3, Link-Local uses fe80::/10, Multicast uses ff00::/8, and Loopback uses ::1/128.
IPv6 standard address allocation defines specific prefix ranges to separate unicast, multicast, link-restricted, and host-internal operations.

Key Concept

IPv6 Address Scopes and Prefixes
Question 357Question →

Arrange the following Protocol Data Units (PDUs) in the correct sequential order as data moves down the Open Systems Interconnection (OSI) model during the encapsulation process, starting from the application layer down to the physical transmission medium.

Drag items to arrange them in the correct order

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Answer

The correct encapsulation sequence from top to bottom is: Data → Segment → Packet → Frame → Bits.
During encapsulation, data moves down the OSI model from Layer 7 to Layer 1. The PDU sequence is Data at the upper layers (Application, Presentation, Session), Segment at the Transport layer (Layer 4), Packet at the Network layer (Layer 3), Frame at the Data Link layer (Layer 2), and Bits at the Physical layer (Layer 1).

Step-by-Step Solution

1
Identify the starting point of data creation in the OSI model.
Information originates at the Application, Presentation, and Session layers as raw Data.
Encapsulation begins at the upper layers before being prepared for network transport.
2
Determine the PDU created at the Transport layer (Layer 4).
Data is segmented and wrapped with transport protocol headers to create Segments (or Datagrams).
Layer 4 manages end-to-end communication and port numbers.
3
Determine the PDU created at the Network layer (Layer 3).
Segments are encapsulated with IP headers containing source and destination IP addresses to create Packets.
Layer 3 handles logical addressing and path selection across networks.
4
Determine the PDU created at the Data Link layer (Layer 2).
Packets are encapsulated with MAC headers and frame check sequence trailers to create Frames.
Layer 2 facilitates node-to-node transfer on the local network segment.
5
Determine the final state at the Physical layer (Layer 1).
Frames are encoded into raw Bits for transmission across physical medium.
Layer 1 transmits binary signals over copper cables, fiber optics, or wireless mediums.

Key Concept

OSI Model Data Encapsulation and PDU Sequence
Question 358Question →

Match each switching concept on the left with its correct operational description on the right.

Click a left item, then click its matching right item

Items

802.1Q Tagging
Native VLAN
Access Port
Trunk Port

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Answer

802.1Q Tagging matches the standard 4-byte header insertion protocol; Native VLAN matches handling untagged traffic on trunk links; Access Port matches single-VLAN host connection mode; Trunk Port matches multi-VLAN inter-switch transport mode.
Each switching term correctly maps to its foundational Layer 2 behavior: 802.1Q tagging defines the 4-byte frame header, Native VLAN carries untagged frames over trunk links, Access ports assign an interface to a single VLAN for endpoints, and Trunk ports carry traffic across multiple VLANs between switches.

Step-by-Step Solution

1
Identify the protocol used for VLAN encapsulation across trunk links.
IEEE 802.1Q inserts a 4-byte field into the Ethernet frame header containing the VLAN ID.
802.1Q is the industry standard framing mechanism for preserving VLAN identity across switches.
2
Determine how untagged frames are processed on trunk interfaces.
Frames without an 802.1Q tag header passing over a trunk link are automatically assigned to the Native VLAN.
The Native VLAN provides backward compatibility for untagged legacy traffic and control protocols.
3
Distinguish between Access Port and Trunk Port operations.
Access ports strip tags and belong strictly to a single VLAN for end hosts, whereas Trunk ports retain tags to transport multiple VLANs simultaneously.
End-user devices do not inspect 802.1Q tags, so access ports deliver untagged frames to hosts while trunk ports multiplex tagged traffic between networking devices.

Key Concept

Switch Port Roles and IEEE 802.1Q VLAN Tagging
Question 359Question →

A network administrator connects two workstations, Host A and Host B, to access ports on the same physical Layer 2 switch. Host A is configured on VLAN 10 (192.168.10.0/24), while Host B is configured on VLAN 20 (192.168.20.0/24). Host A transmits an ARP broadcast frame to determine an IP address on its local network segment. How will the switch handle this broadcast frame?

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Answer: The switch floods the broadcast frame out all ports assigned to VLAN 10 except the receiving port, preventing Host B on VLAN 20 from receiving it.

Answer

The switch floods the broadcast frame out all ports assigned to VLAN 10 except the receiving port, preventing Host B on VLAN 20 from receiving it.
A Virtual Local Area Network (VLAN) creates a logical boundary at Layer 2. Broadcast frames transmitted by a device are flooded only to interfaces within the exact same VLAN membership (excluding the receiving interface). Consequently, Host B on VLAN 20 is shielded from VLAN 10 broadcast traffic.

Step-by-Step Solution

1
Identify the frame type and ingress interface configuration.
The incoming frame is an Ethernet broadcast frame (destination MAC FF:FF:FF:FF:FF:FF) originating from a host assigned to VLAN 10.
VLAN memberships assigned to switch interfaces define the boundary for Layer 2 broadcast containment.
2
Determine Layer 2 switch forwarding behavior for broadcast traffic within a VLAN.
The switch replicates the broadcast frame to all operational interfaces that belong to VLAN 10, excluding the port where the frame entered.
VLANs act as independent logical switches; frames in one VLAN are isolated from interfaces assigned to other VLANs.
3
Evaluate the impact on hosts in different VLANs.
Host B, residing on an access port configured for VLAN 20, does not receive the broadcast frame.
Without a Layer 3 routing mechanism (such as a router or Layer 3 switch), traffic cannot cross VLAN boundaries.

Key Concept

VLAN Broadcast Domain Isolation
Estimated Time:1m 15s
Question 360Question →

An edge router receives multiple exterior gateway protocol routes pointing to the same destination network prefix from different autonomous systems. Place the Border Gateway Protocol (BGP) path selection attributes in the correct order of evaluation from first to last.

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Answer

The correct order of evaluation for BGP path selection attributes from first to last is: Highest Local Preference, Shortest AS-Path length, Lowest Origin type, and Lowest Multi-Exit Discriminator (MED).
BGP path selection follows a deterministic hierarchy to pick the best path when multiple routes exist for a prefix. The evaluation begins with local attributes (Highest Local Preference), proceeds to path metric attributes (Shortest AS-Path length), checks route source reliability (Lowest Origin type), and finally compares entry points for neighboring systems (Lowest MED).

Step-by-Step Solution

1
Identify the primary outbound policy attribute.
Highest Local Preference is selected as the top criteria evaluated within an Autonomous System.
Local preference takes precedence over path length and origin characteristics to allow local administrators to override default routing decisions.
2
Evaluate path distance metric when local preferences are equal.
Shortest AS-Path length is evaluated second.
BGP prefers routes that cross fewer autonomous systems to minimize inter-domain transit latency.
3
Compare route origin source mechanism.
Lowest Origin type is evaluated third.
Routes created natively via internal routing protocols (IGP) are trusted more than external or unknown redistributed routes.
4
Determine path preference into neighbor autonomous systems.
Lowest Multi-Exit Discriminator (MED) is evaluated fourth.
MED acts as a tie-breaker when multiple entry points exist into the same neighboring autonomous system.

Key Concept

BGP Path Selection Algorithm Hierarchy
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