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Question 381

How are switch access ports assigned to specific VLANs?

1. switchport mode trunk
2. switchport access vlan [id]
3. vlan database active
4. spanning-tree portfast enable

Correct Answer: 2

Explanation:

Configuring a switch port to belong to a specific Virtual Local Area Network requires assigning it as an access port and binding it to a designated VLAN identification number using interface configuration commands. The command switchport access vlan [id] explicitly places the physical interface into access mode and maps untagged incoming traffic directly to the specified VLAN. Access ports are designed to connect end-user devices such as personal computers, IP printers, and servers that do not process 802.1Q frame tags. When traffic enters an access port, the switch internally associates it with the assigned VLAN, ensuring that broadcast domains remain logically segregated across the switching infrastructure without requiring separate physical switches for each workgroup or department.

Question 382

How does an OSPF router determine its default router ID?

1. Highest loopback IP address, then highest physical IP address.
2. Lowest MAC address configured on any active interface.
3. Automatically assigned sequentially by the active designated router.
4. Manually configured static string or highest priority value.

Correct Answer: 1

Explanation:

The Open Shortest Path First routing protocol requires a unique 32-bit Router ID to identify every participating router within an area network topology uniquely. During protocol initialization, the OSPF process selects its Router ID using a strict hierarchical preference order. First, if a router ID has been explicitly defined using the router-id command under the OSPF configuration mode, that value takes precedence. If no manual ID is configured, the router examines all active loopback interfaces, selecting the highest IPv4 address among them. If no loopback interfaces exist, the router evaluates all active physical interfaces, choosing the highest IPv4 address configured on any operational interface. If duplicate IDs exist, adjacencies fail.

Question 383

What qualifies an EIGRP neighbor as a valid feasible successor?

1. Its reported distance is greater than the local feasible distance.
2. Its reported distance is less than the local feasible distance.
3. Its total administrative distance is lower than static routes.
4. Its hop count is exactly equal to fifteen.

Correct Answer: 2

Explanation:

The Enhanced Interior Gateway Routing Protocol utilizes advanced loop-prevention mechanisms governed by the Diffusing Update Algorithm and the Feasibility Condition. A neighboring router qualifies as a Feasible Successor—representing a certified loop-free backup path—only if its Reported Distance (the metric advertised by the neighbor to the destination) is strictly less than the local router’s current Feasible Distance (the lowest total metric calculated to reach that destination). This mathematical condition ensures that the backup path does not loop back through the local router, allowing the network to switch instantly to the backup route during primary link failures without triggering slow diffusing computations.

Question 384

What parameter does Spanning Tree Protocol evaluate first during root bridge selection?

1. Switch port priority value
2. Bridge Priority in the Bridge ID
3. Interface bandwidth and link cost
4. Switch MAC address formatting

Correct Answer: 2

Explanation:

The Spanning Tree Protocol election process begins by selecting a single root bridge to serve as the logical center of the spanning tree topology. To determine which switch becomes the root bridge, all switches exchange Bridge Protocol Data Units containing their unique Bridge IDs. The Bridge ID consists of a configurable two-byte priority field combined with a six-byte base MAC address. The STP algorithm evaluates the Bridge Priority field first, selecting the switch advertising the lowest numerical priority value as the root bridge. If multiple switches share identical priority values, the algorithm breaks the tie by evaluating their MAC addresses, choosing the switch with the lowest MAC address.

Question 385

How do IPv6 hosts generate global unicast addresses automatically using SLAAC?

1. Requesting parameters dynamically from a stateful DHCPv6 server.
2. Combining a router-advertised prefix with an interface identifier derived via EUI-64 or random generation.
3. Broadcasting ARP requests across the local network segment.
4. Utilizing fixed static addresses hardcoded into NVRAM storage.

Correct Answer: 2

Explanation:

Stateless Address Autoconfiguration allows IPv6 hosts to configure operational global unicast IP addresses independently without relying on stateful DHCPv6 servers. When an interface initializes, it transmits a Router Solicitation message. In response, local routers broadcast Router Advertisement messages containing network prefix information. The host takes the received network prefix and combines it with a 64-bit interface identifier—either generated automatically using the IEEE EUI-64 standard based on its MAC address or created via random privacy extensions—to form a complete, globally unique IPv6 unicast address. This mechanism drastically simplifies IP address management in modern enterprise networks.

Question 386

What differentiates the restrict port security violation mode from shutdown?

1. Restrict drops unauthorized traffic and logs syslog warnings without disabling the port.
2. Restrict places the physical interface into an error-disabled state immediately.
3. Restrict automatically reconfigures the unauthorized device into the native VLAN.
4. Restrict shuts down the entire switch stack to protect core routing tables.

Correct Answer: 1

Explanation:

Cisco switch port security provides distinct violation modes to handle unauthorized endpoints connecting to secure ports. While the default shutdown mode places the physical interface into an error-disabled state requiring manual administrative intervention, the restrict mode takes a less disruptive approach. When a security violation occurs under restrict mode, the switch drops incoming traffic originating from unauthorized MAC addresses, increments violation counter statistics, and generates a syslog warning message alerting administrators to the security breach. However, the physical port remains active and operational, continuing to forward authorized traffic originating from pre-configured or dynamically learned secure MAC addresses.

Question 387

How does the TCP sliding window mechanism optimize data transmission efficiency?

1. By terminating idle sessions automatically after a preset timer expires.
2. By allowing the receiver to acknowledge multiple bytes and control transmission pacing dynamically.
3. By encrypting packet headers to prevent unauthorized interception.
4. By forcing both hosts to transmit data at fixed, immutable clock speeds.

Correct Answer: 2

Explanation:

The Transmission Control Protocol sliding window mechanism is a flow control method designed to maximize network throughput and prevent buffer overflows on receiving hosts. Instead of requiring an explicit acknowledgment after every single transmitted byte or packet, the sliding window allows the sending host to transmit multiple segments continuously up to a specified window size limit. The receiving host continuously updates its available buffer capacity—known as the window size—within acknowledgment headers. As acknowledgments arrive, the sender slides its transmission window forward, pacing data flow dynamically based on network congestion and receiver processing capabilities without halting transmission lines.

Question 388

What command enables a router to forward broadcast DHCP requests across different subnets?

1. ip routing
2. ip helper-address [ip-address]
3. ip nat inside source
4. router dhcp enable

Correct Answer: 2

Explanation:

Because Dynamic Host Configuration Protocol operates via broadcast communications during initial client discovery phases, routers normally drop these broadcast packets at network boundaries to prevent broadcast storms. To enable centralized DHCP servers to service clients residing across remote subnets, network engineers configure the ip helper-address [ip-address] command on the inbound Layer 3 interface facing the client segment. When the router intercepts a broadcast DHCP request, it converts the broadcast packet into a unicast packet, replacing the destination IP address with the pre-configured DHCP server IP address, and forwards it across routing boundaries to the destination server.

Question 389

What is the primary function of the virtual IP address configured in an HSRP group?

1. Serving as the default gateway IP address for client workstations.
2. Identifying the physical management interface of the standby router.
3. Encrypting routing protocol update packets across wide area links.
4. Establishing secure SSH administrative sessions.

Correct Answer: 1

Explanation:

The Hot Standby Router Protocol is a Cisco proprietary First Hop Redundancy Protocol designed to provide high availability for default gateway routing. HSRP groups multiple physical routers into a single logical router configuration sharing a common virtual IP address and virtual MAC address. Client workstations on the local network segment are configured with this virtual IP address as their static default gateway. If the active physical router fails, the standby router detects the loss of hello messages, assumes the active forwarding role seamlessly, and takes over responding to traffic destined for the shared virtual IP address, ensuring uninterrupted network connectivity.

Question 390

How do wildcard masks function within standard IPv4 Access Control Lists?

1. Matching exact binary bits where zeros represent strict matching and ones represent ignored bits.
2. Defining exact subnet prefix lengths using slash notation.
3. Encrypting packet payloads using symmetric cryptographic keys.
4. Limiting maximum transmission unit sizes across serial links.

Correct Answer: 1

Explanation:

Wildcard masks utilized in Cisco Access Control Lists are 32-bit binary numbers paired with IP addresses to determine which parts of an address to inspect. Unlike subnet masks where binary ones represent network bits, wildcard masks utilize inverted logic: a binary 0 indicates that the corresponding IP address bit must match exactly (strict matching), while a binary 1 indicates that the corresponding bit is ignored or treated as a wildcard. For example, a wildcard mask of 0.0.0.255 instructs the router to strictly match the first three octets of an IP address while ignoring any variations within the final host octet.

Question 391

Which Syslog severity level corresponds to an emergency system condition?

1. Level 0
2. Level 3
3. Level 5
4. Level 7

Correct Answer: 1

Explanation:

Syslog severity levels follow a standardized numerical scale ranging from 0 to 7, where lower numbers indicate catastrophic system failures requiring immediate administrative intervention. Level 0 corresponds to “Emergency” (logged as emerg), indicating that the system is entirely unusable and experiencing critical kernel failures. The complete hierarchical scale progresses from Level 0 (Emergency), Level 1 (Alert), Level 2 (Critical), Level 3 (Error), Level 4 (Warning), Level 5 (Notice), Level 6 (Informational), up to Level 7 (Debugging). Monitoring emergency logs ensures that network engineers can respond instantly to total infrastructural collapses.

Question 392

Which modern wireless authentication method replaces pre-shared keys with Simultaneous Authentication of Equals to prevent offline dictionary attacks?

1. WEP
2. WPA2-Personal
3. WPA3-Personal
4. WPS

Correct Answer: 3

Explanation:

Wi-Fi Protected Access 3 introduces advanced cryptographic protocols to secure wireless local area networks against evolving cyber threats. WPA3-Personal replaces the vulnerable pre-shared key exchange mechanism utilized in WPA2 with Simultaneous Authentication of Equals. SAE is a secure cryptographic handshake protocol based on elliptic-curve cryptography that authenticates users while protecting network connections against offline dictionary attacks, even if users select weak, easily guessable text passwords. Furthermore, WPA3 provides forward secrecy, ensuring that encrypted historical traffic sessions cannot be decrypted even if an attacker compromises the primary network password at a later date.

Question 393

What EtherChannel load-balancing method hashes both source and destination MAC addresses?

1. src-mac
2. dst-mac
3. src-dst-mac
4. src-ip

Correct Answer: 3

Explanation:

EtherChannel link aggregation bundles multiple physical Ethernet links into a single logical interface to increase total bandwidth and provide redundancy. To distribute traffic efficiently across the member links without causing out-of-order packet delivery, switches utilize hashing algorithms based on traffic header fields. Configuring the load-balancing method as src-dst-mac instructs the switch algorithm to evaluate both the source MAC address and destination MAC address of incoming frames, applying an exclusive-OR hashing calculation to select which physical link in the EtherChannel bundle will forward the frame, ensuring balanced traffic distribution across links.

Question 394

What does a Network Time Protocol Stratum 1 server connect to directly?

1. Client workstation personal computers
2. Authoritative Stratum 0 hardware reference clocks
3. Secondary edge distribution routers
4. Local network switch management ports

Correct Answer: 2

Explanation:

Network Time Protocol utilizes a hierarchical system of clock sources organized into numbered strata to distribute accurate timekeeping data across enterprise networks. Stratum 0 devices comprise authoritative, highly accurate physical clock hardware such as atomic cesium clocks, GPS satellite receivers, or radio clock transmitters. Stratum 1 servers are directly attached to these Stratum 0 physical reference sources via dedicated serial or high-speed hardware connections. Each subsequent stratum level represents a hop away from the primary source, ensuring precise time synchronization propagation across routers, switches, and firewalls throughout the enterprise network infrastructure.

Question 395

Which IPv4 address blocks are designated as private according to RFC 1918?

1. 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16
2. 192.0.2.0/24, 198.51.100.0/24, and 203.0.113.0/24
3. 127.0.0.0/8 and 169.254.0.0/16
4. 224.0.0.0/4 and 240.0.0.0/4

Correct Answer: 1

Explanation:

To conserve the rapidly depleting pool of public IPv4 addresses, RFC 1918 defines specific private IP address blocks that can be utilized freely within internal enterprise networks without registering with internet registries. These designated ranges include 10.0.0.0 through 10.255.255.255 (a /8 prefix), 172.16.0.0 through 172.31.255.255 (a /12 prefix), and 192.168.0.0 through 192.168.255.255 (a /16 prefix). Routers across the public internet are programmed to drop packets originating from or destined to these private address ranges, requiring organizations to implement Network Address Translation at network borders for external connectivity.

Question 396

Which SNMP version introduced robust authentication, message integrity, and cryptographic encryption for network management?

1. SNMPv1
2. SNMPv2c
3. SNMPv3
4. RMONv2

Correct Answer: 3

Explanation:

Simple Network Management Protocol Version 3 was developed to address the severe security vulnerabilities inherent in legacy SNMPv1 and SNMPv2c protocols, which transmitted community strings and management telemetry in clear text across networks. SNMPv3 introduces a robust security model incorporating user-based security modules to provide three essential security services: message integrity (ensuring packets are not tampered with in transit), authentication (verifying the identity of the management entity), and cryptographic encryption (protecting sensitive management data against eavesdropping). These security enhancements make SNMPv3 suitable for managing enterprise infrastructure securely.

Question 397

What is the operational purpose of an ICMP Redirect message?

1. Informing a host that a better routing path exists for its destination.
2. Reporting that a destination IP network is completely unreachable.
3. Testing basic end-to-end round-trip transmission latency.
4. Requesting physical hardware MAC address resolution.

Correct Answer: 1

Explanation:

An ICMP Redirect message is an error notification transmitted by a router to a host on the same local network segment when the router perceives that the host is utilizing a suboptimal gateway to reach a destination. For example, if a host transmits a packet to Router A, but Router A knows that Router B on the same local segment possesses a more direct path to the destination, Router A forwards the packet to its proper destination while simultaneously sending an ICMP Redirect message back to the sending host. This message instructs the host to update its routing table to bypass Router A and route subsequent traffic directly through Router B.

Question 398

Which OSPF area type blocks external summary and autonomous system external LSAs while injecting a default route?

1. Stub area
2. Transit area
3. Backbone area

Correct Answer: 2

Explanation:

The Open Shortest Path First routing protocol supports specialized area configurations to optimize routing table sizes and reduce memory overhead on internal routers. A stub area is an OSPF area configured to block flooding of Type 4 (Autonomous System Boundary Router summary) and Type 5 (Autonomous System External) link-state advertisements originating from outside the area. To ensure internal routers within the stub area can still reach external destinations without storing exhaustive external routing tables, the area’s internal Area Border Router automatically injects a default route (destined for 0.0.0.0/0) into the stub area using a Type 3 summary link-state advertisement.

Question 399

Which RSTP port state combines both listening and blocking functions to streamline convergence?

1. Forwarding
2. Learning
3. Discarding
4. Disabled

Correct Answer: 3

Explanation:

The Rapid Spanning Tree Protocol simplifies legacy 802.1D port states by consolidating blocking, listening, and disabled states into a single operational state known as Discarding. In the Discarding state, switch ports do not forward user data frames or populate their content-addressable memory tables with MAC addresses, but they continue to process incoming Bridge Protocol Data Units to monitor topology changes. By streamlining port states into Discarding, Learning, and Forwarding, RSTP eliminates legacy forwarding delays and achieves rapid network convergence within milliseconds during topology changes.

Question 400

What configuration register value instructs a Cisco router to bypass startup configuration files during booting?

1. 0x2100
2. 0x2102
3. 0x2120
4. 0x2142

Correct Answer: 4

Explanation:

The Cisco configuration register is a 16-bit software register stored in non-volatile random-access memory that controls router boot behavior. Under normal operational conditions, the register is set to 0x2102, instructing the router to load the system image from flash memory and load the saved startup configuration file into active RAM. During password recovery procedures, network technicians temporarily modify this register value to 0x2142. This hexadecimal value instructs the bootstrap loader to ignore and bypass the saved startup configuration file entirely during system initialization, allowing administrative access to the command-line interface without entering a password.