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2237 questions

Question 1681Question

A network administrator is evaluating dynamic routing protocol characteristics for an enterprise LAN deployment. Which of the following operational features are specific to link-state routing protocols such as OSPF when compared to distance-vector routing protocols? (Select TWO.)

Select all that apply

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Answer: Routers build and maintain a complete network topology map in a centralized or local Link-State Database (LSDB).; Routing update messages are triggered and flooded only when a state change occurs on a link.

Answer

Link-state protocols maintain a full network topology map in a Link-State Database (LSDB) and use event-driven triggered updates when link status changes occur.
Link-state protocols require routers to accumulate a complete view of the network topology inside a Link-State Database (LSDB) and use triggered LSA updates whenever network interface states change.

Step-by-Step Solution

1
Analyze link-state topology mapping.
Link-state routers collect Link-State Advertisements (LSAs) to build an identical map of the entire network area in their Link-State Database (LSDB).
This complete visibility allows the Shortest Path First (SPF) algorithm to calculate optimal loop-free paths.
2
Evaluate routing update transmission methods.
Link-state protocols issue differential updates only when a link state changes, rather than continuously transmitting the entire routing table.
Triggered updates minimize unnecessary bandwidth consumption and speed up network convergence.

Key Concept

Link-State vs Distance-Vector Routing Protocol Characteristics
Question 1682Question

A network technician is auditing a telecommunications enclosure and updating the facility's physical rack elevation diagrams. Which of the following information types should be included on a rack elevation diagram? (Select TWO.)

Select all that apply

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Answer: The exact vertical rack unit slot location where each device is mounted; The total physical height footprint (measured in rack units) of each mounted appliance

Answer

Physical rack elevation diagrams must include the exact vertical rack unit slot location of each mounted device and the physical height footprint (in rack units) of each appliance.
Physical rack elevation diagrams are scale drawings showing the front and rear views of equipment racks. They explicitly document physical characteristics such as the exact vertical unit slot placement (UU-position) and the height of each mounted component (such as 1U1\text{U} or 2U2\text{U} switches and servers) to assist with capacity planning, thermal management, and physical maintenance.

Step-by-Step Solution

1
Identify the primary purpose of a rack elevation diagram.
Recognize that rack elevation diagrams represent the physical layout and vertical space allocation within a server or equipment rack.
Rack diagrams focus specifically on hardware placement, space availability, power allocation, and cabinet layout.
2
Evaluate the choices to distinguish physical rack attributes from logical network attributes.
The vertical slot placement and the height in rack units directly pertain to physical rack planning.
Logical attributes like virtual IP addresses, wireless channel plans, and protocol data units belong in logical topology, IPAM, or wireless survey documentation.

Key Concept

Physical Rack Elevation Diagrams
Question 1683Question

A client host connected to VLAN 20 requires an IPv4 address lease from a centralized DHCP server located on VLAN 10. The router acting as the default gateway for VLAN 20 is configured with a DHCP relay agent. What is the correct chronological sequence of network events during the initial discovery and offer process?

Drag items to arrange them in the correct order

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Answer

The process begins when the client broadcasts a DHCPDISCOVER packet on VLAN 20 (item 1). The Layer 3 router interface on VLAN 20 intercepts the broadcast (item 2). Next, the relay agent populates the giaddr field with its own interface address and forwards the request as a unicast packet to the DHCP server on VLAN 10 (item 3). The DHCP server reads the giaddr, allocates an IP from the VLAN 20 pool, and unicasts a DHCPOFFER back to the relay agent (item 4). Finally, the relay agent transmits the DHCPOFFER onto VLAN 20 for the client host (item 5).
The correct order follows the standard DHCP relay packet flow across Layer 3 boundaries. The process starts with a local client broadcast on VLAN 20, followed by interception by the router interface relay agent. The relay agent sets its local IP in the giaddr field and unicasts the packet to the DHCP server on VLAN 10. The server uses the giaddr to select the VLAN 20 scope and unicasts a DHCPOFFER back to the relay agent, which delivers it onto VLAN 20 for the client.

Step-by-Step Solution

1
Identify the initial client-generated broadcast packet.
The client emits a broadcast DHCPDISCOVER on UDP port 67 within VLAN 20.
Unconfigured hosts must broadcast locally to find available DHCP servers or relay agents.
2
Identify Layer 3 gateway interception.
The router interface (acting as relay agent) traps the broadcast frame on VLAN 20.
Routers drop broadcast packets by default unless a DHCP relay feature (such as ip helper-address) is configured.
3
Determine relay packet modification and unicast forwarding.
The router sets the giaddr header field to its VLAN 20 IP address and unicasts the packet across routed links to the server IP on VLAN 10.
The giaddr field informs the remote server which IP subnet scope to assign from.
4
Determine server processing and response generation.
The DHCP server selects a VLAN 20 lease scope based on giaddr and unicasts a DHCPOFFER back to the relay agent's giaddr address.
The server responds via unicast to the relay agent gateway.
5
Complete relay forwarding to the requesting client.
The relay agent receives the server's unicast DHCPOFFER and relays it onto VLAN 20 to the client host.
The client receives the offered IP configurations on its local Layer 2 network segment.

Key Concept

DHCP Relay Agent Operational Sequence and giaddr Field Insertion
Question 1684Question

A network engineering team is restructuring its operational repository to streamline incident resolution and infrastructure planning. Match each network documentation artifact on the left with the operational scenario on the right where it serves as the primary technical reference.

Click a left item, then click its matching right item

Items

Logical Network Diagram with IPAM Mapping
Physical Rack Elevation Diagram with PDU Circuit Layout
Wiring Schematic and Cable Run Schedule
Network Baseline and Traffic Metric Report

Matches

Show answer & explanation

Answer

Logical diagrams correlate with Layer 3 routing and IP gateway troubleshooting; Rack elevation diagrams correlate with physical hardware placement, vertical space (UU), and power load planning; Wiring schematics correlate with Layer 1 cable run pinout tracing; Network baselines correlate with performance anomaly detection against historical metrics.
Each documentation type serves a specific function in network management: logical diagrams depict software structures and Layer 3 boundaries; physical rack elevations depict hardware chassis mounting and power feeds; wiring schematics detail copper/fiber pinouts and physical patch paths; and baselines record statistical performance benchmarks.

Step-by-Step Solution

1
Analyze the operational requirements involving subnets, IPAM data, and VRRP/HSRP gateway redundancy.
Determine that logical network topology diagrams contain the necessary Layer 3 IP addressing and routing structure.
Logical diagrams represent protocol relationships and network layer boundaries independently of physical hardware locations.
2
Analyze physical enclosure constraints including vertical unit height (UU), heat generation, and PDU electrical circuit balance.
Determine that physical rack elevation diagrams provide exact spatial and electrical layout mapping.
Rack elevation diagrams explicitly render 19-inch equipment racks, unit space reservations, and power supply feeds.
3
Analyze physical Layer 1 media tracing tasks requiring cable pinout (T568B) and patch panel port isolation.
Determine that wiring schematics and cable run schedules provide line-item cross-connect mappings.
Cable schedules catalog jack IDs, termination blocks, cable types, and color-code standards from end-point to IDF.
4
Analyze performance measurement tasks evaluating bandwidth utilization trends and latency variations.
Determine that network baselines establish the reference dataset needed for comparative analysis.
Baselines document normal operational parameters (throughput, CPU usage, error rates) over defined historical periods.

Key Concept

Operational Purpose of Network Documentation Artifacts
Estimated Time:2m 0s
Question 1685Question

During an infrastructure security audit of a enterprise cloud network, a network engineer discovers that virtual machines residing in separate IP subnets can communicate directly without traversing the perimeter firewall. To trace the virtual routing tables, interface IP addressing, VLAN IDs, and logical security zone boundaries across the environment regardless of underlying hardware server placement, which of the following documentation artifacts should the engineer consult first?

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Answer: Logical network diagram

Answer

Logical network diagram
Logical network diagrams document how data moves through a network by displaying subnets, IP addressing schemes, VLAN IDs, virtual routing instances, and security zones. This makes them the primary reference for troubleshooting logical routing anomalies across physical or virtual boundaries.

Step-by-Step Solution

1
Identify the primary requirement of the scenario
The engineer needs to trace IP subnets, VLAN IDs, virtual routing tables, and security boundaries across virtualized infrastructure.
Resolving unauthorized cross-subnet communication requires analyzing Layer 2 and Layer 3 logical structures.
2
Evaluate documentation types against the requirement
Physical network diagrams, rack elevations, and wiring schematics document Layer 1 physical attributes (hardware placement, cabling, rack U-height).
Only logical network diagrams map IP addressing, subnets, virtual interfaces, and security zones.
3
Select the correct documentation artifact
The logical network diagram is the appropriate artifact.
It provides the high-level and detailed logical topology required to pinpoint misconfigured virtual routing paths.

Key Concept

Logical Network Topology Documentation
Question 1686Question

A network architect is performing a spectral audit of a high-density warehouse deployment operating in the 2.4 GHz ISM band. The physical installation consists of five adjacent access points (APs) mounted on a single high-ceiling beam line. The current channel configuration assigns the APs to channels 1, 3, 6, 8, and 11 with equal transmit power. Which statement accurately identifies the primary issue with this channel plan and its operational impact on the wireless network?

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Answer: Channels 3 and 8 overlap with adjacent channels 1, 6, and 11, causing severe adjacent-channel interference (ACI) and frame corruption because overlapping signals cannot be decoded or coordinated by CSMA/CA.

Answer

Channels 3 and 8 overlap with adjacent channels 1, 6, and 11, causing severe adjacent-channel interference (ACI) and frame corruption because overlapping signals cannot be decoded or coordinated by CSMA/CA.
The correct option highlights that in the 2.4 GHz band, each 20 MHz channel overlaps with adjacent channel numbers due to 5 MHz center-frequency spacing. The only non-overlapping 3-channel plan in North America uses channels 1, 6, and 11. Inserting channels 3 and 8 creates adjacent-channel interference (ACI), which disrupts CSMA/CA carrier sensing and leads to high packet corruption and retries.

Step-by-Step Solution

1
Analyze the frequency structure of the 2.4 GHz Wi-Fi spectrum.
Each standard 802.11 2.4 GHz channel occupies 20 MHz of bandwidth, but channel center frequencies are spaced only 5 MHz apart.
Understanding channel width vs channel spacing establishes why channels 1, 6, and 11 are the only 3 non-overlapping 20 MHz channels in North America.
2
Evaluate the impact of assigning channels 3 and 8 alongside channels 1, 6, and 11.
Channel 3 overlaps partially with both channel 1 and channel 6. Channel 8 overlaps partially with both channel 6 and channel 11.
Partial spectral overlap prevents wireless stations from correctly decoding preambles from adjacent APs, causing CSMA/CA clear channel assessment (CCA) to treat the overlapping energy as non-Wi-Fi noise/interference rather than manageable Wi-Fi frames.
3
Differentiate between Co-Channel Interference (CCI) and Adjacent-Channel Interference (ACI).
CCI allows devices to share airtime via CSMA/CA backoff algorithms, whereas ACI causes raw signal collision, uncoordinated interference, high bit error rates, and severe throughput collapse.
This confirms that introducing channels 3 and 8 creates destructive ACI rather than manageable CCI.

Key Concept

2.4 GHz Non-Overlapping Channel Planning and Adjacent-Channel Interference (ACI)
Estimated Time:2m 0s
Question 1687Question

During a network infrastructure review, a network engineer needs to analyze the flow of IP traffic, subnet boundaries, dynamic routing protocol relationships, and Virtual Router Redundancy Protocol (VRRP) virtual gateway IP assignments across enterprise core routers. The engineer does not need physical port placements, rack units, or cable path lengths. Which of the following diagrams or documentation types should the engineer consult?

Show answer & explanation

Answer: Logical network diagram

Answer

Logical network diagram
The correct option is the logical network diagram because it represents how data moves through the network, displaying subnets, IP addresses, VLAN IDs, routing protocols, and redundant virtual gateway configurations.

Step-by-Step Solution

1
Identify the required network details in the scenario.
The engineer needs details regarding IP traffic flow, subnet boundaries, dynamic routing protocols, and VRRP virtual IP assignments.
These elements describe Layer 2 and Layer 3 logical architectures.
2
Evaluate documentation types against the requirement.
Logical diagrams represent software-level and network-layer topologies, IP addressing structures, and protocols.
Physical, rack elevation, and wiring diagrams only detail hardware layouts, physical positions, and cable pinouts.

Key Concept

Logical vs. Physical Network Documentation
Question 1688Question

A network administrator configures a Layer 3 switch interface serving the Finance subnet (10.20.40.0/2410.20.40.0/24) with `ip helper-address 10.10.10.254` to direct DHCP traffic to a centralized DHCP server on the Management subnet (10.10.10.0/2410.10.10.0/24). When a client host on the Finance subnet broadcasts a DHCPDISCOVER packet, how does the Layer 3 switch process this packet before transmitting it to the DHCP server?

Show answer & explanation

Answer: It populates the gateway IP address (`giaddr`) field with the IP address of its receiving interface and forwards the packet as a unicast UDP message to destination port 67.

Answer

The Layer 3 switch populates the gateway IP address (`giaddr`) field with the receiving interface's IP address on the client subnet and forwards the packet as a unicast UDP message to the DHCP server at 10.10.10.254 on destination port 67.
When an `ip helper-address` (DHCP relay agent) is configured on a router or Layer 3 switch interface, it intercepts local DHCP broadcast messages (DHCPDISCOVER/DHCPREQUEST). The relay agent inserts the IP address of the interface that received the broadcast into the `giaddr` (gateway IP address) field of the DHCP message header. This informs the remote DHCP server which IP subnet scope to assign an address from. The relay agent then forwards the modified packet directly to the configured DHCP server IP as a unicast UDP packet on destination port 67.

Step-by-Step Solution

1
Intercept client broadcast
The Layer 3 switch receives a Layer 2/3 broadcast DHCPDISCOVER packet on the client-facing interface (10.20.40.110.20.40.1).
DHCP clients initially have no IP address, so they broadcast to find local DHCP servers.
2
Modify DHCP header (`giaddr`)
The switch inserts 10.20.40.110.20.40.1 into the gateway IP address (`giaddr`) field of the DHCP payload.
The centralized DHCP server uses the `giaddr` field to determine which subnet scope (10.20.40.0/2410.20.40.0/24) should be used for address allocation.
3
Unicast forward to destination server
The switch encapsulates the payload as a unicast UDP packet with source IP 10.20.40.110.20.40.1, destination IP 10.10.10.25410.10.10.254, and destination UDP port 67.
DHCP servers listen on UDP port 67 for both client broadcasts and relayed unicast messages.

Key Concept

DHCP Relay Agent Behavior and `giaddr` Header Insertion
Estimated Time:1m 0s
Question 1689Question

A edge gateway router receives candidate routes from multiple routing sources for the destination network 172.16.10.0/24172.16.10.0/24. The available entries are:

- An OSPF route with an Administrative Distance of 110110 and a metric cost of 4545
- An iBGP route with an Administrative Distance of 200200 and a metric of 1010
- A floating static route configured with an Administrative Distance of 130130

Which route will the gateway router install into its active routing table for traffic destined to 172.16.10.0/24172.16.10.0/24?

Show answer & explanation

Answer: The OSPF route, because its Administrative Distance of 110 is lower than both the floating static route and the iBGP route.

Answer

The OSPF route will be installed into the routing table because it has the lowest Administrative Distance (110) among the competing routes for the prefix 172.16.10.0/24.
When a router receives multiple routes for the exact same destination network prefix from different administrative sources, it evaluates Administrative Distance (AD) first. Lower AD values represent higher reliability. OSPF has an AD of 110, which is lower than the configured floating static route (130) and the iBGP route (200), so the router populates its routing table with the OSPF path.

Step-by-Step Solution

1
Evaluate the prefix lengths of all candidate routes.
All three candidate routes refer to the exact same prefix length (/24).
Longest prefix match does not filter out any route here since all prefixes are identical.
2
Compare the Administrative Distance (AD) values of the candidate routes.
OSPF AD = 110, Floating Static AD = 130, iBGP AD = 200.
When identical networks are learned from different sources, the route with the lowest Administrative Distance is preferred.
3
Select the route with the lowest Administrative Distance for insertion into the routing table.
The OSPF route (AD 110) is chosen.
110 is less than 130 and 200, so the OSPF route is installed into the active forwarding database.

Key Concept

Administrative Distance Precedence in Route Selection
Estimated Time:1m 15s
Question 1690Question

A network interface on a switch configured with IEEE 802.1D Spanning Tree Protocol (STP) experiences a link bring-up event. In what sequence does the port transition through its operational states from initial activation until it actively processes and forwards end-user network traffic? Place the STP port states in 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 IEEE 802.1D STP port states from initial link activation to full operation is: Blocking State, Listening State, Learning State, and Forwarding State.
In IEEE 802.1D STP, a switch port bringing up a link progresses strictly through Blocking → Listening → Learning → Forwarding. First, it starts in Blocking to listen for BPDUs without causing loops. Next, it moves to Listening to elect the Root Bridge and designate port roles. Then, it transitions to Learning to build MAC address tables without sending data. Finally, it enters Forwarding for normal data traffic.

Step-by-Step Solution

1
Identify the initial state upon link up
The port begins in the Blocking state to avoid network loops while waiting to receive BPDU traffic.
Default safety mechanism in 802.1D ensures ports do not forward data before knowing network topology.
2
Determine the STP election and topology evaluation phase
The port transitions from Blocking to the Listening state after the forward delay timer.
In Listening, the switch transmits and receives BPDUs to determine Root Bridge and port roles without learning MAC addresses or forwarding data.
3
Identify the MAC table population phase
The port transitions from Listening to the Learning state.
In Learning, the port populates its MAC address table from frame headers to prepare for frame forwarding, though user data forwarding remains disabled.
4
Identify the final fully operational phase
The port transitions from Learning to the Forwarding state.
The port now actively transmits and receives data frames, having safely passed all STP convergence convergence timers.

Key Concept

IEEE 802.1D Spanning Tree Protocol (STP) Port State Convergence Progression
Question 1691Question

Match each enterprise address translation requirement or scenario on the left with the correct NAT/PAT implementation method or routing behavior on the right.

Click a left item, then click its matching right item

Items

Providing an inbound persistent public IP mapping for an internal DMZ web server requiring fixed external access
Multiplexing thousands of internal client outbound sessions onto a single public IP address using unique transport layer ports
Assigning temporary, dynamic public IP addresses from a limited public subnet pool to active internal outbound hosts
Forwarding packets across internal subnets where host IP header addresses remain unchanged through transit

Matches

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Answer

Inbound persistent web server hosting corresponds to Static NAT (1:1 Translation). Outbound session multiplexing using unique transport ports corresponds to Port Address Translation (PAT / NAT Overload). Assigning temporary public IPs from a defined subnet pool corresponds to Dynamic NAT (Pool Translation). Packet forwarding without address alteration corresponds to Native IP Routing (No NAT).
Each requirement directly aligns with standard network implementation terminology: Static NAT provides a fixed 1:1 public-to-private IP mapping ideal for inbound public services; PAT (NAT Overload) allows many hosts to share a single public IP via port multiplexing; Dynamic NAT draws temporary 1:1 public addresses from a pool; and Native IP Routing forwards packets without translating IP header address fields.

Step-by-Step Solution

1
Analyze the requirement for hosting inbound services that require a consistent external identity.
Identify that persistent one-to-one mapping between inside local and inside global addresses is provided by Static NAT.
Static NAT provides a dedicated permanent public IP address so external clients can reach internal servers.
2
Analyze the requirement for sharing a single public IP address across multiple outbound client sessions.
Identify that mapping multiple internal IP addresses to one public IP via unique Layer 4 port tracking is performed by PAT (NAT Overload).
PAT tracks source ports at the transport layer to differentiate session traffic from distinct internal hosts sharing a common public IP.
3
Analyze the requirement for dynamic one-to-one temporary mapping from a public IP pool.
Identify that assigning available public addresses on demand from a configured range is performed by Dynamic NAT.
Dynamic NAT dynamically maps inside local addresses to available inside global addresses from a public address pool.
4
Analyze packet forwarding without modifying IP header addresses.
Identify that routing without address translation represents Native IP Routing.
Standard IP routing forwards packets based on routing table lookups without performing Network Address Translation.

Key Concept

NAT and PAT address mapping types and operational requirements
Question 1692Question

A network administrator is attempting to perform a manual zone transfer from an authoritative internal DNS server at 192.168.10.5192.168.10.5 for the domain internal.corp.cominternal.corp.com. While standard host resolution queries function normally, the zone transfer fails as shown in the command output below:

text
$ dig @192.168.10.5 internal.corp.com AXFR
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

Which of the following firewall configuration changes is required to resolve this DNS operational failure?

Show answer & explanation

Answer: Allow inbound traffic to destination TCP port 53 on the DNS server.

Answer

Allow inbound traffic to destination TCP port 53 on the DNS server.
DNS primary/secondary replication and manual zone transfers utilize the AXFR query type. Unlike standard lookup queries that run over UDP port 53, zone transfers require TCP port 53 to handle bulk data delivery securely and reliably without packet truncation. Opening TCP port 53 allows the client connection to establish successfully.

Step-by-Step Solution

1
Analyze the failed query command and output snippet.
The administrator attempted an Authoritative Transfer (AXFR) query against server 192.168.10.5192.168.10.5 using `dig`, resulting in a connection timeout.
Standard DNS resolution queries use UDP port 53, but AXFR operations require TCP port 53 due to data size and reliability requirements.
2
Evaluate transport layer requirements for DNS zone transfers.
Because standard DNS UDP queries succeeded while AXFR timed out, the intermediate firewall or host firewall is blocking TCP port 53 traffic while permitting UDP port 53.
AXFR transfers transmit the complete database of a DNS zone, which typically exceeds maximum UDP packet boundaries (512512 bytes without EDNS0) and requires TCP connection state.
3
Select the correct remediation policy.
Updating firewall rules to permit inbound traffic on TCP port 53 enables the client to establish a TCP handshake and complete the AXFR request.
Opening TCP port 53 fulfills the connection requirement without modifying valid query syntax or incorrectly altering transport protocols.

Key Concept

DNS Transport Protocols (UDP vs TCP Port 53)
Estimated Time:2m 0s
Question 1693Question

An enterprise network implements Rapid Spanning Tree Protocol (IEEE 802.1w) across its access switches. Switch-A is elected as the Root Bridge. Switch-B is connected directly to Switch-A using two parallel 1 Gbps Ethernet links: Link 1 connects Switch-A interface GigabitEthernet0/1 to Switch-B interface GigabitEthernet0/1, while Link 2 connects Switch-A interface GigabitEthernet0/2 to Switch-B interface GigabitEthernet0/2. All link speeds are identical, and all port priorities remain at default values (128128). Which port role and operational state will Switch-B assign to its GigabitEthernet0/2 interface?

Show answer & explanation

Answer: Alternate port in a discarding state

Answer

Alternate port in a discarding state
When a non-root switch receives Root Bridge BPDUs over multiple parallel links of identical cost from the same upstream switch, it breaks the tie by selecting the interface connected to the upstream port with the lowest numerical Port ID (Port Priority + Port Number). Switch-A's GigabitEthernet0/1 has a lower Port ID (128.1128.1) than GigabitEthernet0/2 (128.2128.2), so Switch-B selects its GigabitEthernet0/1 as the single Root Port. Under IEEE 802.1w (RSTP), the remaining redundant port receiving superior root BPDUs from another switch is assigned the Alternate port role and placed in a discarding state.

Step-by-Step Solution

1
Determine Root Bridge status and path cost for both links.
Switch-A is the Root Bridge. Both links are 1 Gbps with equal cumulative root path cost (44).
Since path costs are tied, the switch must proceed to subsequent tiebreakers.
2
Evaluate the upstream Neighbor Bridge ID tiebreaker.
Both links connect to the exact same upstream switch (Switch-A), resulting in identical upstream Bridge IDs.
When upstream Bridge IDs are tied, the switch evaluates the upstream Port Priority and Port ID.
3
Compare upstream Port IDs from Switch-A.
Switch-A transmits BPDUs with Port ID 128.1128.1 on GigabitEthernet0/1 and Port ID 128.2128.2 on GigabitEthernet0/2. 128.1<128.2128.1 < 128.2.
Lower numerical port ID is preferred. Switch-B selects its GigabitEthernet0/1 (connected to Switch-A Gi0/1) as the Root Port.
4
Determine the role and state for Switch-B's GigabitEthernet0/2 interface.
GigabitEthernet0/2 receives BPDUs from another switch interface providing an extra path to the Root Bridge. In 802.1w (RSTP), this interface becomes an Alternate port in a discarding state.
Alternate ports provide redundant paths toward the root bridge and remain in a discarding state to prevent switching loops.

Key Concept

RSTP Root Port Election & Alternate Port Role Assignment
Question 1694Question

A network administrator is designing a dynamic routing strategy for an enterprise infrastructure that uses both OSPF and EIGRP. Which of the following statements regarding routing metrics, administrative distance, and protocol operations are correct? (Select TWO)

Select all that apply

Show answer & explanation

Answer: OSPF calculates path cost based on link bandwidth, whereas EIGRP uses a composite metric derived primarily from bandwidth and delay by default.; If a router receives updates for the exact same destination network prefix from both internal EIGRP and OSPF, it will prefer the internal EIGRP route due to its lower administrative distance.

Answer

The correct statements are that OSPF calculates cost using link bandwidth while EIGRP uses a composite metric of bandwidth and delay, and that a router prefers internal EIGRP over OSPF for identical destination prefixes due to EIGRP's lower administrative distance.
OSPF determines path selection using a metric based on link bandwidth, while EIGRP uses a composite metric derived from bandwidth and delay by default. Additionally, when a router receives routes for the exact same network prefix from multiple dynamic protocols, it chooses the route with the lowest Administrative Distance (AD). Internal EIGRP (AD 90) is preferred over OSPF (AD 110).

Step-by-Step Solution

1
Evaluate metric calculation mechanisms for OSPF and EIGRP.
OSPF uses cost derived from interface bandwidth, whereas EIGRP uses a composite metric equation (defaulting to minimum bandwidth and cumulative delay).
Different dynamic routing protocols use distinct metrics to quantify path desirability.
2
Compare administrative distances for route selection between distinct dynamic protocols.
Internal EIGRP has a default Administrative Distance (AD) of 90, while OSPF has a default AD of 110.
When multiple routing sources offer paths to the exact same prefix, administrative distance determines which route is installed into the routing table, preferring lower values.
3
Distinguish Layer 3 routing operations from Layer 2 framing and address translation services.
OSPF operates at Layer 3 using LSAs, while PAT is a translation mechanism rather than a dynamic routing feature.
Ensures strict separation of networking concepts across OSI layers and administrative services.

Key Concept

Dynamic Routing Protocol Operations, Metrics, and Administrative Distance
Question 1695Question

Match each remote management technology with its primary administrative scenario or capability.

Click a left item, then click its matching right item

Items

Secure Shell (SSH)
Cellular Serial Console Server
IP-KVM Switch
Switched Power Distribution Unit (PDU)

Matches

Show answer & explanation

Answer

Secure Shell (SSH) matches encrypted CLI access over TCP port 22. Cellular Serial Console Server matches emergency out-of-band access during complete network link outages. IP-KVM Switch matches hardware-level BIOS/pre-boot control. Switched PDU matches remote power cycling of individual plugged-in devices.
Each management technology fulfills a specific operational requirement: Secure Shell (SSH) provides encrypted terminal administration across active network paths on TCP port 22; a Cellular Serial Console Server offers an out-of-band backchannel to physical console ports during primary link outages; an IP-KVM Switch delivers low-level graphical and keyboard/mouse control for server hardware prior to OS initialization; and a Switched PDU enables remote electrical power toggling of individual network appliance outlets.

Step-by-Step Solution

1
Differentiate between in-band and out-of-band (OOB) remote management transport mechanisms.
SSH relies on in-band operational production IP infrastructure, whereas serial console servers, IP-KVMs, and switched PDUs operate via out-of-band connectivity independent of the main data network.
Classifying the connection path establishes whether the tool requires production network interfaces to be operational.
2
Map each tool's functional capability to the administrative requirement.
SSH provides secure CLI access; cellular console servers restore direct RS-232 serial control during primary link loss; IP-KVM provides video and input control at the hardware pre-boot tier; switched PDUs allow power outlet control to force hard reboots.
Matching unique hardware capabilities to distinct troubleshooting scenarios ensures accurate selection.

Key Concept

Remote Access and Out-of-Band Management Tools
Question 1696Question

A network engineer is configuring a core router interface assigned the IPv4 address 10.16.42.138/2210.16.42.138/22. What is the broadcast address for this subnet?

Show answer & explanation

Answer: 10.16.43.255

Answer

The broadcast address for the 10.16.42.138/2210.16.42.138/22 subnet is 10.16.43.25510.16.43.255.
For the host IP 10.16.42.138/2210.16.42.138/22, the subnet mask is 255.255.252.0255.255.252.0. In the third octet, subnets increment by 4 (0,4,8,,40,440, 4, 8, \dots, 40, 44). The network address containing 10.16.42.13810.16.42.138 is 10.16.40.0/2210.16.40.0/22, and the subnet range spans from 10.16.40.010.16.40.0 to 10.16.43.25510.16.43.255. Therefore, the broadcast address for this subnet is 10.16.43.25510.16.43.255.

Step-by-Step Solution

1
Determine the subnet mask and block size from the CIDR prefix.
A /22/22 CIDR prefix corresponds to a subnet mask of 255.255.252.0255.255.252.0. The block size in the third octet is 256252=4256 - 252 = 4.
The CIDR prefix /22/22 allocates 22 bits to the network portion, leaving 2 network bits in the third octet.
2
Calculate the network boundary (Network ID) for the host IP address 10.16.42.13810.16.42.138.
The third octet network boundaries in increments of 4 are 0,4,8,,40,440, 4, 8, \dots, 40, 44. Since 42 lies between 40 and 44, the Network ID is 10.16.40.010.16.40.0.
The network ID is determined by rounding down to the nearest multiple of the block size in the third octet.
3
Calculate the broadcast address of the subnet.
The next network boundary is 10.16.44.010.16.44.0. Subtracting 1 from this address gives the broadcast address 10.16.43.25510.16.43.255.
The broadcast address is the highest possible IP address within the subnet range, setting all 10 host bits to 1.

Key Concept

IPv4 Subnetting and Broadcast Address Calculation
Question 1697Question

A network administrator is planning a wireless deployment in a facility using the 2.4 GHz frequency band in North America. To avoid adjacent-channel interference between neighboring access points, which of the following standard 2.4 GHz channels should be selected for cell assignment? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Channel 1; Channel 6

Answer

Channel 1 and Channel 6 are standard non-overlapping 2.4 GHz channels.
In the 2.4 GHz Wi-Fi band (802.11b/g/n), each 20 MHz channel requires a 25 MHz separation between center frequencies to be completely non-overlapping. In North America, the three designated non-overlapping channels are 1, 6, and 11. Therefore, selecting Channel 1 and Channel 6 provides non-overlapping wireless coverage.

Step-by-Step Solution

1
Identify the frequency band and regional standard
The scenario specifies the 2.4 GHz Wi-Fi spectrum under North American channel allocation rules.
Standard 2.4 GHz channels operate on frequencies spaced 5 MHz apart, requiring a separation of 20 MHz or 25 MHz between center frequencies to prevent overlapping.
2
Determine the non-overlapping channel set
Channels 1, 6, and 11 do not overlap with each other in the 2.4 GHz spectrum.
Choosing non-overlapping channels prevents co-channel and adjacent-channel interference between neighboring access points.
3
Evaluate the provided choices
Channel 1 and Channel 6 are non-overlapping options, while Channels 2, 3, and 4 overlap with Channels 1 and 6.
Selecting Channel 1 and Channel 6 ensures clean wireless cell boundaries.

Key Concept

Non-Overlapping 2.4 GHz Wi-Fi Channels
Question 1698Question

An organization is updating its enterprise documentation repository to separate physical infrastructure details from logical network topology maps. Which of the following components should be documented exclusively within the physical network documentation? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Cable tag identifiers and patch panel port assignments for structured wiring; Vertical unit (U) positions and chassis layout within equipment enclosures

Answer

Physical network documentation must include physical cable labeling identifiers/patch panel port assignments and vertical unit placement within racks.
Physical network documentation records tangible assets and spatial layouts. Port assignments on patch panels, structured cable labels, and vertical rack unit (U) positions within equipment racks are physical characteristics required for cable tracing, installation, and hardware inventory management.

Step-by-Step Solution

1
Differentiate physical network documentation from logical network documentation.
Physical documentation focuses on tangible infrastructure (cables, ports, rack locations, hardware dimensions), whereas logical documentation focuses on software data paths (IP addresses, VLANs, routing protocols, STP priorities).
Clear segregation of documentation types ensures efficient physical maintenance and accurate logical troubleshooting.
2
Identify physical elements among the choices.
Cable tag identifiers, patch panel port assignments, and vertical rack unit (U) placement describe tangible physical assets.
These elements are necessary for technicians tracing physical copper/fiber runs or mounting hardware inside telecommunication racks.
3
Filter out logical protocol and addressing details.
BGP ASNs, IP subnets/VLAN IDs, and STP priorities belong strictly to logical network topology diagrams.
Logical attributes remain independent of physical cabinet or cabling layouts.

Key Concept

Physical Network Documentation vs. Logical Topology Documentation
Question 1699Question

A network technician is setting up an automated boot-server infrastructure to distribute basic initialization configuration files to newly unboxed network switches across different subnets. The process relies on Trivial File Transfer Protocol (TFTP) for lightweight, connectionless file transfer. Which transport layer protocol and destination port number must be allowed through the intermediate firewalls to permit this traffic?

Show answer & explanation

Answer: UDP port 69

Answer

UDP port 69 is required for Trivial File Transfer Protocol (TFTP) communication.
The correct answer specifies UDP port 69. Trivial File Transfer Protocol (TFTP) is a simplified file transfer protocol that operates over UDP on standard destination port 69, making it ideal for low-overhead bootstrap file distribution to network devices.

Step-by-Step Solution

1
Identify the protocol requirements specified in the scenario.
The scenario requires configuring firewall rules for Trivial File Transfer Protocol (TFTP).
TFTP is a lightweight file transfer protocol frequently used for bootstrap file loading and network hardware firmware provisioning.
2
Determine the transport protocol and default port used by TFTP.
TFTP operates at the application layer and uses UDP at the transport layer on destination port 69.
Unlike standard FTP which uses TCP ports 20 and 21 for reliable connection-oriented transfer, TFTP is designed for simple, minimal overhead operations using connectionless UDP.

Key Concept

Trivial File Transfer Protocol (TFTP) Port and Transport Protocol
Question 1700Question

A network administrator is organizing security auditing profiles and intermediate firewall access rules for essential enterprise infrastructure services. Match each network protocol on the left with its corresponding default port and transport layer protocol on the right.

Click a left item, then click its matching right item

Items

NTP (Network Time Protocol)
IMAPS (Internet Message Access Protocol Secure)
Telnet
SMTPS (Simple Mail Transfer Protocol Secure)

Matches

Show answer & explanation

Answer

NTP matches with UDP 123; IMAPS matches with TCP 993; Telnet matches with TCP 23; SMTPS matches with TCP 465.
Each network service is matched directly to its official transport protocol and default listening port: NTP uses UDP 123, IMAPS uses TCP 993, Telnet uses TCP 23, and SMTPS uses TCP 465.

Step-by-Step Solution

1
Identify the transport protocol and default port for time synchronization services (NTP).
NTP operates over UDP port 123.
Time synchronization relies on low-latency, connectionless transmission over UDP 123.
2
Identify the transport protocol and default port for secure mailbox access (IMAPS).
IMAPS operates over TCP port 993.
Standard unencrypted IMAP uses TCP 143, whereas secure IMAPS wraps the session in TLS on TCP 993.
3
Identify the transport protocol and default port for unencrypted legacy command-line management (Telnet).
Telnet operates over TCP port 23.
Telnet establishes cleartext command-line communication using TCP port 23.
4
Identify the transport protocol and default port for secure mail submission (SMTPS).
SMTPS operates over TCP port 465.
Standard SMTP uses TCP 25, while implicit TLS-encrypted SMTPS uses TCP port 465.

Key Concept

Common Network Ports and Protocols
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