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Tüm türler2,237Çoktan seçmeli1,150Çoklu seçim488Sayısal30Eşleştirme350Sıralama201Kısa cevap18
Soru 1901Soru →

A network administrator is troubleshooting a reverse DNS resolution failure for an internal database server with IP address 192.168.10.45192.168.10.45. The administrator executes a diagnostic command on a client workstation and receives the following output:

text
$ dig -x 192.168.10.45

;; QUESTION SECTION:
;45.10.168.192.in-addr.arpa. IN PTR

;; ANSWER SECTION:

;; AUTHORITY SECTION:
10.168.192.in-addr.arpa. 3600 IN SOA ns1.corp.internal. admin.corp.internal. 2026072701 7200 3600 1209600 3600

;; SERVER: 192.168.10.2#53(192.168.10.2)

Based on the diagnostic output, which of the following DNS configuration changes is required on the authoritative server to resolve the query successfully?

Cevabı ve açıklamayı göster

Cevap: Add a PTR record mapping 45.10.168.192.in−addr.arpa.45.10.168.192.in-addr.arpa. to the database server's fully qualified domain name (FQDN).

Cevap

Add a PTR record mapping 45.10.168.192.in−addr.arpa.45.10.168.192.in-addr.arpa. to the database server's fully qualified domain name (FQDN).
The `dig -x` diagnostic tool requests a reverse DNS lookup for an IP address. The command output shows a query for `45.10.168.192.in−addr.arpa.45.10.168.192.in-addr.arpa.`. Because the server returns an AUTHORITY section with an SOA record but no ANSWER section, the reverse lookup zone is present on the server, but the specific PTR record for host address 192.168.10.45192.168.10.45 has not been configured.

Adım Adım Çözüm

1
Analyze the command and query type
The `dig -x 192.168.10.45` command initiates a reverse DNS lookup, requesting a Pointer (PTR) record for the domain `45.10.168.192.in−addr.arpa.45.10.168.192.in-addr.arpa.`.
Reverse DNS resolution queries the `.in-addr.arpa` domain hierarchy using octets reversed.
2
Inspect the query output sections
The ANSWER section is empty, while the AUTHORITY section provides the SOA record for the zone `10.168.192.in-addr.arpa.`.
An empty ANSWER section with an authoritative SOA response indicates the server is authoritative for the zone, but no resource record matching `45.10.168.192.in−addr.arpa.45.10.168.192.in-addr.arpa.` exists.
3
Identify the required record creation
Create a PTR record for host 4545 within the 10.168.192.in−addr.arpa.10.168.192.in-addr.arpa. reverse zone pointing to the canonical FQDN.
PTR records perform IP address-to-hostname resolution.

Anahtar Kavram

Reverse DNS Resolution and PTR Records
Soru 1902Soru →

A network administrator is troubleshooting an issue where a workstation attached to Switch-A on port FastEthernet 0/5 experiences severe latency and dropped frames during file transfers to a server in the same VLAN on Switch-B. Switch-A logs indicate frequent speed and duplex mismatch alerts, and interface counters show a high count of late collisions on FastEthernet 0/5. Physical cable testing verifies the cabling is intact. The workstation's network interface is manually configured for 100 Mbps Full Duplex, whereas the switch port is set to auto-negotiation. Which of the following is the root cause of the performance degradation and frame loss on this link?

Cevabı ve açıklamayı göster

Cevap: Auto-negotiation on the switch interface defaulted to Half Duplex after failing duplex detection, resulting in a duplex mismatch with the host.

Cevap

Auto-negotiation on the switch interface defaulted to Half Duplex after failing duplex detection, resulting in a duplex mismatch with the host.
When an end device interface is hardcoded to Full Duplex while the switch port auto-negotiates, auto-negotiation cannot establish duplex settings. The switch interface detects the 100 Mbps signal through parallel detection but defaults to Half Duplex in accordance with IEEE standards. The resulting duplex mismatch causes the full-duplex workstation to send frames regardless of line state, leading the half-duplex switch port to register late collisions, buffer congestion, and heavy packet loss.

Adım Adım Çözüm

1
Analyze the link negotiation settings configured on both endpoints.
Identified that the workstation host is hardcoded to 100 Mbps Full Duplex while the connected switch port relies on auto-negotiation.
Mismatched link negotiation methods prevent duplex parameter exchange signals from completing.
2
Determine the IEEE auto-negotiation fallback behavior for duplex selection.
The switch port detects the 100 Mbps signal via parallel detection but cannot negotiate duplex mode, defaulting to Half Duplex per standard IEEE rules.
Standard Ethernet auto-negotiation specifies falling back to Half Duplex when duplex detection fails.
3
Correlate the duplex mismatch condition with interface error counters.
The full-duplex host transmits without line sensing while the half-duplex switch port senses collisions mid-frame, recording late collisions and packet drops.
High rates of late collisions during active file transfers are a definitive diagnostic indicator of a duplex mismatch.

Anahtar Kavram

Duplex Mismatch and Auto-Negotiation Fallback
Soru 1903Soru →

A network administrator is deploying a wireless network across a multi-story office building. Due to high access point density, multiple access points on different floors must share the same 5 GHz5\text{ GHz} channel, resulting in co-channel interference (CCI) and contention delays. Which feature introduced in the IEEE 802.11ax standard enables access points to identify overlapping basic service sets and transmit simultaneously over shared channels when preamble energy levels are below a color-aware threshold?

Cevabı ve açıklamayı göster

Cevap: BSS Coloring

Cevap

BSS Coloring is the Wi-Fi 6 (802.11ax) spatial reuse mechanism designed to differentiate traffic from overlapping basic service sets on the same channel.
The correct option is BSS Coloring. In IEEE 802.11ax (Wi-Fi 6), BSS Coloring adds a 6-bit identifier (color code) to the preamble of wireless frames. This mechanism enables wireless devices to distinguish between frame transmissions from their own network and neighboring overlapping networks on the same channel. When a frame from an overlapping network is detected with a different 'color', the receiver can adjust its adaptive signal detection threshold, enabling simultaneous transmissions (spatial reuse) and significantly mitigating co-channel interference.

Adım Adım Çözüm

1
Identify the primary network performance issue
Co-channel interference (CCI) caused by overlapping access points operating on identical frequency channels.
When access points share a channel, legacy Wi-Fi contention (CSMA/CA) forces devices to defer transmission whenever any preamble on that channel is detected above the clear channel assessment (CCA) threshold.
2
Analyze the features introduced in IEEE 802.11ax for spatial reuse
802.11ax introduces BSS Coloring, which attaches a 6-bit color field to the PHY header of frames.
This allows a client or AP to distinguish between its own basic service set (my BSS) and a neighboring BSS (overlapping BSS). If the frame is from an overlapping BSS and below a secondary energy threshold, the device can transmit concurrently.

Anahtar Kavram

BSS Coloring and Spatial Reuse in IEEE 802.11ax
Soru 1904Soru →

A network administrator is preparing updated documentation following the deployment of a new Layer 3 collapsed core network structure. The documentation must specifically detail IP address assignments, VLAN identifiers, subnet boundaries, and active routing protocol relationships across all virtual interfaces, while excluding physical cable routes and equipment rack positions. Which type of documentation is best suited for this requirement?

Cevabı ve açıklamayı göster

Cevap: Logical topology diagram

Cevap

The logical topology diagram is the correct choice because it documents IP subnets, VLAN arrangements, and logical routing pathways independently of physical hardware locations.
The logical topology diagram is designed specifically to visualize how data flows through a network. It details IP addresses, subnet masks, VLAN names/numbers, virtual router interfaces, and dynamic routing protocols without cluttering the view with physical cable paths or hardware rack locations.

Adım Adım Çözüm

1
Analyze the documentation requirements stated in the scenario
Identified the need to document IP addressing, VLAN IDs, subnet boundaries, and routing protocol interactions.
Determining whether the data represents physical placement or logical protocol flow dictates the proper diagram type.
2
Evaluate the difference between logical and physical network artifacts
Physical diagrams focus on cabling and hardware locations, whereas logical diagrams map software layer configurations and traffic paths.
Excluding cable runs and rack placement points directly away from physical topologies, wiring schematics, and rack diagrams.
3
Select the matching network documentation type
The logical topology diagram perfectly satisfies the requirement to illustrate network subnets, VLANs, and Layer 3 routing topology.
Logical diagrams represent the virtual organization of the network.

Anahtar Kavram

Logical vs. Physical Network Topology Documentation
Tahmini Süre:1m 0s
Soru 1905Soru →

An enterprise systems engineer is resolving name lookup and mail transport issues for the internal domain `hr.enterprise.internal`. The engineer executes the following diagnostic command to inspect the domain's resource records:

$ dig +noall +answer hr.enterprise.internal MX
hr.enterprise.internal. 3600 IN MX 10 smtp1.enterprise.internal.

A subsequent lookup query directed to `smtp1.enterprise.internal` returns no address records, preventing mail transfer agents from connecting to the server.

Based on standard DNS infrastructure requirements and protocol operations, which TWO of the following configurations or administrative actions are required to restore proper functionality?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Add an A or AAAA record for host `smtp1.enterprise.internal` mapping the hostname to the mail server's IP address.; Ensure that network firewall rules permit client and server traffic on UDP port 53 for standard DNS name resolution queries.

Cevap

The resolution requires adding an A or AAAA record mapping `smtp1.enterprise.internal` to its IP address, and ensuring firewalls permit UDP port 53 traffic for standard DNS name queries.
Mail Exchanger (MX) records point to host domain names rather than IP addresses directly. Consequently, an A record (for IPv4) or an AAAA record (for IPv6) must exist for the specified target hostname so that clients can resolve the mail server's IP address. Additionally, DNS name resolution relies on UDP port 53 for standard client query and response traffic.

Adım Adım Çözüm

1
Analyze the MX record output from the diagnostic lookup.
The MX record points to the hostname `smtp1.enterprise.internal` as the designated mail server.
An MX record only specifies the domain name of the mail gateway, requiring an underlying address record to determine the target IP.
2
Identify the missing host address record required to complete host resolution.
An A record (IPv4) or AAAA record (IPv6) must be configured for `smtp1.enterprise.internal`.
Without an A/AAAA record, mail transfer agents cannot translate the host domain name returned by the MX query into a network layer IP address.
3
Identify the proper protocol and port configuration for DNS service traffic.
Ensure UDP port 53 is open and accessible.
Standard iterative and recursive DNS queries rely on UDP port 53 for lightweight, low-overhead communication.

Anahtar Kavram

DNS MX Record Host Resolution Dependency and Core DNS Port/Protocol Operation
Soru 1906Soru →

A network technician is preparing antenna hardware for various deployment zones across a new corporate campus facility. Match each antenna type on the left with its corresponding radiation pattern and primary deployment scenario on the right.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Omnidirectional Antenna
Patch Antenna
Parabolic Dish Antenna
Yagi Antenna

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Omnidirectional Antenna pairs with 360-degree central ceiling coverage; Patch Antenna pairs with semi-directional wall coverage for hallways; Parabolic Dish Antenna pairs with narrow high-gain beam for long-distance point-to-point outdoor links; Yagi Antenna pairs with directional moderate-gain coverage for point-to-multipoint links.
Each antenna type is uniquely matched to its radiation geometry: omnidirectional antennas broadcast 360 degrees indoors; patch antennas provide semi-directional coverage along flat walls/hallways; parabolic dish antennas generate focused high-gain beams for long-range point-to-point bridges; and Yagi antennas provide directional moderate-gain coverage for outdoor links.

Adım Adım Çözüm

1
Analyze the radiation pattern requirement for general indoor open office spaces.
Central indoor coverage requires equal signal distribution in all horizontal directions (360 degrees), matching the omnidirectional antenna pattern.
Ceiling-mounted access points in the middle of a floor plan rely on omnidirectional radiation to reach clients surrounding the access point.
2
Analyze corridor and wall-mounted indoor directional needs.
A wall-mounted deployment directing signal along a hallway requires semi-directional coverage, matching the patch antenna.
Patch antennas prevent RF energy from radiating into wall spaces behind the antenna and focus energy forward.
3
Differentiate between outdoor directional antennas based on distance and beamwidth focal properties.
Extremely narrow beamwidth over long distances requires a high-gain parabolic dish, while moderate directional links utilize a Yagi antenna.
Parabolic reflector dishes maximize gain and minimize beam dispersion across multi-kilometer point-to-point links.

Anahtar Kavram

Wireless Antenna Types, Radiation Patterns, and Deployment Scenarios
Soru 1907Soru →

A network engineer is auditing documentation prior to integrating a hybrid cloud extension into an existing enterprise environment. Which of the following components should be documented specifically within a logical network topology diagram rather than a physical network topology diagram? (Select TWO).

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: IP subnet allocations and network prefix boundaries; VLAN IDs and assigned layer 3 gateway interfaces

Cevap

IP subnet allocations with network prefix boundaries and VLAN IDs with assigned layer 3 gateway interfaces should be documented within a logical network topology diagram.
Logical network topology diagrams illustrate data path relationships, network layer addressing, and logical broadcast domains regardless of physical physical equipment placement. Therefore, IP subnet allocations with CIDR notation and VLAN designations with their corresponding Layer 3 gateways are core logical diagram elements.

Adım Adım Çözüm

1
Differentiate between logical and physical topology documentation requirements.
Logical topology diagrams depict how data flows through a network, focusing on IP addressing, VLANs, subnets, and routing protocols, independent of physical location.
Understanding the separation of logical and physical documentation ensures accurate network auditing and troubleshooting.
2
Evaluate each candidate item against the logical topology definition.
IP subnets and VLAN IDs represent logical constructs. Rack unit locations, cable media categories, and physical MAC addresses represent physical hardware and cabling specifications.
Items bound to physical hardware layout belong in physical diagrams or rack elevation schematics.

Anahtar Kavram

Logical vs. Physical Network Topology Documentation
Tahmini Süre:1m 30s
Soru 1908Soru →

A network administrator is investigating an issue where a client workstation (10.20.40.1510.20.40.15) fails to connect to an internal web service running on port 80808080 at 10.20.40.25010.20.40.250. The administrator executes two command-line diagnostic utilities from the workstation, producing the following terminal outputs:

Command 1: `ping 10.20.40.250`

Pinging 10.20.40.250 with 32 bytes of data:
Reply from 10.20.40.250: bytes=32 time=2ms TTL=64
Reply from 10.20.40.250: bytes=32 time=1ms TTL=64

Command 2: `tracert -d 10.20.40.250`

Tracing route to 10.20.40.250 over a maximum of 30 hops
1 <1 ms <1 ms <1 ms 10.20.40.250
Trace complete.

Based on these diagnostic results, which TWO of the following conclusions are valid? (Select TWO.)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The destination host resides on the same local network segment as the client workstation.; Basic Layer 3 IP reachability to the destination host is confirmed via ICMP.

Cevap

The destination host resides on the same local network segment as the client workstation, and basic Layer 3 IP reachability to the destination host is confirmed via ICMP.
A single hop in the traceroute output confirms that the client workstation and target server share the same local network segment without crossing a router. Furthermore, receiving ICMP echo replies from ping validates basic Layer 3 IP reachability.

Adım Adım Çözüm

1
Analyze the ping command output.
Received successful ICMP Echo replies from 10.20.40.250 with low round-trip times.
Confirms operational Layer 3 IP reachability between the client and server.
2
Analyze the tracert -d command output.
The target IP address is reached in a single hop.
Indicates no intermediate routers were traversed, proving both hosts reside on the same broadcast domain and IP subnet.
3
Evaluate the limitation of ping regarding TCP port testing.
Recognize that ICMP reachability does not guarantee that TCP port 8080 is open or listening.
ICMP functions at the Network layer (Layer 3), whereas TCP port 8080 operates at the Transport layer (Layer 4).

Anahtar Kavram

Utilizing Command-Line Network Troubleshooting Utilities
Soru 1909Soru →

A network administrator is allocating IP addresses for a high-availability firewall cluster. The segment is assigned a subnet mask of 255.255.255.248255.255.255.248. How many usable host IP addresses are available for assignment in this subnetwork?

Cevabı ve açıklamayı göster

Cevap: 6

Cevap

There are 6 usable host IP addresses available in a subnetwork assigned a 255.255.255.248255.255.255.248 subnet mask.
A subnet mask of 255.255.255.248255.255.255.248 corresponds to a /29/29 CIDR prefix length. This leaves 3 host bits (32−29=332 - 29 = 3), providing 23=82^3 = 8 total IP addresses per subnet block. Subtracting 2 for the network ID (all host bits 0) and the directed broadcast address (all host bits 1) leaves exactly 6 usable host IP addresses.

Adım Adım Çözüm

1
Calculate the total block size of IP addresses in the subnet
256−248=8256 - 248 = 8 total IP addresses
The subnet mask octet of 248 indicates a block size of 8 total addresses (23=82^3 = 8 host bits).
2
Subtract reserved network and broadcast addresses
8−2=68 - 2 = 6 usable host IP addresses
The network ID (first address) and broadcast address (last address) cannot be assigned to hosts.

Anahtar Kavram

Calculating Usable Host IP Addresses from Subnet Masks
Tahmini Süre:1m 0s
Soru 1910Soru →

A network technician is troubleshooting a newly installed Category 6 UTP cable drop connecting a desktop computer to a wall outlet. The workstation successfully connects at 100 Mbps Fast Ethernet, but fails to establish a 1000BASE-T (Gigabit Ethernet) link. A basic wiremap continuity tester indicates that all eight conductor pins match correctly end-to-end (pins 1 through 8 are straight-through). Which of the following diagnostic findings or testing methods would most likely identify the root cause of this failure? (Select TWO)

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: A split pair condition is present on the termination points, allowing DC continuity to pass while causing severe high-frequency crosstalk.; Using a cable certifier to measure Near-End Crosstalk (NEXT) and attenuation parameters across all four pairs.

Cevap

The physical failure is identified by recognizing a split pair condition at the termination points and utilizing a cable certifier to measure Near-End Crosstalk (NEXT) and attenuation.
Gigabit Ethernet (1000BASE-T) relies on all four pairs working with tight differential noise rejection. A split pair retains pin-to-pin continuity (passing simple wiremap devices) but breaks pair pairing, generating excessive Near-End Crosstalk (NEXT). A cable certifier evaluates NEXT, attenuation, and frequency compliance to accurately diagnose this condition.

Adım Adım Çözüm

1
Analyze the reported symptoms and test results.
100BASE-TX operates on two pairs (pins 1, 2, 3, and 6), whereas 1000BASE-T requires all four pairs (pins 1-8). Basic continuity testers verify DC pin-to-pin connectivity but cannot test high-frequency signal integrity or pair pairing consistency.
Passing a basic continuity test proves electrical connection, but does not guarantee that wires are paired according to T568A/T568B color standards.
2
Identify the physical impairment cause.
Split pairs maintain 1-to-1 pin connections across both ends (passing basic continuity checks), but separate the twisted pairs. This leads to severe crosstalk at high frequencies, preventing 1 Gbps speed negotiation.
Ethernet twisted pairs rely on balanced differential signaling to reject cross-talk; untwisting or splitting pairs disrupts differential cancellation.
3
Select the appropriate diagnostic tool for confirmation.
A advanced cable certifier tests RF performance indicators such as NEXT, FEXT, return loss, and attenuation.
Advanced parameter measurement is required to pinpoint physical layer faults that simple continuity or tone testing tools miss.

Anahtar Kavram

Identifying Split Pairs and Cable Certification Testing
Soru 1911Soru →

Match each network troubleshooting scenario to the most appropriate hardware diagnostic tool or packet analyzer feature.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Locating the precise distance to a high-attenuation splice loss or macrobend on a single-mode fiber-optic run
Analyzing frame-level Ethernet header fields to isolate unauthorized DHCP OFFER broadcasts on a subnet
Identifying pinout transposition errors, such as reversed pairs or split pairs, on a newly crimped Cat 6 RJ-45 cable
Validating the physical transmit and receive circuitry of an isolated Ethernet interface port without a switch connection

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

The diagnostic scenarios map to their respective tools based on physical medium and OSI layer: OTDR measures light reflection to pinpoint distance to fiber anomalies, Packet Analyzer decodes frame payloads for protocol inspection, Wiremap Tester evaluates individual pinout continuity on copper cables, and Loopback Plug isolates local port hardware transceiver operation.
Each diagnostic scenario requires matching the target media and Layer of the OSI model: an OTDR uses backscattered light to locate distance to fiber macrobends; a packet analyzer decodes protocol headers to detect rogue DHCP OFFER traffic; a wiremap tester verifies pin-to-pin conductor integrity on UTP terminations; and a loopback plug isolates local NIC hardware by looping transmit signals to receive pins.

Adım Adım Çözüm

1
Evaluate the optical fiber fault distance measurement requirement.
Select the Optical Time-Domain Reflectometer (OTDR).
OTDR measures backscattered light over time to calculate exact distances to optical attenuation points, splices, or breaks.
2
Examine the protocol inspection and frame decoding requirement.
Select the Packet Analyzer.
Protocol analysis software captures upper-layer traffic to inspect header flags, DHCP options, and ARP broadcast payloads.
3
Assess the copper cabling conductor pinout check scenario.
Select the Wiremap Tester.
Wiremap testing checks pin-to-pin conductor continuity across RJ-45 terminations to detect wiring layout faults.
4
Determine how to test physical port transceivers without an active network link.
Select the Loopback Plug.
A loopback plug redirects outgoing transmit signals into the local receiver pins to verify host NIC hardware functionality.

Anahtar Kavram

Hardware Diagnostic Tools and Packet Analyzer Selection
Soru 1912Soru →

A network engineer is investigating excessive link degradation and packet loss on a 10GBASE-LR single-mode fiber link connecting two campus buildings spaced 1.2 kilometers apart. An optical power meter confirms that received optical power is 16 dB below expected baseline levels, indicating high attenuation along the path. Which diagnostic tool should the engineer use to identify the precise distance to the macrobend or splice fault causing the signal loss?

Cevabı ve açıklamayı göster

Cevap: Optical Time-Domain Reflectometer (OTDR)

Cevap

An Optical Time-Domain Reflectometer (OTDR) should be used because it measures light reflections along an optical fiber cable to locate the precise distance to physical faults, splices, and severe attenuation points.
The Optical Time-Domain Reflectometer (OTDR) is specifically designed for optical fiber media. It injects light pulses down the fiber core and measures the time and intensity of light reflected back (Rayleigh backscattering and Fresnel reflections). This allows the tool to display a trace mapping the precise distance to splices, connectors, macrobends, or physical breaks.

Adım Adım Çözüm

1
Analyze the physical medium and problem type
The scenario specifies single-mode optical fiber media exhibiting high attenuation (excessive dB loss).
Selecting the correct tester requires identifying whether the medium is copper or fiber.
2
Determine the diagnostic requirement
The technician needs to locate the exact position (distance) of a physical Layer 1 optical fault.
While an optical power meter measures total loss, pinpointing distance to a break or bend requires reflection analysis.
3
Select the appropriate hardware tester
An Optical Time-Domain Reflectometer (OTDR) transmits light pulses into the fiber and calculates fault distances based on return time and light scattering.
OTDR is the industry-standard tool for graphical signature and distance measurement of fiber optic link anomalies.

Anahtar Kavram

Fiber Optic Physical Layer Troubleshooting with OTDR
Soru 1913Soru →

A network engineer is configuring static host IP addresses for infrastructure devices within the newly assigned network block 10.88.16.0/2010.88.16.0/20. Which of the following IPv4 addresses represents the last valid, usable host address in this subnet?

Cevabı ve açıklamayı göster

Cevap: 10.88.31.25410.88.31.254

Cevap

10.88.31.25410.88.31.254
For the subnet 10.88.16.0/2010.88.16.0/20, the subnet mask is 255.255.240.0255.255.240.0, giving a block size of 16 in the third octet. The network span is from 10.88.16.010.88.16.0 to 10.88.31.25510.88.31.255. Reserving 10.88.16.010.88.16.0 for the network ID and 10.88.31.25510.88.31.255 for the broadcast address leaves 10.88.16.110.88.16.1 through 10.88.31.25410.88.31.254 as usable host addresses. Therefore, 10.88.31.25410.88.31.254 is the last valid usable host IP.

Adım Adım Çözüm

1
Calculate the subnet mask and third-octet block size for a /20 prefix.
A /20 prefix corresponds to the mask 255.255.240.0255.255.240.0. The block size in the third octet is 256−240=16256 - 240 = 16.
The third octet contains 4 network bits and 4 host bits (24=162^4 = 16).
2
Determine the network boundary and broadcast address.
Starting at network ID 10.88.16.010.88.16.0, adding 16 to the third octet gives the next subnet starting at 10.88.32.010.88.32.0. Thus, the broadcast address is 10.88.31.25510.88.31.255.
The broadcast address is one address before the start of the next subnet.
3
Identify the last usable host IP address.
Subtracting 1 from the broadcast address (10.88.31.255−110.88.31.255 - 1) yields 10.88.31.25410.88.31.254.
The last usable host address is always the IP immediately preceding the subnet broadcast address.

Anahtar Kavram

IPv4 Subnet Host Boundaries and Allocation
Tahmini Süre:1m 15s
Soru 1914Soru →

A network technician is troubleshooting an IP surveillance camera connected via an 80-meter Category 6 Ethernet drop. Although basic wiremap testing confirms all eight conductors have pin-to-pin continuity with no opens or shorts, the camera regularly experiences frame drops and fails to negotiate a 1000Base-T link, falling back to 100Mbps. The technician suspects high signal degradation and Near-End Crosstalk (NEXT) caused by excessive untwisting of wire pairs near the patch panel punch-down termination. Which of the following tools should the technician use to perform a full frequency performance analysis and verify whether the cable run complies with Category 6 standards?

Cevabı ve açıklamayı göster

Cevap: Cable certifier

Cevap

The cable certifier is the appropriate tool because it measures complex signal performance metrics such as Near-End Crosstalk (NEXT) and attenuation across category standards.
The option recommending a cable certifier is correct because certifiers perform full-spectrum electrical testing across the frequency range required by TIA/EIA standards (such as Cat 6), measuring parameters like Near-End Crosstalk (NEXT), return loss, and attenuation to verify 1000Base-T capability.

Adım Adım Çözüm

1
Analyze the reported symptoms and physical environment.
Basic DC continuity and pin mapping pass, eliminating opens, shorts, and wiremap errors as the cause of failure. However, Gigabit link negotiation fails and high-speed traffic drops frames over an 80-meter Category 6 run.
When pin continuity is intact but high-speed link negotiation fails, high-frequency transmission parameters like crosstalk or attenuation are failing.
2
Identify the specific performance parameter being tested.
The technician suspects Near-End Crosstalk (NEXT) due to un-twisted copper conductors near the patch panel.
NEXT occurs when signals on one wire pair bleed into an adjacent pair due to degraded pair twisting or poor termination practice.
3
Select the diagnostic instrument capable of assessing high-frequency cable standards.
Choose a cable certifier.
Only a cable certifier tests electrical performance against TIA/EIA standard specifications (e.g., Cat 6 up to 250 MHz) to qualify cabling for specific Ethernet standards like 1000Base-T.

Anahtar Kavram

Selecting Cabling Troubleshooting Tools for High-Frequency Certification
Tahmini Süre:1m 15s
Soru 1915Soru →

A network technician configures an 802.1Q trunk link between Switch-1 and Switch-2. Switch-1 is configured with native VLAN 10, whereas Switch-2 is configured with native VLAN 20. Users connected to VLAN 10 on Switch-1 report that they can unexpectedly reach servers on VLAN 20 attached to Switch-2 without going through a router, while console logs generate periodic CDP error messages. Which of the following best explains the root cause of this cross-VLAN communication?

Cevabı ve açıklamayı göster

Cevap: Untagged frames sent from VLAN 10 on Switch-1 travel across the trunk link and are automatically placed into native VLAN 20 upon arrival at Switch-2.

Cevap

Untagged frames sent from VLAN 10 on Switch-1 travel across the trunk link and are automatically placed into native VLAN 20 upon arrival at Switch-2.
Under 802.1Q encapsulation, frames originating from the native VLAN are sent across a trunk link untagged. When neighboring switches have mismatched native VLAN settings (VLAN 10 on one end and VLAN 20 on the other), untagged frames originating on VLAN 10 are ingested by the receiving switch and mapped directly into VLAN 20. This creates a security leak and unexpected Layer 2 connectivity between two distinct VLANs.

Adım Adım Çözüm

1
Analyze the 802.1Q trunking behavior regarding native VLANs.
802.1Q trunking transmits frames belonging to the native VLAN without inserting an 802.1Q VLAN tag.
Native VLAN traffic is intentionally untagged to maintain backward compatibility with legacy non-tagging devices.
2
Trace the path of untagged frames from Switch-1 to Switch-2.
Frames from VLAN 10 leave Switch-1 untagged. Switch-2 receives the untagged frames and assigns them to its local native VLAN (VLAN 20).
Switches implicitly assume all incoming untagged frames on an 802.1Q trunk belong to whichever VLAN is configured as native on that specific ingress interface.
3
Identify the diagnostic indicators matching the scenario.
Cross-VLAN traffic leakage without a router combined with CDP native VLAN mismatch log warnings confirms a native VLAN configuration mismatch.
Cisco Discovery Protocol (CDP) and LLDP continuously monitor link parameters and report native VLAN mismatches to prevent security and routing anomalies.

Anahtar Kavram

802.1Q Native VLAN Mismatch Dynamics
Soru 1916Soru →

Match each network physical layer diagnostic tool with the troubleshooting scenario it is best suited to resolve.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Optical Power Meter (OPM)
Time-Domain Reflectometer (TDR)
Cable Certifier
Tone Generator and Probe

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Optical Power Meter pairs with measuring optical signal loss across fiber; Time-Domain Reflectometer pairs with locating distance to a copper conductor break; Cable Certifier pairs with verifying Category 6A compliance with TIA/EIA standards; Tone Generator and Probe pairs with tracing an unlabelled drop to a wall port.
Each physical layer tool fulfills a distinct troubleshooting requirement: an Optical Power Meter calculates decibel loss on fiber links; a Time-Domain Reflectometer uses electrical reflections to determine distance to a copper break; a Cable Certifier validates complete TIA/EIA standard parameters like NEXT and attenuation; and a Tone Generator with Probe physically traces unlabelled wire runs.

Adım Adım Çözüm

1
Analyze each physical layer troubleshooting tool and identify its underlying diagnostic mechanism.
Identified light loss measurement for fiber, electrical signal reflection analysis for copper distance-to-fault, compliance sweep testing for Category ratings, and signal modulation tracing for wire identification.
Different physical media and failure modes require distinct diagnostic tool capabilities.
2
Map each tool to its primary diagnostic scenario.
Optical Power Meter maps to fiber optical loss; TDR maps to copper open fault distance; Cable Certifier maps to TIA/EIA standards validation; Tone Generator and Probe maps to cable identification.
Proper tool selection depends directly on the media type (copper vs fiber) and whether the goal is tracing, fault location, or standards certification.

Anahtar Kavram

Physical Cabling Diagnostic Tool Selection
Soru 1917Soru →

A network administrator notices that client workstations can successfully resolve domain names using standard DNS queries. However, full DNS zone transfers (AXFR) between the primary and secondary authoritative DNS servers consistently fail across a newly installed internal firewall. Which of the following transport layer configurations is required on the firewall to allow zone transfers to complete successfully?

Cevabı ve açıklamayı göster

Cevap: Permit traffic on TCP port 53 between the primary and secondary DNS servers.

Cevap

Permitting traffic on TCP port 53 allows the primary and secondary DNS servers to establish a reliable, connection-oriented session needed for transmitting complete DNS zone transfer databases.
DNS relies on UDP port 53 for standard hostname lookups due to low overhead, but uses TCP port 53 for zone transfers (AXFR/IXFR) and responses that exceed standard datagram limits. Allowing TCP port 53 traffic through the firewall enables the secondary DNS server to pull zone data reliably.

Adım Adım Çözüm

1
Analyze the difference between standard DNS lookup traffic and DNS zone replication.
Standard client queries use small UDP datagrams (UDP port 53), while zone transfers (AXFR) send large data structures requiring connection reliability.
UDP packets are limited in size (traditionally 512 bytes without EDNS0) and lack connection state verification for complete database transfers.
2
Identify the protocol and port requirements for DNS zone transfers (AXFR).
Zone transfers strictly require TCP port 53.
TCP ensures ordered delivery, retransmission of lost packets, and supports payloads larger than standard UDP limits.
3
Determine the necessary firewall rule change.
Allow TCP port 53 traffic between the primary and secondary DNS server IP addresses.
Opening TCP port 53 permits the secondary server to initiate and receive full zone transfers.

Anahtar Kavram

DNS Transport Protocols (UDP 53 vs TCP 53)
Tahmini Süre:1m 15s
Soru 1918Soru →

A network technician executes `nslookup -type=TXT _dmarc.example.com` to verify an email authentication policy record. The command returns the following terminal output:

Server: UnKnown
Address: 192.168.1.2

Non-authoritative answer:
_dmarc.example.com text = "v=DMARC1; p=reject;"

Based on this command-line output, which of the following statements correctly interprets the diagnostic result?

Cevabı ve açıklamayı göster

Cevap: The record data was successfully retrieved from a local caching DNS resolver rather than the authoritative DNS server for example.com.

Cevap

The record data was successfully retrieved from a local caching DNS resolver rather than the authoritative DNS server for example.com.
The 'Non-authoritative answer' output header signifies that the server responding to the query (192.168.1.2) obtained the record via recursive resolution or local cache rather than directly holding the authoritative zone files for example.com. The TXT query successfully returned the expected DMARC record.

Adım Adım Çözüm

1
Analyze the output header line 'Server: UnKnown / Address: 192.168.1.2'.
Identifies that the local computer queried the internal DNS server at 192.168.1.2, whose reverse DNS PTR lookup is unconfigured.
Understanding local DNS server settings prevents confusing unmapped server hostnames with query failures.
2
Examine the answer section designation 'Non-authoritative answer:'.
Confirms the response originated from a recursive or caching server rather than the authoritative name server hosting the primary zone.
Non-authoritative answers occur when a resolver holds cached records or queries third-party root/TLD servers on behalf of the client.
3
Evaluate the record payload '_dmarc.example.com text = "v=DMARC1; p=reject;"'.
Confirms valid TXT record contents were successfully fetched.
DMARC policies are properly published within TXT resource records.

Anahtar Kavram

Interpreting nslookup output headers and non-authoritative DNS lookup results
Soru 1919Soru →

An enterprise organization is updating its disaster recovery strategy for an internal human resources application. The Business Impact Analysis (BIA) specifies a Recovery Time Objective (RTO) of 6 hours and a Recovery Point Objective (RPO) of 24 hours. To meet budget constraints, management wants to avoid paying for continuously running duplicate hardware and real-time data replication, but requires pre-routed networking and pre-installed server hardware so that daily backups can be loaded quickly following a disaster. Which of the following recovery site strategies best fulfills these requirements?

Cevabı ve açıklamayı göster

Cevap: Warm site

Cevap

A warm site provides the optimal balance of pre-installed hardware infrastructure and cost savings, allowing system restoration from 24-hour backups within the 6-hour RTO window.
The correct strategy is a warm site. A warm site includes physical space, power, cooling, network connectivity, and pre-installed server hardware. Because data is not synchronized continuously in real time, administrators must restore recent daily backups (matching the 24-hour RPO) onto the hardware during a failover event, which can comfortably be completed within the 6-hour RTO without the high ongoing cost of active hot site replication.

Adım Adım Çözüm

1
Analyze the RTO and RPO requirements
RTO is 6 hours (restoration time window) and RPO is 24 hours (acceptable data loss window).
Understanding recovery metrics determines whether real-time synchronization or periodic backup restoration is needed.
2
Evaluate infrastructure and budget constraints
The solution must avoid running duplicate hardware continuously (ruling out hot and active-active sites) but must have pre-installed hardware to meet 6 hours (ruling out cold sites).
Cold sites take too long to equip (days/weeks), whereas hot/active-active sites are too expensive to run continuously.
3
Select the appropriate recovery site type
A warm site provides pre-configured hardware and network infrastructure ready to receive restored daily (24-hour) backups within the 6-hour target.
Warm sites balance hardware readiness with cost efficiency for moderate RTO/RPO targets.

Anahtar Kavram

Disaster recovery site types and RTO/RPO trade-offs
Soru 1920Soru →

A network administrator attempts to configure Core-Switch-01 to serve as the Spanning Tree Protocol (STP) root bridge for VLAN 50. The administrator executes the command to set the bridge priority for VLAN 50 to 61440. Shortly after, a newly provisioned access switch with factory default settings is connected to the network and unexpectedly assumes the root bridge role for VLAN 50. Which of the following best explains why the access switch became the root bridge instead of Core-Switch-01?

Cevabı ve açıklamayı göster

Cevap: The bridge priority assigned to Core-Switch-01 is numerically higher than the default priority of 32768 on the access switch, and STP prefers the lowest numerical priority value.

Cevap

The bridge priority assigned to Core-Switch-01 is numerically higher than the default priority of 32768 on the access switch, and STP prefers the lowest numerical priority value.
In Spanning Tree Protocol (802.1D / 802.1w), the root bridge election is determined by the lowest Bridge ID (BID). The default bridge priority for switches is 32768 (plus the VLAN ID extension). When the administrator set the core switch priority to 61440, the numerical value was increased instead of decreased. As a result, the newly attached switch with its default priority of 32768 had a lower numerical BID and won the root bridge election.

Adım Adım Çözüm

1
Analyze Spanning Tree Protocol (STP) root bridge selection criteria.
STP elects the switch with the lowest Bridge Identifier (BID) as the root bridge. The BID consists of Bridge Priority (2 bytes) + System ID Extension/VLAN ID + MAC Address (6 bytes).
Lower numerical priority values take precedence over higher numerical values.
2
Compare the configured priority value against the factory default priority.
Core-Switch-01 priority = 61440. Access switch default priority = 32768.
Because 32768 < 61440, the access switch has a superior (lower) priority value.
3
Determine why the access switch assumed the root bridge role.
Configuring a priority of 61440 made Core-Switch-01 less preferred than any switch running default settings (32768). To guarantee root bridge status, the priority should have been set to a lower value such as 4096 or 0.
Correcting the misconfiguration requires assigning a lower numerical priority to the designated core switch.

Anahtar Kavram

Spanning Tree Protocol (STP) Root Bridge Election and Priority Mechanics
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