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Zorluk: Çok zorWired and Wireless Network Issues

Match each wired or wireless network troubleshooting scenario on the left with its most likely underlying root cause on the right.

  • A laptop displays full Wi-Fi signal strength but receives an IPv4 address of 169.254.88.105 and shows 'No Internet Access'.DHCP server unreachability or scope exhaustion causing the client to self-assign an APIPA address.
  • Users in a dense office experience heavy packet loss and degraded wireless performance when nearby access points are configured on Wi-Fi channels 1, 3, and 6.Co-channel and adjacent-channel interference (ACI) resulting from non-standard channel selection in the 2.4 GHz band.
  • A desktop workstation connected via twisted-pair copper cable experiences severe latency and excessive late collisions after its NIC speed is manually forced to 1 Gbps Full-Duplex.Duplex mismatch caused by one endpoint being hardcoded while the connecting switch port uses auto-negotiation.
  • A newly deployed Ethernet wall outlet provides no link light at either the workstation NIC or the switch port despite the switch port being enabled.Physical layer failure such as a pin mismatch, cut conductor in the cat cable run, or improperly crimped RJ-45 connector.

Cevap

Each scenario maps to its Layer 1–3 network troubleshooting root cause: APIPA indicates unreachable DHCP (left_1 -> right_1); channel 3 causes adjacent-channel interference in 2.4 GHz (left_2 -> right_2); manual NIC speed settings cause duplex mismatches with auto-negotiating ports (left_3 -> right_3); and absence of link lights signals a physical layer copper/termination fault (left_4 -> right_4).
The correct pairings accurately match common CompTIA A+ network symptoms to their definitive causes: APIPA (169.254.x.x) directly signals DHCP failure; channel 3 creates adjacent-channel wireless interference; forced NIC speed/duplex against an auto-negotiating switch causes duplex mismatches and late collisions; and dark link LEDs point to physical layer cabling or pin defects.

Adım Adım Çözüm

1
Analyze the IP address output for the laptop scenario.
Recognize that 169.254.88.105 belongs to the APIPA pool, indicating a DHCP request failure.
When a client fails to receive a response to a DHCPDISCOVER query, APIPA self-assigns an address in 169.254.0.0/16.
2
Evaluate the wireless channel topology.
Identify channel 3 as an overlapping channel that violates the 1-6-11 non-overlapping rule in 2.4 GHz spectrum.
Adjacent channels share spectrum frequencies, creating cross-talk and transmission collisions.
3
Diagnose the Ethernet collision and duplex behavior.
Determine that manual configuration on one end forces the auto-negotiating partner into half-duplex mode.
IEEE standards specify that auto-negotiation defaults to half-duplex if duplex signals are not detected from the peer.
4
Inspect the physical connection status.
Correlate missing link lights on an active port with physical layer wiring or pin issues.
Link status LEDs require unbroken copper paths and proper pinouts to establish electrical signals.

Anahtar Kavram

Wired and Wireless Physical and Logical Troubleshooting
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Konular

Wired and Wireless Network Issues

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