Match each network troubleshooting symptom to its underlying root cause.
- A workstation displays an IPv4 address of 169.254.112.85 with a subnetwork mask of 255.255.0.0 and cannot reach external subnets.DHCP server unreachability or scope exhaustion causing the client to self-assign an APIPA address.
- A desktop computer connected via unshielded twisted-pair (UTP) cabling experiences intermittent link drops whenever adjacent industrial HVAC equipment turns on.Electromagnetic Interference (EMI) introducing signal noise and bit errors along the copper cable run.
- A wireless laptop maintains high RSSI (-50 dBm) on a 2.4 GHz Wi-Fi network but suffers from high frame loss and poor throughput near legacy cordless devices.ISM band frequency interference degrading the Signal-to-Noise Ratio (SNR) on the 2.4 GHz channel.
- A workstation plugged into the pass-through port of a VoIP phone loses network access immediately when port security is enabled on the managed switch.Maximum MAC address limit violation on the switch port configured for port security.
Cevap
169.254.x.x address maps to DHCP server unreachability/scope exhaustion; UTP link drops near HVAC equipment map to Electromagnetic Interference (EMI); 2.4 GHz throughput issues near legacy cordless devices map to ISM band frequency interference; PC losing access through VoIP phone pass-through maps to maximum MAC address limit violation.
Each symptom directly corresponds to its characteristic OSI layer failure: 169.254.x.x addresses indicate DHCP unreachability (APIPA); UTP cable disruption coinciding with motor start-up indicates Electromagnetic Interference; 2.4 GHz performance degradation near non-Wi-Fi transmitters indicates ISM band RF noise; and disabling pass-through traffic under port security indicates a maximum MAC address threshold violation.
Adım Adım Çözüm
Anahtar Kavram
Identifying layer 1 through layer 3 wired and wireless network failure modes.