Correct Answers: C. Network interface card failure and D. Incorrect or damaged cables.

The bottom-up troubleshooting methodology follows the Open Systems Interconnection (OSI) reference model, beginning at Layer 1 (Physical Layer) and progressively moving toward higher layers.

The primary objective is to identify physical connectivity problems before investigating network configuration, transport protocols, or application services.

C. Network interface card failure — Correct

A faulty Network Interface Card (NIC) can prevent a computer from establishing a physical network connection. Technicians should examine NIC status indicators, verify link detection, inspect physical connections, and test the adapter using appropriate diagnostic tools.

D. Incorrect or damaged cables — Correct

Damaged Ethernet cables, defective connectors, improper cable termination, or disconnected cables can prevent reliable signal transmission. Technicians should inspect cable connections, examine link indicators, and replace questionable cables with known-good alternatives.

Why the other options are incorrect:

A. An incorrect network password involves authentication, which is investigated after physical connectivity.

B. An incorrect IP address configuration relates to Layer 3 networking.

E. An incorrect DNS server address affects name resolution, which is investigated at higher layers.

Therefore, C and D are the correct answers because both concern fundamental physical-layer connectivity. Cisco Press explicitly identifies the Physical layer as the starting point for bottom-up troubleshooting.

Cisco Press+1