CCNA 1 v7.02 & v8 (ITN) Modules 4 - 7: Ethernet Concepts Exam Answers (Full Bank)

Complete question bank for CCNA 1 (ITN v7.02/v8) Modules 4 – 7: Ethernet Concepts & Layer 2 Switching Exam.

📥 Download CCNA 1 v7.02 & v8 (ITN) Modules 4 - 7: Ethernet Concepts Exam Answers (Full Bank) Packet Tracer (.PKA) & Verified PDF Guide

Includes complete Cisco NetAcad v7.02 / v8 topology file (.pka) and IOS CLI configuration script.

Verified Cisco NetAcad Exam Questions (15 Core Questions + Explanations)

Question 1 What is the purpose of the FCS field in an Ethernet frame?

A. To obtain the MAC address of the sending node
B. To verify the logical address of the sending node
C. To compute the CRC header for the data field
D. To determine if errors occurred in the transmission and reception of the frame

✔ Correct Answer: D. To determine if errors occurred in the transmission and reception of the frame

Technical Explanation: The Frame Check Sequence (FCS) trailer uses a 32-bit Cyclic Redundancy Check (CRC) calculation so the receiving NIC can detect corrupted frames and drop them.

Question 2 Which switching method drops frames that fail the FCS check?

A. Store-and-forward switching
B. Cut-through switching
C. Fast-forward switching
D. Borderless switching

✔ Correct Answer: A. Store-and-forward switching

Technical Explanation: Store-and-forward switching buffers the entire Ethernet frame, calculates the CRC against the FCS trailer, and discards any corrupted frames or runts/giants before forwarding.

Question 3 What is the auto-MDIX feature on a Cisco Catalyst switch?

A. Automatic configuration of an interface for 10/100/1000 Mb/s operation
B. Automatic configuration of an interface for a straight-through or a crossover Ethernet cable connection
C. Automatic configuration of full-duplex operation over a single optical cable
D. The ability to turn a switch interface on or off if a loop is detected

✔ Correct Answer: B. Automatic configuration of an interface for a straight-through or a crossover Ethernet cable connection

Technical Explanation: Auto-MDIX detects the required cable pinout (transmit/receive pairs) and automatically adjusts the port internally, eliminating the need to worry about crossover vs. straight-through cables.

Question 4 What will a host on an Ethernet network do if it receives a frame with a unicast destination MAC address that does not match its own MAC address?

A. It will discard the frame.
B. It will forward the frame to the next host.
C. It will remove the frame from the media.
D. It will strip off the data-link frame to check the destination IP address.

✔ Correct Answer: A. It will discard the frame.

Technical Explanation: When a NIC receives an Ethernet frame whose destination MAC does not match the NIC's burned-in MAC, broadcast (FF-FF-FF-FF-FF-FF), or subscribed multicast MAC, it drops the frame at Layer 2 without interrupting the CPU.

Question 5 Which two statements describe the features or functions of the Logical Link Control (LLC) sublayer in Ethernet standards? (Choose two.)

A. Logical Link Control is implemented in software.
B. Logical Link Control is specified in the IEEE 802.3 standard.
C. The LLC sublayer adds a header and a trailer to the data.
D. The Data Link layer uses LLC to communicate with the upper layers of the protocol suite.
E. LLC is responsible for the placement and retrieval of frames on and off the media.

✔ Correct Answer: A. Logical Link Control is implemented in software. & D. The Data Link layer uses LLC to communicate with the upper layers of the protocol suite.

Technical Explanation: The IEEE 802.2 LLC sublayer is implemented in software/drivers and identifies which Network Layer protocol (IPv4, IPv6, ARP) is encapsulated inside the frame.

Question 6 What is the minimum Ethernet frame size that will not be discarded by the receiver as a runt frame?

A. 46 bytes
B. 64 bytes
C. 128 bytes
D. 1518 bytes

✔ Correct Answer: B. 64 bytes

Technical Explanation: The valid IEEE 802.3 Ethernet frame size ranges from 64 bytes (minimum) to 1518 bytes (maximum, excluding VLAN tagging). Any frame smaller than 64 bytes is discarded as a collision fragment (runt).

Question 7 How does a Layer 2 switch build its MAC address table?

A. By inspecting the destination MAC address of incoming frames.
B. By inspecting the source MAC address of incoming frames and recording the ingress port.
C. By sending ARP broadcasts out all active switch ports.
D. By downloading the table from the default gateway router.

✔ Correct Answer: B. By inspecting the source MAC address of incoming frames and recording the ingress port.

Technical Explanation: Switches learn MAC addresses dynamically by reading the Source MAC address of every incoming frame and mapping it to the ingress port in the CAM table.

Question 8 What is the special destination MAC address used by an IPv4 broadcast Ethernet frame?

A. 00-00-00-00-00-00
B. FF-FF-FF-FF-FF-FF
C. 01-00-5E-00-00-01
D. 33-33-00-00-00-01

✔ Correct Answer: B. FF-FF-FF-FF-FF-FF

Technical Explanation: An Ethernet broadcast frame uses a destination MAC address of all 1s in binary (FF-FF-FF-FF-FF-FF in hexadecimal), which causes switches to flood it out all ports in the VLAN.

Question 9 What is the primary benefit of twisting the wire pairs inside a UTP Ethernet cable?

A. It makes the copper wires stronger against physical pulling.
B. It reduces crosstalk and electromagnetic interference (EMI/RFI) through magnetic field cancellation.
C. It allows more wires to fit inside an RJ-45 connector.
D. It increases the voltage level of the electrical signal.

✔ Correct Answer: B. It reduces crosstalk and electromagnetic interference (EMI/RFI) through magnetic field cancellation.

Technical Explanation: Twisting opposing circuit wires together causes their electromagnetic fields to cancel each other out, protecting the signal from external EMI and internal pair-to-pair crosstalk.

Question 10 Why is Single-Mode Fiber (SMF) preferred over Multimode Fiber (MMF) for long-distance campus backbones and WAN links?

A. SMF uses cheaper LED light sources.
B. SMF has a much larger core diameter (62.5 microns).
C. SMF uses a laser light source and a single light path (9-micron core), eliminating modal dispersion over distances up to tens of kilometers.
D. SMF does not require glass cladding.

✔ Correct Answer: C. SMF uses a laser light source and a single light path (9-micron core), eliminating modal dispersion over distances up to tens of kilometers.

Technical Explanation: Single-mode fiber has a tiny 9-micron core that allows only a single ray of laser light to travel straight down the fiber, preventing dispersion and supporting long-haul links.

Question 11 What is the default aging timer for dynamic entries in a Cisco Catalyst switch MAC address table?

A. 30 seconds
B. 180 seconds
C. 300 seconds (5 minutes)
D. 3600 seconds (1 hour)

✔ Correct Answer: C. 300 seconds (5 minutes)

Technical Explanation: By default, Cisco switches keep dynamically learned MAC address entries in the CAM table for 300 seconds (5 minutes) after the last frame is received from that source MAC.

Question 12 Which cut-through switching method offers the lowest latency by forwarding a frame immediately after reading the 6-byte destination MAC address?

A. Fragment-free switching
B. Fast-forward switching
C. Store-and-forward switching
D. CRC-checked switching

✔ Correct Answer: B. Fast-forward switching

Technical Explanation: Fast-forward switching begins forwarding the frame as soon as the destination MAC address is read, offering the lowest possible latency (whereas fragment-free waits for the first 64 bytes).

Question 13 Which Layer 2 media access control method is used by 802.11 Wireless LANs (Wi-Fi) to avoid collisions on shared half-duplex radio frequencies?

A. CSMA/CD
B. CSMA/CA
C. Token Passing
D. Full-Duplex Point-to-Point

✔ Correct Answer: B. CSMA/CA

Technical Explanation: Wireless networks operate in half-duplex and cannot detect collisions while transmitting, so they use Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) and RTS/CTS.

Question 14 What happens when one side of an Ethernet link is configured for Full-Duplex and the other side is set to Half-Duplex?

A. The link automatically negotiates 10 Gbps speed.
B. A duplex mismatch occurs, causing late collisions, FCS errors, and severely degraded throughput.
C. Both ports immediately enter the err-disabled state.
D. The link converts to a Layer 3 routed port.

✔ Correct Answer: B. A duplex mismatch occurs, causing late collisions, FCS errors, and severely degraded throughput.

Technical Explanation: A duplex mismatch causes the full-duplex end to transmit at any time while the half-duplex end sees simultaneous transmissions as collisions, resulting in late collisions and packet loss.

Question 15 Which destination MAC address prefix is reserved for IPv4 multicast frames?

A. 01-00-5E
B. 33-33-00
C. FF-FF-FF
D. FE-80-00

✔ Correct Answer: A. 01-00-5E

Technical Explanation: IPv4 multicast packets map their lower 23 bits into the Ethernet MAC address prefix 01-00-5E-xx-xx-xx (whereas IPv6 multicast uses 33-33-xx-xx-xx-xx).

Modules 4-7 Ethernet & MAC Address Table Verification CLI

Cisco IOS CLI - Verification & Lab Script

Switch# show interfaces GigabitEthernet0/1
Switch# show mac address-table dynamic
Switch# clear mac address-table dynamic

Cisco CCNA 200-301 v1.1 & NetAcad v7.02 / v8 Exam Portal

CCNA 1 v7.02 & v8 (ITN) Modules 4 - 7: Ethernet Concepts Exam Answers (Full Bank)

Verified Cisco NetAcad Exam Questions (15 Core Questions + Explanations)

Modules 4-7 Ethernet & MAC Address Table Verification CLI

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