Ethernet Fundamentals

Correct Answer: B (Xerox)
Ethernet was developed at Xerox PARC (Palo Alto Research Center) in 1973 by Robert Metcalfe and David Boggs. It was later standardized as IEEE 802.3.

Correct Answer: B (48 bits)
Ethernet MAC addresses are 48 bits (6 bytes) long, typically represented as six groups of two hexadecimal digits separated by colons or hyphens (e.g., 00:1A:2B:3C:4D:5E).

Correct Answer: C (Bus topology)
10BASE5 (Thick Ethernet) used a bus topology where all devices connected to a single coaxial cable backbone. Modern Ethernet uses star topology with switches.

Correct Answer: B (1 Gbps)
Gigabit Ethernet (IEEE 802.3ab for copper, 802.3z for fiber) operates at 1 Gbps (1,000 Mbps). It maintains the same frame format as earlier Ethernet standards for backward compatibility.

Correct Answer: B (Collision Detection)
CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection. It was used in early shared Ethernet to detect when two stations transmitted simultaneously and handle the collision.

Correct Answer: B (64 bytes)
The minimum Ethernet frame size is 64 bytes (from destination MAC to FCS). This includes 14 bytes header, 46 bytes minimum payload, and 4 bytes FCS. The minimum size ensures proper collision detection.

Correct Answer: B (Media Access Control)
The MAC sublayer handles frame encapsulation, MAC addressing, and error detection (FCS). LLC handles multiplexing different network layer protocols.

Correct Answer: B (Twisted pair)
The "T" stands for Twisted pair. 100BASE-TX uses two pairs of Category 5 UTP cable. "F" would indicate fiber optic, while "2" or "5" indicated coaxial in earlier standards.

Correct Answer: B (Error detection using CRC)
The FCS is a 4-byte CRC-32 checksum used to detect transmission errors. The receiving station recalculates the CRC and compares it to the FCS field; if they differ, the frame is discarded.

Correct Answer: B (CSMA/CD)
Full-duplex Ethernet uses separate channels for transmit and receive, eliminating collisions entirely. Therefore, CSMA/CD (Collision Detection) is not needed, allowing simultaneous two-way communication.

Correct Answer: A (1500 bytes)
The standard Ethernet MTU is 1500 bytes (payload only). While Jumbo frames (9000 bytes) exist, they are non-standard. 1518 bytes is the maximum total frame size including headers.

Correct Answer: B (100BASE-TX)
Auto-Negotiation was introduced with Fast Ethernet (IEEE 802.3u) to allow devices to automatically select the best common mode of operation (speed, duplex) without manual configuration.