Ethernet protocol basics in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

📋 Factual

intermediate

What is the primary function of the Ethernet protocol?

Choose the best description of what Ethernet does in a computer network.

A It defines how devices format and transmit data over a local network.

B It encrypts data to secure communication over the internet.

C It assigns IP addresses to devices on a network.

D It manages wireless connections between devices.

💡 Hint

Think about what Ethernet controls in a wired network.

Ethernet is a set of rules that controls how data is packaged and sent over wired local networks.

🧠 Conceptual

intermediate

How does Ethernet handle data collisions on a shared network?

What method does Ethernet use to manage when two devices send data at the same time?

A It uses a central controller to schedule transmissions.

B It encrypts the data to prevent collisions.

C It uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to detect and manage collisions.

D It assigns fixed time slots to devices to avoid collisions.

💡 Hint

Think about how Ethernet devices listen before sending data.

Ethernet uses CSMA/CD, where devices listen before sending and detect collisions to resend data later.

🔍 Analysis

advanced

What will be the result if two Ethernet devices transmit data simultaneously on a half-duplex network?

Consider two devices sending data at the same time on a half-duplex Ethernet network. What happens?

A Both devices transmit successfully without any interference.

B A collision occurs, causing both devices to stop and retry sending after a random delay.

C One device automatically takes priority and the other waits.

D The network switches to full-duplex mode to avoid collision.

💡 Hint

Recall how half-duplex Ethernet manages simultaneous transmissions.

In half-duplex, simultaneous transmissions cause collisions, so devices stop and retry after waiting.

❓ Comparison

advanced

Which statement correctly compares full-duplex and half-duplex Ethernet?

Choose the correct difference between full-duplex and half-duplex Ethernet communication.

A Full-duplex allows sending and receiving data at the same time; half-duplex allows only one direction at a time.

B Half-duplex allows simultaneous send and receive; full-duplex only one direction at a time.

C Both full-duplex and half-duplex allow simultaneous two-way communication.

D Half-duplex uses fiber optic cables; full-duplex uses copper cables.

💡 Hint

Think about whether data can flow both ways at once.

Full-duplex Ethernet can send and receive data simultaneously, while half-duplex cannot.

❓ Reasoning

expert

Why is the Ethernet frame's preamble important in communication?

What role does the preamble in an Ethernet frame play during data transmission?

A It contains the destination MAC address for routing the frame.

B It signals the end of the data frame to the receiver.

C It encrypts the data to protect it from interception.

D It synchronizes the receiver's clock to the sender's timing before actual data arrives.

💡 Hint

Consider what must happen before the receiver can correctly read the data bits.

The preamble helps the receiver align its timing with the sender to read the data correctly.

Practice

1. What is the primary purpose of the Ethernet protocol in computer networks?

easy

A. To define how devices communicate over a local area network

B. To assign IP addresses to devices

C. To encrypt data sent over the internet

D. To manage wireless connections

Solution

1. Step 1: Understand Ethernet's role

   Ethernet is a protocol used mainly for communication within local area networks (LANs).

2. Step 2: Compare with other network functions

   Assigning IP addresses is done by DHCP, encryption by security protocols, and wireless management by Wi-Fi standards.

3. Final Answer:

   To define how devices communicate over a local area network -> Option A

4. Quick Check:

   Ethernet = LAN communication [OK]

Hint: Ethernet is about local network communication [OK]

Common Mistakes:

• Confusing Ethernet with IP address assignment
• Thinking Ethernet manages wireless connections
• Assuming Ethernet encrypts data

2. Which part of an Ethernet frame contains the unique hardware address of the sending device?

easy

A. Payload

B. Destination IP address

C. Frame Check Sequence

D. Source MAC address

Solution

1. Step 1: Identify frame components

   An Ethernet frame includes source and destination MAC addresses, payload, and error-checking fields.

2. Step 2: Locate the sender's hardware address

   The source MAC address field holds the unique hardware address of the sending device.

3. Final Answer:

   Source MAC address -> Option D

4. Quick Check:

   Sender's hardware = Source MAC address [OK]

Hint: Source MAC = sender's hardware address [OK]

Common Mistakes:

• Confusing payload with address fields
• Mixing IP address with MAC address
• Thinking Frame Check Sequence holds addresses

3. Consider this simplified Ethernet frame structure:
Destination MAC | Source MAC | Type | Payload | CRC
Which part is responsible for detecting errors in the frame?

medium

A. Type

B. Payload

C. CRC

D. Source MAC

Solution

1. Step 1: Understand frame fields

   The CRC (Cyclic Redundancy Check) field is used to detect errors in the frame data.

2. Step 2: Differentiate other fields

   Type indicates the protocol, Payload carries data, and Source MAC is the sender's address, none detect errors.

3. Final Answer:

   CRC -> Option C

4. Quick Check:

   Error detection = CRC [OK]

Hint: CRC checks for errors in Ethernet frames [OK]

Common Mistakes:

• Confusing Type field with error detection
• Assuming Payload includes error checking
• Mixing Source MAC with error detection

4. A network technician notices that Ethernet frames are being dropped due to collisions. Which Ethernet feature helps to reduce collisions in a shared network?

medium

A. MAC Address Filtering

B. Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

C. IP Addressing

D. Encryption

Solution

1. Step 1: Identify collision handling method

   CSMA/CD is the Ethernet protocol feature that listens before sending and detects collisions to reduce frame loss.

2. Step 2: Eliminate unrelated options

   IP addressing manages network layer routing, MAC filtering controls access, and encryption secures data, none reduce collisions.

3. Final Answer:

   Carrier Sense Multiple Access with Collision Detection (CSMA/CD) -> Option B

4. Quick Check:

   Collision reduction = CSMA/CD [OK]

Hint: CSMA/CD manages collisions in Ethernet [OK]

Common Mistakes:

• Confusing IP addressing with collision control
• Thinking MAC filtering prevents collisions
• Assuming encryption affects collisions

5. You want to design a network where devices communicate using Ethernet frames but avoid collisions entirely. Which modern Ethernet technology should you choose?

hard

A. Full-duplex Ethernet with switches

B. Half-duplex Ethernet with hubs

C. Wireless Ethernet with CSMA/CA

D. Token Ring Ethernet

Solution

1. Step 1: Understand collision domains

   Half-duplex Ethernet with hubs shares the medium, causing collisions; full-duplex with switches separates devices.

2. Step 2: Evaluate options for collision avoidance

   Full-duplex Ethernet with switches allows simultaneous send/receive without collisions. Wireless uses CSMA/CA, not Ethernet. Token Ring is a different protocol.

3. Final Answer:

   Full-duplex Ethernet with switches -> Option A

4. Quick Check:

   No collisions = Full-duplex + switches [OK]

Hint: Switches + full-duplex avoid Ethernet collisions [OK]

Common Mistakes:

• Choosing hubs which cause collisions
• Confusing wireless CSMA/CA with Ethernet collision control
• Thinking Token Ring is Ethernet