Switching and bridging in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of a network switch?

A network switch connects devices within a local area network (LAN) and forwards data only to the device that needs it, improving network efficiency.

intermediate

How does a network bridge differ from a switch?

A bridge connects two separate network segments and filters traffic between them based on MAC addresses, while a switch connects multiple devices within a single network segment.

beginner

What is MAC address learning in switching?

MAC address learning is when a switch records the MAC addresses of devices connected to each port to know where to send data frames efficiently.

intermediate

Why is bridging important in network design?

Bridging helps divide a large network into smaller segments, reducing traffic and collisions, which improves overall network performance.

beginner

What happens when a switch receives a frame with an unknown destination MAC address?

The switch forwards the frame to all ports except the one it came from, a process called flooding, to find the destination device.

What device connects multiple devices within the same LAN and forwards data based on MAC addresses?

A Router

B Switch

C Bridge

D Modem

A switch connects devices in a LAN and forwards data frames based on MAC addresses.

Which device is used to connect two separate network segments and reduce traffic between them?

A Switch

B Repeater

C Bridge

D Hub

A bridge connects two network segments and filters traffic to reduce unnecessary data flow.

What is the process called when a switch sends a frame to all ports except the source port?

A Flooding

B Broadcasting

C Routing

D Filtering

Flooding is when a switch sends a frame to all ports except the one it came from to find the destination.

Why do switches learn MAC addresses?

A To forward frames efficiently

B To encrypt data

C To assign IP addresses

D To connect to the internet

Switches learn MAC addresses to know where to send data frames directly, improving efficiency.

What is one benefit of using bridging in a network?

A Increasing network collisions

B Connecting to the internet

C Replacing routers

D Dividing a network into smaller segments

Bridging divides a large network into smaller parts, reducing traffic and collisions.

Explain how a network switch uses MAC addresses to forward data within a LAN.

Think about how the switch remembers device locations.

Describe the role of a network bridge and how it helps improve network performance.

Consider how dividing a network helps.

Practice

1. What is the main purpose of a network switch in a local area network?

easy

A. To block all incoming traffic

B. To send data directly to the intended device

C. To assign IP addresses to devices

D. To connect different networks over the internet

Solution

1. Step 1: Understand the role of a switch

   A switch connects devices within the same network and forwards data only to the device it is meant for.

2. Step 2: Compare with other options

   Assigning IP addresses is done by a DHCP server, connecting different networks is done by routers, and blocking all traffic is not a switch's function.

3. Final Answer:

   To send data directly to the intended device -> Option B

4. Quick Check:

   Switch forwards data to correct device [OK]

Hint: Switch sends data only to the target device [OK]

Common Mistakes:

• Confusing switch with router
• Thinking switch assigns IP addresses
• Believing switch blocks all traffic

2. Which of the following is the correct function of a network bridge?

easy

A. To connect and filter traffic between two network segments

B. To assign IP addresses to devices

C. To provide wireless access to devices

D. To encrypt data packets

Solution

1. Step 1: Define the role of a bridge

   A bridge connects two or more network segments and controls the flow of data between them by filtering traffic.

2. Step 2: Eliminate incorrect options

   Assigning IP addresses is DHCP's job, wireless access is provided by access points, and encryption is done by security protocols, not bridges.

3. Final Answer:

   To connect and filter traffic between two network segments -> Option A

4. Quick Check:

   Bridge connects segments and filters traffic [OK]

Hint: Bridge links segments and filters data flow [OK]

Common Mistakes:

• Confusing bridge with DHCP server
• Thinking bridge provides wireless access
• Assuming bridge encrypts data

3. Consider a network with two segments connected by a bridge. If a device on segment A sends data to a device on segment B, what will the bridge do?

medium

A. It will forward the data only if the destination is on segment B

B. It will block the data to prevent traffic

C. It will broadcast the data to all devices on both segments

D. It will assign a new IP address to the data packet

Solution

1. Step 1: Understand bridge filtering

   The bridge learns which devices are on each segment and forwards data only to the segment where the destination device is located.

2. Step 2: Analyze options

   Blocking data prevents communication, broadcasting to all devices wastes bandwidth, and assigning IP addresses is not a bridge function.

3. Final Answer:

   It will forward the data only if the destination is on segment B -> Option A

4. Quick Check:

   Bridge forwards data only to correct segment [OK]

Hint: Bridge forwards data only to destination segment [OK]

Common Mistakes:

• Thinking bridge blocks all data
• Assuming bridge broadcasts to all devices
• Confusing bridge with DHCP server

4. A network administrator sets up a switch but notices that data is being sent to all devices instead of just the intended one. What is the most likely cause?

medium

A. The switch is assigning IP addresses incorrectly

B. The switch is blocking all traffic due to security settings

C. The switch is operating in hub mode or has a faulty MAC address table

D. The switch is connected to a wireless access point

Solution

1. Step 1: Identify switch behavior

   If a switch sends data to all devices, it behaves like a hub, often due to a missing or corrupted MAC address table.

2. Step 2: Rule out other causes

   Blocking all traffic would stop communication, IP assignment is unrelated to forwarding, and wireless access points do not cause this behavior.

3. Final Answer:

   The switch is operating in hub mode or has a faulty MAC address table -> Option C

4. Quick Check:

   Switch flooding due to MAC table issue [OK]

Hint: Switch flooding means MAC table problem or hub mode [OK]

Common Mistakes:

• Confusing IP assignment with forwarding issues
• Thinking wireless access point causes flooding
• Assuming security blocks cause flooding

5. In a large office, two separate departments have their own network segments connected by a bridge. The bridge is configured to filter traffic between them. Which of the following is a key benefit of this setup?

hard

A. It automatically assigns IP addresses to all devices in both departments

B. It allows all devices to receive every data packet for better communication

C. It encrypts all data passing between the two segments

D. It reduces unnecessary traffic between departments, improving network performance

Solution

1. Step 1: Understand bridge filtering benefits

   By filtering traffic, the bridge prevents unnecessary data from crossing between segments, reducing congestion and improving speed.

2. Step 2: Eliminate incorrect options

   Allowing all devices to receive all packets causes congestion, IP assignment is DHCP's role, and encryption is handled by security protocols, not bridges.

3. Final Answer:

   It reduces unnecessary traffic between departments, improving network performance -> Option D

4. Quick Check:

   Bridge filtering reduces traffic [OK]

Hint: Bridge filtering cuts traffic, boosts speed [OK]

Common Mistakes:

• Thinking bridge broadcasts all data
• Confusing bridge with DHCP server
• Assuming bridge encrypts data