Distributed computing concept in Intro to Computing - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is distributed computing?

Distributed computing is a way to connect many computers to work together on a task, sharing the work to finish faster or handle bigger problems.

beginner

Name one real-life example of distributed computing.

The internet is a real-life example where many computers around the world share information and work together to provide services like websites and email.

beginner

Why do distributed systems use multiple computers instead of one?

Using many computers helps handle bigger tasks, improves speed, and keeps the system working even if one computer fails.

intermediate

What is a key challenge in distributed computing?

A key challenge is making sure all computers communicate well and agree on the results, even if some computers are slow or fail.

beginner

Explain distributed computing using a real-world analogy.

Imagine a group of friends building a large puzzle together. Each friend works on a small part, then they combine their pieces to complete the puzzle faster than one person alone.

What is the main goal of distributed computing?

A To slow down processing

B To share work among many computers

C To avoid using computers

D To use only one powerful computer

Distributed computing shares work among many computers to complete tasks faster or handle larger problems.

Which of these is a challenge in distributed computing?

A Making sure all computers agree on results

B Using only one computer

C Avoiding communication between computers

D Ignoring computer failures

Ensuring all computers communicate and agree on results is a key challenge in distributed computing.

In distributed computing, what happens if one computer fails?

A The whole system stops immediately

B The failed computer is ignored forever

C The task is deleted

D Other computers continue working

Distributed systems are designed so other computers continue working even if one fails.

Which real-world system is an example of distributed computing?

A The internet

B A calculator

C A single desktop computer

D A standalone printer

The internet connects many computers worldwide, making it a prime example of distributed computing.

What does distributed computing improve compared to using one computer?

A Only reliability

B Only speed

C Speed and reliability

D Neither speed nor reliability

Distributed computing improves both speed and reliability by sharing work and handling failures.

Describe distributed computing and explain why it is useful.

Think about how many computers can work together like a team.

Give a real-life analogy for distributed computing and explain how it helps understand the concept.

Imagine friends working together on a big task.

Practice

1. What is the main idea behind distributed computing?

easy

A. Splitting a big task into smaller parts and running them on many computers

B. Using one very fast computer to do all the work

C. Storing all data on a single computer

D. Running programs without any network connection

Solution

1. Step 1: Understand the concept of distributed computing

   Distributed computing means breaking a large problem into smaller tasks that multiple computers can work on at the same time.

2. Step 2: Compare options with the concept

   Splitting a big task into smaller parts and running them on many computers matches this idea exactly. Options A, C, and D do not involve splitting tasks or using multiple computers.

3. Final Answer:

   Splitting a big task into smaller parts and running them on many computers -> Option A

4. Quick Check:

   Distributed computing = splitting tasks across computers [OK]

Hint: Distributed means many computers share the work [OK]

Common Mistakes:

• Thinking distributed means one computer does all work
• Confusing distributed computing with offline computing
• Assuming data is stored on only one machine

2. Which of the following is the correct way computers in a distributed system communicate?

easy

A. By printing results on paper

B. By sharing the same keyboard and mouse

C. By using the same hard drive directly

D. By sending messages over a network

Solution

1. Step 1: Identify communication methods in distributed systems

   Computers in distributed systems communicate by exchanging messages through a network connection.

2. Step 2: Evaluate each option

   By sending messages over a network correctly describes message passing over a network. Options B, C, and D are not practical or correct communication methods for distributed computing.

3. Final Answer:

   By sending messages over a network -> Option D

4. Quick Check:

   Communication in distributed computing = message passing [OK]

Hint: Distributed computers talk by sending messages [OK]

Common Mistakes:

• Thinking they share hardware directly
• Assuming physical devices like keyboard are shared
• Confusing communication with printing output

3. Consider a distributed system where 4 computers each process 25% of a task simultaneously. If one computer fails, what is the likely effect?

medium

A. The whole task stops immediately

B. The task may slow down or need reprocessing

C. The failed computer finishes the task alone

D. The task completes faster

Solution

1. Step 1: Understand fault tolerance in distributed systems

   If one computer fails, the system may slow down because the failed part needs to be redone or handled by others.

2. Step 2: Analyze each option

   The task may slow down or need reprocessing correctly states the task may slow or need reprocessing. The whole task stops immediately is too absolute; many systems handle failures. The task completes faster is incorrect because failure does not speed up work. The failed computer finishes the task alone is impossible since the failed computer cannot work.

3. Final Answer:

   The task may slow down or need reprocessing -> Option B

4. Quick Check:

   Failure in distributed system = slowdown or rework [OK]

Hint: Failure causes delay or retry, not speedup [OK]

Common Mistakes:

• Assuming failure stops all work immediately
• Thinking failure makes task faster
• Believing failed computers still work

4. A distributed system is designed to split a task into 3 parts, but the code only sends messages to 2 computers. What is the main problem?

medium

A. One part of the task is not assigned or processed

B. All parts are processed twice

C. The system runs faster than expected

D. The network connection is too fast

Solution

1. Step 1: Identify the issue with message sending

   If messages are sent to only 2 computers but the task has 3 parts, one part is left unassigned.

2. Step 2: Evaluate the impact

   One part of the task is not assigned or processed correctly states the missing part is not processed. Options A, B, and D do not relate to the problem described.

3. Final Answer:

   One part of the task is not assigned or processed -> Option A

4. Quick Check:

   Missing messages = missing task part [OK]

Hint: Each task part needs a message to a computer [OK]

Common Mistakes:

• Assuming unassigned parts are processed anyway
• Thinking parts get duplicated automatically
• Ignoring message-to-task part matching

5. You want to speed up processing a large dataset by using distributed computing. Which approach best ensures reliability if some computers might fail?

hard

A. Run the same task on all computers without splitting data

B. Assign the entire dataset to one computer only

C. Split data into parts and assign each part to multiple computers for backup

D. Use only one computer and ignore failures

Solution

1. Step 1: Understand reliability in distributed computing

   To handle failures, tasks or data parts should be duplicated on multiple computers as backup.

2. Step 2: Analyze options for reliability

   Split data into parts and assign each part to multiple computers for backup uses redundancy to ensure reliability. Options B and D rely on one computer, risking failure. Run the same task on all computers without splitting data wastes resources and does not split data efficiently.

3. Final Answer:

   Split data into parts and assign each part to multiple computers for backup -> Option C

4. Quick Check:

   Reliability = redundancy in distributed tasks [OK]

Hint: Backup tasks on multiple computers for safety [OK]

Common Mistakes:

• Ignoring backup and redundancy
• Using single computer for big tasks
• Duplicating entire dataset on all computers inefficiently