Why social media tests multiple design skills in HLD - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why does social media require multiple design skills?

Social media platforms involve many features like user profiles, feeds, messaging, and notifications. Which reason best explains why designing social media tests multiple system design skills?

A Because social media platforms focus only on visual design and ignore backend architecture.

B Because social media only needs simple database queries and static pages, so design skills are minimal.

C Because social media systems combine data storage, real-time updates, scalability, and user interaction, requiring diverse design approaches.

D Because social media systems are small and do not require handling many users or data.

💡 Hint

Think about the different parts a social media app must handle simultaneously.

Social media platforms must handle large user bases, real-time data, complex interactions, and scalable storage. This combination tests multiple design skills like database design, caching, load balancing, and API design.

❓ Architecture

intermediate

Which component is essential for real-time updates in social media?

Social media platforms show live notifications and message updates. Which architectural component is most critical to support this real-time behavior?

A A batch job that updates notifications once a day.

B A message queue or pub/sub system to push updates instantly to users.

C A static HTML page refreshed manually by users.

D A relational database without caching or messaging.

💡 Hint

Real-time means updates happen immediately without user refresh.

Message queues or publish-subscribe systems allow the backend to push updates to clients instantly, enabling real-time notifications and messaging.

❓ scaling

advanced

How to handle millions of users posting simultaneously?

Social media platforms must support millions of users posting content at the same time. Which scaling strategy best supports this?

A Use a single powerful server to handle all requests.

B Store all posts in a local file system without replication.

C Limit the number of users allowed to post at once to reduce load.

D Use horizontal scaling with load balancers and distributed databases to spread the load.

💡 Hint

Think about spreading work across many machines instead of relying on one.

Horizontal scaling with load balancers and distributed databases allows the system to handle large traffic by distributing requests and data storage across many servers.

❓ tradeoff

advanced

Tradeoff between consistency and availability in social media feeds

Social media feeds must show recent posts quickly but sometimes may show slightly outdated data. What tradeoff explains this design choice?

A Choosing eventual consistency over strict consistency to improve availability and speed.

B Choosing strict consistency and sacrificing availability completely.

C Ignoring consistency and showing random data to users.

D Always blocking users until all data is perfectly synced.

💡 Hint

Think about how systems balance showing data fast versus perfectly up-to-date.

Eventual consistency allows the system to serve data quickly and remain available, accepting that some data may be slightly out of date temporarily.

❓ estimation

expert

Estimate storage needed for 1 billion social media posts

Assume each social media post averages 2 MB in size. Estimate the total storage needed to store 1 billion posts, including 20% overhead for indexing and metadata.

A Approximately 2.4 petabytes (PB)

B Approximately 20 petabytes (PB)

C Approximately 200 terabytes (TB)

D Approximately 24 terabytes (TB)

💡 Hint

Calculate base size then add 20% overhead.

1 billion posts * 2 MB = 2,000,000,000 MB = ~1.86 PB. Adding 20% overhead: 1.86 PB * 1.2 ≈ 2.23 PB, rounded to 2.4 PB.