Quiz: Design a URL Shortener

5 questionsNo time limitPass: 60%+10 XP on first pass

The classic first system design question, solved step by step: requirements, estimates, API, short-code generation with base62, data model, caching, scaling and trade-offs.

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Question 1
How many different codes do 7 base62 characters give (approximately)?
7 billion62 million3.5 trillion1 trillion
Question 2
Why is a URL shortener considered read-heavy?
URLs are longEach short link is created once but clicked many timesIt stores imagesIt uses SQL
Question 3
Which redirect lets you count every click accurately?
301302200404

Question 4

What does this print?

def to_base62(n):
    a = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    out = ""
    while n:
        n, r = divmod(n, 62)
        out = a[r] + out
    return out or "0"
print(to_base62(62))

6210Z01

Question 5
What's a good way to make click tracking not slow down redirects?
Update the database synchronously before redirectingSend click events to a queue and aggregate them laterDon't redirect at allStore clicks in the browser only