Sticky sessions in HLD - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are sticky sessions in load balancing?

Sticky sessions ensure that a user's requests are always sent to the same server during a session, maintaining session state on that server.

beginner

Why are sticky sessions used in web applications?

They are used to keep user session data consistent by routing all requests from the same user to the same server, avoiding session data loss.

intermediate

Name two common methods to implement sticky sessions.

1. Using cookies to track the server assigned to a user.<br>2. Using IP address affinity to route requests.

intermediate

What is a major drawback of sticky sessions?

They can cause uneven load distribution because some servers may get more users than others, leading to potential performance issues.

advanced

How can sticky sessions affect scalability?

Sticky sessions can limit scalability since users are tied to specific servers, making it harder to distribute load evenly and add or remove servers seamlessly.

What does a sticky session ensure in a load balanced system?

A User requests are encrypted end-to-end

B User requests are distributed randomly

C User requests are sent to the least busy server

D User requests go to the same server during a session

Sticky sessions route all requests from the same user to the same server to maintain session state.

Which method is commonly used to implement sticky sessions?

A Using cookies to track server assignment

B Encrypting user data

C Random server selection

D Caching static content

Cookies can store information about which server a user is assigned to, enabling sticky sessions.

What is a potential problem caused by sticky sessions?

A Increased network latency

B Uneven load distribution across servers

C Loss of user data

D Data encryption failure

Sticky sessions can cause some servers to handle more users, leading to uneven load.

Sticky sessions can limit scalability because:

A They require more bandwidth

B They encrypt data too much

C Users are tied to specific servers

D They use random server selection

Tying users to specific servers makes it harder to balance load and scale horizontally.

Which of these is NOT a way to implement sticky sessions?

A Random load balancing

B Using cookies

C IP address affinity

D Session tokens

Random load balancing does not maintain session affinity, so it is not a sticky session method.

Explain what sticky sessions are and why they are used in load balanced systems.

Think about how a website remembers you during your visit.

Describe the advantages and disadvantages of using sticky sessions.

Consider both user experience and system performance.