What is the difference between Session Affinity and Sticky Session?

The terms "Session Affinity" and "Sticky Session" are often used interchangeably in the context of load balancing, but they can have nuanced differences depending on the implementation and context.

Session Affinity

Session Affinity, also known as "server affinity" or "source IP affinity," is a mechanism where a load balancer directs all requests from a particular user to the same server based on information from a layer below the application layer, such as the client's IP address. This method ensures that a user's requests are consistently handled by the same server, which can be beneficial for maintaining session state and improving user experience. However, it can be less reliable if the user's IP address changes during the session, such as when using mobile networks or proxies[1][5][6].

Sticky Session

Sticky Session, also known as "session persistence," is a method where the load balancer uses application layer information, such as cookies, to ensure that all requests from a user during a session are directed to the same server. This method is more accurate than session affinity because it relies on application-specific data, such as session cookies, to maintain the connection between the user and the server. Sticky sessions are particularly useful for applications that store session data locally on the server, such as user authentication status or shopping cart contents[1][3][4][5].

Key Differences

1. Layer of Operation:

   • Session Affinity: Operates at a lower network layer (e.g., using IP addresses).
   • Sticky Session: Operates at the application layer (e.g., using cookies).

2. Accuracy:

   • Session Affinity: Less accurate due to potent...