System Design Fundamentals | Pt 4 | Load Balancer

Welcome to Software Interview Prep! Our channel is dedicated to helping software engineers prepare for coding interviews and land their dream jobs. We provide expert tips and insights on everything from data structures and algorithms to system design and behavioral questions. Whether you’re just starting out in your coding career or you’re a seasoned pro looking to sharpen your skills, our videos will help you ace your next coding interview. Join our community of aspiring engineers and let’s conquer the tech interview together!

————————————————————————————————————–

A load balancer is a device or software component that distributes incoming network traffic across multiple servers or resources, with the aim of improving reliability, efficiency, and scalability of the system.

The load balancer acts as an intermediary between the client and the servers, receiving incoming requests and then forwarding them to one of several servers that are capable of handling the request. This allows the workload to be evenly distributed across multiple servers, rather than being handled by a single server, which can lead to overload and poor performance.

Load balancers can be implemented at various layers of the networking stack, including the application layer, transport layer, and network layer. Application layer load balancers are typically used for web applications and can route traffic based on factors such as URL, cookie, or header content. Transport layer load balancers operate at the TCP or UDP layer and can balance traffic based on IP address, port number, or protocol. Network layer load balancers operate at the IP layer and can route traffic based on network addresses and routing tables.

Load balancers can provide several benefits, including increased availability, scalability, and performance of the system. They can also help distribute traffic evenly across multiple servers, which can prevent server overload and improve the user experience. Load balancers can also provide additional features such as SSL termination, content caching, and security features like DDoS protection and firewalling.

Overall, load balancers are an essential component of many high-traffic systems, and are commonly used in web applications, cloud computing, and other distributed systems.

——————————————————————————————————–
Load balancers use various algorithms to distribute incoming traffic across multiple servers or resources. The choice of algorithm depends on the specific needs and requirements of the system, such as the type of traffic being handled, the number of servers, and the desired level of performance.

Here are some common load balancing algorithms:

1. Round-robin: This algorithm distributes traffic evenly across a group of servers in a cyclic manner, with each server receiving an equal number of requests in turn.

2. Least connections: This algorithm directs traffic to the server with the fewest active connections, which helps ensure that the workload is evenly distributed across the servers.

3. IP hash: This algorithm uses the client’s IP address to determine which server to send the request to. This ensures that requests from the same IP address are always directed to the same server, which can help maintain session state and improve cache performance.

4. Weighted round-robin: This algorithm assigns a weight to each server in the group, with higher-weighted servers receiving a greater proportion of the traffic. This can be useful when some servers have more resources or processing power than others.

5. Least response time: This algorithm directs traffic to the server with the lowest response time, which can help ensure that requests are processed quickly and efficiently.

6. Random: This algorithm selects a server at random from the group, which can be useful in some scenarios where a simple load balancing strategy is sufficient.

There are many other load balancing algorithms, and some load balancers support custom algorithms that can be tailored to specific requirements. The choice of algorithm depends on the specific needs of the system and the desired level of performance and scalability.