Top AWS Load Balancer Interview Questions
- What is Elastic Load Balancer (ELB)?
- What are the key features provided by Elastic Load Balancer (ELB)?
- How AWS Elastic Load Balancing Works?
- What are the types of load balancers?
- What is the difference between auto-scaling and ELB?
- What are Load balancing web sockets?
- How can we assign a static IP address to a ELB?
- Difference between Ingress and Load Balancer?
- List the types of techniques that are used by load balancers?
- What is Distributed concurrency system?
- What do you mean by a target group in AWS Load Balancing?
- What is the difference between cluster and load balancing?
- What is a database cluster?
- Explain NLB in AWS?
- What is VPC load balancer?
What is Elastic Load Balancer (ELB)?Elastic Load Balancing (ELB) is a load-balancing service for Amazon Web Services (AWS) deployments. ELB automatically distributes incoming application traffic and scales resources to meet traffic demand.It also helps an IT team adjust capacity according to incoming application and network traffic. Load balancing divides the amount of work that a computer has to do among multiple computers so that users, in general, get served faster. ELB offers enhanced features including:
Detection of unhealthy Elastic Compute Cloud (EC2) instances.
Spreading instances across healthy channels only.
Flexible cipher support.
Centralized management of Secure Sockets Layer (SSL) certificates.
Optional public key authentication.
Support for both IPv4 and IPv6.
What are the key features provided by Elastic Load Balancer (ELB)?
- High availability
- The most well-known service that relies on ELB is Amazon's EC2, as ELB performs a health check to ensure an instance is still running before sending traffic to it. When an instance fails or is unhealthy, ELB routes traffic to the remaining healthy EC2 instances. If all EC2 instances in a particular availability zone are unhealthy, ELB can route traffic to other availability zones until the original instances restore to a healthy state.
- Automatic scaling
- A developer can use AWS' Auto Scaling feature to guarantee he or she has enough EC2 instances running behind an ELB. The developer sets Auto Scaling conditions, and when a condition is met, a new EC2 instance can spin up to meet the desired minimum. A developer can also set a condition to spin up new EC2 instances to reduce latency.
- ELB supports applications within an Amazon Virtual Private Cloud for stronger network security. An IT team can specify whether it wants an internet-facing or internal load balancer. The latter option enables a developer to route traffic through an ELB using private IP addresses. A developer could also route traffic between different tiers of an application by using multiple internet-facing and internal load balancers; this approach allows an IT team to use a security group along with private IP addresses while exposing only the web-facing tier and its public IP addresses.
How AWS Elastic Load Balancing Works?A load balancer accepts incoming traffic from clients and routes requests to its registered targets (such as EC2 instances) in one or more Availability Zones. The load balancer also monitors the health of its registered targets and ensures that it routes traffic only to healthy targets. When the load balancer detects an unhealthy target, it stops routing traffic to that target. It then resumes routing traffic to that target when it detects that the target is healthy again.
A listener is a process that checks for connection requests. It is configured with a protocol and port number for connections from clients to the load balancer. Likewise, it is configured with a protocol and port number for connections from the load balancer to the targets.