10 Features of Application Load Balancer

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1. Supports content-based routing: Using content-based routing, you can use the path or hostname field inside the HTTP header to route traffic. This supports multiple domains using a single load balancer. It routes the path or hostname to a different target group.

2: Support redirect to one domain to another

Application load balancer supports redirection of one domain to another as well as redirection from HTTP to HTTPS. For more info check this doc https://aws.amazon.com/premiumsupport/knowledge-center/elb-redirect-to-another-domain-with-alb/

3: Fixed response: Using Fixed response load balancer can auto respond to HTTP requests based on any criteria supported by content-based routing rules. You can configure HTTP response codes and custom error messages to be returned to the clients. For more check the following doc https://aws.amazon.com/blogs/aws/new-advanced-request-routing-for-aws-application-load-balancers/

4: Slow start: Slow start allows targets to warm up before receiving requests. It prevents new targets from being overwhelmed with a flood of responses. Load balancer linearly increases the number of requests send to the new target group. Especially useful for application that depends on cache warming for optimal performance.

5: X-Forward for header: The X-Forward for header request captures the IP address of your client in your webserver access logs. For more info check this doc https://aws.amazon.com/premiumsupport/knowledge-center/elb-capture-client-ip-addresses/ or https://docs.aws.amazon.com/elasticloadbalancing/latest/application/x-forwarded-headers.html

6: Comes up with Predefined security policies: Application Load Balancer comes up with a pre-defined security policy that helps to negotiate SSL connection between the client and the load balancer. A security policy is a combination of protocols and ciphers.

• Protocols: To ensure data between the client and loadbalancer is secure, the protocol establishes a secure connection between them.
• Cipher uses an encryption algorithm that uses encryption keys to create a coded message.

For more info check the following doc https://docs.aws.amazon.com/elasticloadbalancing/latest/application/create-https-listener.html#describe-ssl-policies

7: Supports Server Name Indication(SNI): SNI allows the application load balancer to host multiple secured applications, each with its own TLS certificates. It’s due to SNI you can bind multiple certificates to the same secure listener to your load balancer. For more info check this doc https://aws.amazon.com/blogs/aws/new-application-load-balancer-sni/

8: Integration with other services WAF: AWS application load balancer is integrated with a Web Application Firewall(WAF) that monitors web requests and protects your applications from any malicious requests at the load balancer level. The request is allowed or blocked based on the rules defined in a web access control list. Cross-site scripting and SQL injection rule protection are already pre-configured to block these common attacks.

9: Support weighted target group: This is new, but one of my favorite features recently added to ALB. Using weighted routing, you can define how much you can route to the different versions of your application. For more info check https://aws.amazon.com/premiumsupport/knowledge-center/elb-make-weighted-target-groups-for-alb/

10: Support for Round Robin and Least outstanding requests algorithm: The application load balancer supports two algorithms depending upon your requirement

• Round robin: Distribute requests equally to the backend target
• Least outstanding request: Send the request to the target with the least outstanding requests

For more info check this doc https://aws.amazon.com/about-aws/whats-new/2019/11/application-load-balancer-now-supports-least-outstanding-requests-algorithm-for-load-balancing-requests/