Elastic Load Balancer

Question 1

What are the possible target groups for an Application Load Balancer?

Answer 1

• instance - The targets are specified by instance ID.
• ip - The targets are IP addresses.
• lambda - The target is a Lambda function.

Question 2

How the ELB routs the traffic when you specify targets using an instance ID?

Answer 2

Traffic is routed to instances using the primary private IP address specified in the primary network interface for the instance.

Question 3

Why to use an ALB with Lambda?

Answer 3

• Use load balancer rules to route HTTP requests to a function, based on path or header values.
• You will need either an ALB or API Gateway in front of a Lambda function.

Question 4

Can you set a public IP as an ELB target?

Answer 4

You can’t specify publicly routable IP addresses.

Question 5

What are the ALB use cases?

Answer 5

• HTTP/HTTPS
• path based routing
• host base routing
• query string routing

Question 6

What are the NLB use cases?

Answer 6

• TCP, UDP or TLS
• ultra-high performance
• low latency

Question 7

What are the Gateway LB use cases?

Answer 7

• In front of appliances
• Firewalls

Question 8

What are the NLB targets

Answer 8

EC2 instance
IP address

Question 9

What does the HTTP 503: Service unavailable ALB error mean?

Answer 9

The target groups for the load balancer have no registered targets.

Question 10

What does the HTTP 504: Gateway timeout ALB error mean?

Answer 10

The load balancer failed to establish a connection to the target

Question 11

What does the HTTP 502: Bad gateway ALB error mean?

Answer 11

Other communcation errors beteen the ALB and the taget like:

• unreachable host
• malformed http headers (from the target)
• SSL handshake error
• Lambda function errors