HA architecture

Question 1

What are the 3 types of load balancers?

Answer 1

1) Application –> layer 7 aware > intelligent routing decisions
2) Network –> Extreme performance and static IP
3) Classic –> low cost no intelligent routing

Question 2

What is a 504 error?

Answer 2

Gateway has timed out… this means that the application is not responding within the idle timeout period.

Question 3

How do you troubleshoot a 504 error?

Answer 3

There is an issue with the webserver/database.. Has it failed?

Question 4

How would you access the IPv4 address of client attempting to access a web server?

Answer 4

Look for the x-forwarded for header

Can be used to generate location dependent content…

Question 5

Does an ELB check health or EC2 instances?

Answer 5

Yes the ELB will assign in-service or out of service for EC2 instances it is managing

Question 6

Does an ELB have an IP address?

Answer 6

No and ELB will never have an IP address it will have it’s own DNS name

Question 7

What is a sticky session?

Answer 7

A sticky session enables a user to stick to the same EC2 instance. This can be useful if you are storing information locally to that instance

Question 8

What is cross zone load balancing?

Answer 8

This enables you to load balance across multiple AZs

Question 9

What is a path pattern?

Answer 9

A path pattern allows you to direct traffic to different EC2 instances based on their URLs contained in the request