ELB & AGS

Question 1

ELB vs ASG

Answer 1

“ELB - distributes the traffic load across available target groups.
ASG - increases or decreases the number of available instances in a group as per the scaling policy.”

Question 2

On ASG what is the launch configuration?

Answer 2

The template used to launch EC2 instances such as AMI, type, key pair, etc

Question 3

When can you modify a launch configuration?

Answer 3

only upon creating it. You can use an existing launch configuration as the basis for a new launch configuration.

Question 4

What are the default metric types for an ASG?

Answer 4

"Application load balancer request count per target
Average CPU Utilization
Average Network in (and out)
Disk reads in (and out)
Disk read operations (and writes)"

Question 5

When does an unhealthy EC2 get spun down and replaced?

Answer 5

After the ELB health check completes and the health check grace period expires

Question 6

What is the ASG default termination policy?

Answer 6

“Most EC2s with at least one that is not protected
> tie looks for the oldest launch configuration
> tie goes to the next closest billing hour
> tie goes to random between these”

Question 7

What are the target health status’s?

Answer 7

“initial - load balancer is regerstering the target or performing initinal health check
healthy - target is healthy
unhealthy - target did not respond to a health check or failed one
unused - target is not registered with a target group, the group is not used ina listener rule of target in AZ not enabled for ELB
draining - target is deregistered and connection draining in progress”

Question 8

What can cause unhealthy status?

Answer 8

"a security group does not allow traffic
a NACL does not allow traffic
the ping path does not exist
the connection times out
the target did not return a successful response code"

Question 9

What is the application load balancer feature?

Answer 9

“ELB feature
Allows developer to configure and route incoming end-user traffic to applications based in the AWS public cloud, pushed across multiple targets in multiple AZs
Cross-zone load balancing is always enabled”

Question 10

What is the cross-zone load balancing feature?

Answer 10

Allows work loads to be balanced across multiple AZs via nodes that are established in each AZ

Question 11

What monitoring features can you use with ELB?

Answer 11

“CloudWatch metrics
Access Logs
Request tracking
CloudTrail Logs”

Question 12

With what identifier do you register a target with an ELB?

Answer 12

“instance - identified by instance ID(different than the ARN)
ip - specified by the IP address of the resource”

Question 13

ELB vs ALB

Answer 13

“ELB - routes to a particular pool of homogeneous servers

ALB - routes to unique servers based on the content of the request”

Question 14

Auto scaling groups default wait period?

Answer 14

adding lifecycle hooks to an auto scaling group puts the instance into a weight State before termination. during this way to State you can perform custom activities the default wait period is 1 hour.

Question 15

what is an auto scaling group cooldown timer

Answer 15

a designated time so the scaling activity may be able to fully take effect and finish its process

Question 16

keywords for ASG scaling policies

Answer 16

“Target - alarm event
step - logic
scheduled scale - schedule”

Question 17

Design protocol for availability in a natural disaster situation

Answer 17

“Route to other regions if one goes out

it is not enough to backup data within the same region”

Question 18

What happens when to policies are executed simultaneously?

Answer 18

“Auto scaling follows the policy with the greater impact

if one creates 2 instances and one creates 4, it will implement the policy that creates 4 instances”