Web Hosting Flashcards
What is the difference between EBS and EC2 instance store?
EBS is separate from EC2 instance making it slower but more resilient and reliable. Max 256k IOPS
EC2 instance stores is on the instance, it is faster, but less resilient. It will disappear if the EC2 goes down.
Regarding Instance tenancy, if there is a discrepancy between launch config and VPC settings, what takes priority.
If either the launch config or VPC have dedicated tenancy enabled, the instance will be dedicated tenancy. Otherwise, the instance will be shared tenancy.
When an autoscaling group rebalances instances across AZ’s, does it terminate instances before or after spinning up the new instances?
EC2 autoscaling groups will spin up instances before terminating instances to prioritize uptime over cost.
What is a canary deployment?
Canary deployments are when traffic is shifted in increments with configurable percentage-based routing.
Works with ECS task sets and Versioned lambda functions.
For G2 Volumes, what is the relationship between IOPS and GB?
3 IOPS / GB, with a min of 100 IOPS and max of 16,000 IOPS
When should you use round robin vs least outstanding requests routing algorithms on an ALB?
Round robin should be used for similar targets / similar processing per request.
least outstanding requests should be used for variable targets or processing time per request.
What is EFA?
AWS Elastic Fiber Adapter is a specialized network interface that increases network performance on an EC2. It is used for HPC (High performance computing)
What are the available routing algorithms for ALB?
Round Robin
Least Outstanding Requests
Weighted Random
Can a WAF be put directly in front of an ASG?
No. It must be put in front of a load balancer, CloudFront distribution, API Gateway, or AWS AppSync.
What is the difference between Redis and Memcached?
Redis is generally more reliable, as it allows for replication of the primary cluster.
Memcached is a simpler and easier to configure solution.
What is FSx for Lustre?
AWS Managed Lustre File system.
It essentially works as EFS but for HPC (High Performance Computing)
What is AWS Data Lifecycle Manager (DLM)
Service that allows for automated backups of EBS and EBS-backed AMIs.
Combined with EventBridge, it is a complete backup solution for EC2 instances and EBS volumes
What service should be added to an application to provide DDoS protection?
AWS Shield
What are the RPO / RTO of the following DR strategies
Backup / Restore
Pilot Light
Warm Standby
Multisite active/active
Backup / Restore - hours
Pilot Light - 10s of minutes
Warm Standby - minutes
Multisite active/active - near real time
Regarding DR, what is the difference between pilot light and warm standby
Pilot light has all the services ready to go, but not running. It will take minutes for the services in a pilot light environment to spin up. It is cheaper, but slower than Warm Standby. Warm standby is when a mini version of the application is available in a different region. More expensive, but faster than pilot light
