High Availability and Scaling Flashcards
automatically distributes your incoming traffic across multiple targets, such as EC2 instances, containers, and IP addresses, in one or more Availability Zones.
Elastic Load Balancer
First load balancer that is now out of date and not recommended
Classic Load Balancer (CLB)
Load balancer functions at layer 7 of OSI model, Supports HTTP/S/WebSocket
Application Load Balancer (ALB)
Load balancer functions at the fourth layer of the Open Systems Interconnection (OSI) model. It can handle millions of requests per second. Supports TCP, TLS, UDP
Network Load Balancer (NLB)
Each ELB is configured with an A record which points to the ELB nodes placed across the chosen AZs.
True
ELB Nodes with public IPs AND private IPs
Internet-Facing
ELB Nodes with private IP
Internal-Facing
Controls what protocols and ports will be accepted by the ELB nodes
Listeners
Can an internet-facing ELB connect to both public and private EC2 instances?
Yes
Suggested size by AWS of IP’s for ELBs in order for scale
/27 or larger
Ability to distribute or load balance across all instances in all AZ
Cross-Zone Load Balancing
Will nodes scale automatically if the load increases?
Yes
Are CLB capable of scaling?
No
ALB must have SSL certifications installed if HTTPS is used
True
Are ALB slower than NLB?
Yes
Direct the connections which arrive at a listener in an ALB
Rules
Forwarding encrypted connections without terminating them requires Network Load balancer
True
Can you detailed health checking with a network load balancer?
No
Can NLB have static IPs for whitelisting?
Yes
Can NLB forward TCP to instances with unbroken encryption
Yes
NLB are used with privatelink to provide services to other VPCs
True
Specifies instance configuration information that can be used to easily provision instances in the same configuration
Launch Templates
Used for automatic scaling and self-healing for Ec2 using launch templates/configurations
Auto Scaling Groups
Keeps running instances at the desired capacity by provisioning or termination instances
Auto Scaling Groups
Updates the capacity based on certain criteria/metrics
Scaling Policies
Manually adjust desired capacity
Manual Scaling
Time based scaling used for known periods of usage
Scheduled Scaling
Scale out or in based on a metric reaching an alarm state (ex. cpu usage, i/o)
Simple Scaling
Scaling similar to Simple scaling but the adjustments vary based on the size of the alarm breach, add more control of scaling
Stepped Scaling
Scaling where you set a target value that represents the ideal average utilization or throughput level for your application and the scaling group adds or removes resources to maintain the desired level
Target Tracking
How long to wait on a scaling action before performing another (default 300 seconds)
Cooldown period
Are auto scaling groups free?
Yes only charged for the resources
Are scaling policies required when creating an Auto Scaling Group
No
Create solutions that are aware of events in the Auto Scaling instance lifecycle, and then perform a custom action on instances when the corresponding event occurs
ASG Lifecycle Hooks
Used ensure that your bootstrap scripts have completed successfully and the applications on the instances are ready to accept traffic
ASG Lifecycle Hooks
uses the results of the Amazon EC2 instance status checks and system status checks to determine the health status of an instance
EC2 Health Check
Checks whether the load balancer reports the instance as healthy, confirming whether the instance is available to handle requests
ELB Health Check
health checks by using a combination of custom health checks, Amazon EC2 status checks, and Elastic Load Balancing health checks, if enabled
Custom Health Check
Delay before starting Health Checks (default 300 seconds)
Grace Period
SSL load balancer sits on the edge and grabs all incoming HTTPS traffic. After decryption, the balancer encrypts again and passes it to the server. Every EC2 instance on the backend needs to perform cryptographic operations
SSL Bridging
Network Load Balancer just passes the connection to one of the backend instances, performs no encryption or decryption
SSL Passthrough
Listener configured for HTTPS, ELB needs an SSL certificate for decryption but doesn’t encrypt data passed to the EC2 instances
SSL Offload
Feature to enable the load balancer to bind a user’s session to a specific target. This ensures that all requests from the user during the session are sent to the same target.
Session Stickiness
Used for running and scaling 3rd party appliances and provide network security at scale
Gateway Load Balancer
