DNS, Elastic Load Balancing, and Auto Scaling Flashcards
True or False?
Domain Name Service (DNS) is a way to resolve IP addresses of servers internally and on the internet
TRUE
Domain Name Service (DNS)
- Way to resolve IP address of servers internally and on the internet
- Domain name is more user friendly than an IP address (ex. Mycompany.local)
- Computer connects to DNS asking for the IP address for ‘Mycompany.local’ and returns that info back so computer can connect
What is the name of the Amazon intelligent Domain Name Service (DNS)?
Amazon CloudFront
Amazon Inspector
Amazon CloudFormation
Amazon Route 53
Amazon Route 53
-The AWS intelligent Domain Name Service (DNS)
Performs three main functions
- Domain registration
- —>Route 53 allows you to register domain names (xxx.net, xxx.com, xxx.org) - Domain Name Service (DNS)
- —>Route 53 translates name to IP addresses using a global network of authoritative DNS servers - Health Checking
- —>Route 53 sends automated requests to your application to verify that it’s reachable, available and functional
Amazon Route 53 Routing policies:
Amazon Route 53 Routing policies
Simple:
—->-IP address associated with name
Failover:
—->If primary is down, route to secondary
Geolocation:
—->-Route based on geographic location of request
Geoproximity:
—->Route to close region within geo area
Latency:
—->Use lowest latency route to resources
Multivalue answer:
—->Returns several IP Addresses
Weighted:
—->Relative weights (60%/40%)
Represents a set of records belonging to a domain (ex. SF.com, dctlabs.com):
Root User
EBS Volume
Hosted Zone
DynamoDB
Hosted Zone
-Represents a set of records belonging to a domain (ex. Sf.com, dctlabs.com)
A level of automation of how you send traffic to your resources:
Hosted Flow
Traffic Flow
Red light Green light
Amazon Gateway
Traffic Flow
-Another level of automation of how you send traffic to your resources
Scaling Up (Vertical scaling)
VS
Scaling Out (horizontal scaling)Scaling Up (vertical scaling) -Add more HARDWARE (memory, storage space) to a single instance
Disadvantage:
- —>If that instance fails everything fails
- —>Limit (ceiling) to how many resources you can assign)
Scaling Out (horizontal scaling) -Add more INSTANCES
Advantage:
- —>If one instance fails other instances can take over
- —>Almost unlimited capacity
What service automates scaling of EC2 instances horizontally (scaling out) by launching and terminating instances based on demand?
Amazon Redshift
Amazon EC2 Auto Scaling
Amazon CloudFront
Amazon EUR
Amazon EC2 Auto Scaling
- Automates scaling of EC2 instances horizontally (scaling out)
- Launches and terminates instances based on demand
- Helps to ensure you have correct # of EC2 instances available to handle the application load
- Provides ELASTICITY and SCALABILITYy
- You create collections of EC2 instances, called an Auto Scaling Group (ASG)
- Responds to EC2 STATUS CHECKS and CloudWatch metrics
- —>Checks the health and performance of your instances
-Can scale based on demand (performance) or on a schedule
Amazon EC2 Auto Scaling Policies
Scaling policies define how to respond to changes in demand
Target tracking
—->Attempts to keep the group at or close to the metric (ex. 80% CPU)
Simple scaling
—->Adjust group size based on a metric (if go over a threshold add an instance)
Step scaling
- —>Adjust group size based on a metric
- —>Adjustments vary based on the size of the alarm breach (adjusts to add one instance or step up further to more instances)
- Scheduled scaling
- —>Adjust the group size at a specific time
Automatically distributes incoming application traffic across multiple targets, such as Amazon EC2 instances, containers, and IP addresses. Distributes connections to multiple back-end instances which makes your application fault tolerant:
Amazon Elastic Block Storage (EBS) Volume
Amazon Elasticache
Amazon Elastic Load Balancing (ELB)
Amazon CloudWatch
Amazon Elastic Load Balancing (ELB)
Automatically distributes incoming application traffic across multiple targets
—–>(such as Amazon EC2 instances, containers, and IP addresses
Distributes connections to multiple back-end instances which makes your application fault tolerant
You should couple this w/ Auto Scaling to ensure the right amount of back-end instances are available
Can handle the varying load of your application traffic in a single AZ or across multiple AZ’s
—->(but NOT across Regions - use Amazon Route 53 for that)
Features high availability, automatic scaling, and robust security necessary to make your applications fault tolerant
Provides redundancy (multiple hardware (HDD, Network Card, etc) that allow the system to continue to operate
Fault Tolerance
Fault Tolerance
- Ability to recover if something fails
- Provides redundancy (multiple hardware (HDD, Network Card, etc) that allow the system to continue to operate
Types of amazon Elastic Load Balancing (ELB)
- Application Load Balancer (ALB)
- Network Load Balancer (NLB)
Types of amazon Elastic Load Balancing (ELB)
Application Load Balancer (ALB)-
- —>Layer 7 load balancer that routes connections based on the content of the request (domain name)
- —>Supports advanced routing
- —>Most commonly used today
Network Load Balancer (NLB)-
- —>Layer 4 load balancer that routes connections based on IP protocol data
- —>Ultra high performance, low latency and TLS offloading at scale
- Classic Load Balancer (old generation) and Gateway Load Balancer (used in front of virtual appliances such as firewalls, IDS/IPS, and deep packet inspection systems)
- These probably won’t be on exam but good to know that there are other types of Load Balancer
