EC2 - SAA Level Flashcards
What is a public IP? How does it differ from a private IP?
An IP that is accessible over the internet. Private IPs are not.
What is an elastic IP?
A fixed public IP for your instance that is accessible over the internet.
How many instances can be assigned an elastic IP at once?
1
What are the 3 types of EC2 placement groups?
Cluster, spread and partition
Why might you use an EC2 placement group?
To have greater control over where and how your instances are deployed in the AWS infrastructure
What is a cluster placement group?
Single low latency group in a single AZ. Fast but risky
What is a spread placement group? What type of applications should use this type of placement group?
Spreads across underlying hardware. Deployment is over multiple AZs, with max of 7 instances per AZ per group. For critical applications.
What is a partition placement group?
Spreads instances across many different racks of hardware (partitions). Can span multiple AZs in the same region. Up to 100s of instances in each group.
What is an ENI? What does ENI stand for? What are the core components of an ENI?
A virtual network card.
Elastic Network Interface.
Has 1 primary private IPv4, with 1 or more secondary, each with their own elastic IP. Also has one public IPv4 and 1 MAC address.
What are ENIs used for?
To move IP addresses around with deployed EC2 instances for failover purposes
What is hibernating an EC2 instance? What benefit does this have?
When you hibernate an EC2 instance, it’s RAM state is preserved, which results in a much faster boot time.
Extra: An instance cannot be hibernated for more than 60 days.
What 3 characteristics must be satisfied for an EBS volume to be used for EC2 hibernation?
It must be encrypted, not an instance store, and be large.
