Deployment & Provisioning Flashcards
InstanceLimitExceeded error
You have reached the limit on the number of instances you can launch in a region.
- 20 by default
InsufficientInstanceCapacity error
AWS does not currently have enough available On-Demand capacity to service your request.
- Wait a few minutes and try again - Request fewer instances - Select a different instance type - Purchase Reserved Instances instead - Submit a new request without specifying the AZ
What happens when you hit the IOPS limit of your volume? How to fix it?
App becomes to slow down and I/O request starts queuing
- gp2: increase the size of your volume (only if volume is < 5.2TB)
- if you have already reached 16,000 IOPS, chage storage class to Provisioned IOPS
Bastion Host
It’s a host located in a Public subnet
- Allows you to connect to your EC2 instances using SSH or RDP.
- Used to securely connect to instances in a Private Subnet, without exposing them to the internet.
- Does not enable outgoing requests, internet access for your instances in the private subnet.
Application Load Balancers
Layer 7
- Inspect packets
- Make routing or routing decisions based on the contents of the network packet.
- acloudguru/sales → goes to one server
- acloudguru/marketing → goes to another server.
- It can read HTTP, HTTPS headers.
Network Load Balancers
- Layer 4
- Load balancing TCP traffic
- Millions of requests per second, while maintaining ultra-low latencies.
Classic Load Balancers
Layer 4 and 7
- X-Forwarded-For, which simply allows you to determine the originating IP address for the device which sent the request.
- Allows Sticky sessions: simply binds a user’s session to a specific instance.
When should you Pre-Warm your Load Balancers?
Needed when there will be a crazy increase in your traffic
- Contact AWS and request them Pre-Warm ELB.
- It will configure the ELB to the appropriate level of capacity based on the traffic you expect.
What does AWS need to know in order to Pre-warm your load balancers? (3 things)
Start and end dates
Expected request rate per second
Total size of a typical request
Which ELB type should you use if there is a need for static IP addresses?
NLB
- It attaches 1 static ip address per subnet
400 ELB error
Bad or malformed request
- e.g. Request header malformed. - doesn't conform with HTTP or HTTPS standard.
401 ELB error
Unauthorized - user access denied.
- The user trying to request the web page, they don’t have access to the web page or the website that they’re trying to access.
403 ELB error
Forbidden
- Request is blocked by WAF access control list
460 ELB error
Client closed connection before the load balancer could respond.
- client timeout period may be too short. - it doesn't give the LB sufficient time to actually respond to your request
463 ELB error
LB has received an X-Forwarded-For request header, with more than 30 IP addresses.
- X-Forwarded-For request header allows you to identify the IP address of the originating requester. - Limit is 30 IPs per request - More than 30 you get a 463 error message.
