CtrlS Interview Questions and Answers

NLB and ALB are both AWS load balancers, but NLB operates at the transport layer while ALB operates at the application layer.

• NLB is designed for extreme performance and low latency, making it suitable for TCP and UDP traffic.

• ALB provides advanced routing capabilities and supports HTTP, HTTPS, and WebSocket protocols.

• NLB supports static IP addresses, while ALB uses dynamic IP addresses.

• ALB supports content-based routing...read more

IAM user is an entity that represents a person or application, while IAM role is an entity that represents a set of permissions.

• IAM user is associated with long-term credentials (access key and secret access key) and is used to directly interact with AWS services.

• IAM role does not have long-term credentials and is assumed by trusted entities, such as AWS services or applications running on EC2 instances.

• IAM user has a ...read more

Security groups and NACLs are both used for network security in AWS, but they operate at different levels of the network stack.

• Security groups are stateful and operate at the instance level, controlling inbound and outbound traffic based on port, protocol, and IP addresses.

• NACLs are stateless and operate at the subnet level, controlling traffic based on subnet IP addresses, port ranges, and protocol numbers.

• Security gr...read more

Route 53 is a DNS web service that routes end users to internet applications by translating domain names to IP addresses.

• Routing policies include simple, weighted, latency-based, failover, geolocation, and multivalue answer.

• Simple routing policy sends traffic to a single resource.

• Weighted routing policy distributes traffic based on assigned weights.

• Latency-based routing policy sends traffic to the region with the lowes...read more

Read replica is a copy of the primary database instance in RDS that allows read-only access to the data.

• Read replicas can be used to offload read traffic from the primary database instance.

• They can be created in the same region or in a different region for disaster recovery purposes.

• Read replicas are asynchronous, meaning that changes made to the primary instance may not be immediately reflected in the read replica.

• The...read more

VPC Endpoint in Amazon S3 allows direct access to S3 from within a VPC without going over the internet.

• VPC Endpoint provides a secure and private connection between VPC and S3.

• It eliminates the need for a NAT gateway or VPN connection.

• It improves security by keeping traffic within the AWS network.

• It reduces data transfer costs and improves performance.

• Examples: accessing S3 buckets from EC2 instances in a VPC, using S3

VPC Peering is a networking connection between two VPCs that allows them to communicate using private IP addresses.

• VPC Peering enables inter-VPC communication within the same AWS region.

• It is a secure and low-latency connection.

• Peered VPCs can share resources like EC2 instances, RDS databases, etc.

• Transitive peering is not supported, meaning VPCs cannot be peered through a peered VPC.

• Peering connections can be establis

PHP is a server-side scripting language used for web development. The current version is PHP 8.0.

• PHP stands for Hypertext Preprocessor

• It is an open-source language

• PHP is used for creating dynamic web pages

• PHP 8.0 was released on November 26, 2020

Database connection process in CodeIgniter involves configuring database settings in config file and loading database library.

• Configure database settings in config file

• Load database library

• Establish connection using database configuration

• Use database functions to perform CRUD operations