cloud computing

What is DNS?

Domain Name System - translates urls into IP addresses

What is TCP?

Transmission Control Protocol - method of delivering bytes between endpoints

What is TLS?

Transport Layer Security - encrypts data in transit for HTTPS

What is a Gateway?

A router for managing API request traffic (e.g. rate limitations, auth, route req.)

What is Cloud Computing?

A model that provides on-demand network access to a shared pool of configurable computing resources

What are the characteristics of Cloud comp.?

• On-demand self service

• Available on many devices

• Resource sharing between users

• Scalable resources

• Measured service

What does On-Prem mean?

Hosted inside organisation's own facilities

Describe On-Prem apps/services?

• Installed locally

• Device-specific

• Manual local updates

• Local data (can be lost!)

• Limited by owned hardware

• One-time purchase

• Full control

• Predictable performance

Describe Cloud-based apps/services?

• Hosted in remote datacenters

• Any device can access it

• Provider manages updates

• Remote data (easy backups)

• Elastic resources

• Subscription

• Reliant on provider for protection

• Depends on network & demand

What is a datacenter?

Physical facility with servers, storage & network equipment that is used to distribute data

What are the components of a datacenter?

Racks, rows, flooring, power, cooling, cabling

What's the formula for Power Usage Efficiency (PUE)?

Total Facility Energy / IT equipment energy

Describe the meaning of Power Usage Efficiency values

Good: Between 1.2 & 1.5
Bad: > 2.0

When do clouds save cost?

• Demand fluctuates (pay only during peaks)

• Unknown demand (avoids overbuying hardware at peak times)

• Batch processing (more machines for short time = faster results)

What is a cloud service?

Any remotely accessible IT resource

What are the different system types?

• Centralised (one main user)

• Distributed (many independent systems sharing resources)

What is an IT resource?

Any physical or software component

What is an organisational boundary?

Physical limits of resource control

What is a trust boundary?

Logical limit of trusted systems

What is scaling and its types?

Adjusting resource

• Horizontal: adjust same type of resources

• Vertical: upgrade existing capacity

What are the different actors in Cloud Computing?

• Provider

• Consumer

• Service Owner

• Resource Admin

• Cloud Auditor

• Cloud Broker

• Cloud Carrier

What is Virtualisation?

The illusion of making one physical system appear as multiple independent systems

What are examples of virtualisation?

Virtual Machines, VPNs, virtual storage

What are Virtual Machine Managers (VMM)?

Hypervisor software that handle the orchestration of VMs

Describe the types of Virtual Machine Managers (VMM)

• Bare-metal: runs on hardware

• Hosted: runs on top of OS

Name the types of Virtualisation

• Server

• Hardware

• OS

What is Para-Virtualisation?

The guest OS being aware of and communicating with hypervisor

What's Hybrid-Virtualisation?

Combination of full

What is containerisation?

The packaging of code into a container that runs consistently anywhere

What are the qualities of containers?

• Portable

• Lightweight

• Isolated

• Fault-isolated

• Easy Operational Management

What are the components of containerised apps?

• Container Host

• Registry Server

• Container image

• Container Engine/Runtime

• Container Orchestrator

What are some other components of containerised apps?

• Namespace

• Kernel namespace

• Repository

• Tag

• Graph Driver

What are Unikernels?

• Specialised, small, single-purpose machine images

• Includes a small kernel in each deployment

What are sandboxed containers?

Containers with an additional mini VM as a boundary

What is a microVM?

Tiny, single-process VM that is headless / API-driven

What is isolation?

How well workloads are protected from one another on the same system?

What are the strength rankings for containerised apps? (In increasing order)

Containers -> Sandboxed cont. -> microVMs/VMs -> Unikernels

What is multi-cloud computing?

Use of multiple cloud providers in one architecture

What does IaaS refer to?

Infrastructure as a Service

What does PaaS refer to?

Platform as a Service

What does SaaS refer to?

Software as a Service

What does FaaS refer to?

Function as a Service

What do Caas, DBaas, MLaaS, DRaaS and STaaS refer to?

• Container as a Service

• Database as …

• Machine Learning as …

• Disaster Recover as …

• Storage as …

What does XaaS refer to?

"anything" as a Service (any IT resource)

What does Serverless Computing mean?

A model where cloud providers manages all services

What are microservices?

An architecture where a monolith is split into a collection of many independent services

What are Cloud-Native apps?

Apps built specifically for cloud environments using containers, microservices & automation

What is a service mesh?

A network layer that manages communication between microservices

What does a sidecar proxy do?

Network proxy that runs beside each microservice and intercepts all service traffic

What does scalability mean?

ability to handle higher load by adjusting resources

What does resilience mean?

ability to maintain performance despite faults

What does adaptability mean?

ability to adjust behaviour quickly without downtime / code rewrite

What is Cloud Orchestration?

Automated management, coordination & scaling of containers

List the core concepts of the orchestration platform Kubernetes

• Pod

• Worker Node

• Master Node

• Service

• DaemonSet

• Deployment

What are some other components of Kubernetes?

• Clusters

• Labels

• Volumes

• Secrets

• Replica sets/controllers

• Names

What are Spot VMs/Containers?

Use of unused cloud capacity from providers at a lower cost

What's the catch with Spot VMs/Containers?

Can be terminated anytime if needed by others

What does Infrastructure as Code (IaC) mean?

Managing of cloud infrastructure through code

What is the typical workflow of Infrastructure as Code (IaC)?

1. Write code by defining info (YAML/JSON)

2. Store in GIT

3. Plan, Preview & Review

4. Deploy

5. Maintain (update through code)

When does spot instance preemption happen?

When a provider stops your instance mid-execution

How is spot instance preemption handled?

Checkpointing - saving current state as task queues periodically

What does Platform as Code (PaC) do?

• Extends IaaS to PaaS environments

• Defines how apps/platform services are configured, deployed and scaled using code

What are the different layers of a cloud service stack?

(In increasing abstraction & decreasing control order)

• Infrastructure (IaaS, hardware)

• Application (PaaS, CaaS, FaaS)

• Middleware (API, security)

• Data (DBaaS, MLaaS)

• User (SaaS)

What are APIs?

Application programming interfaces (APIs) - lets different software systems talk to each other by sharing data / functions

What are the different types of APIs?

• Public/External

• Partner

• Private/Internal

• Composite

What does REST refer to?

Representational State Transfer

• Stateless, caching, uses HTTP verbs, high flexibility for public APIs

What does SOAP refer to?

Simple Object Access Protocol

• Tightly structured, extensible, XML-based, HTTP verbs, high security for internal/partner APIs

What does RPC refer to?

Remote Procedure Call

• Calls functions on remote server, similar to SOAP, for use with simple APIs

What are webhooks?

Automated messages sent from applications to other applications containing information about an event

What is a workload?

Any task or service that needs computing resources

What are SLAs?

Service Level Agreements

• Contracts between a service provider & a customer

• Defines performance & reliability expectations

What is the difference between a public and private SLA?

Public - fixed for all users
Private - customised for big clients

What do cloud schedulers do?

Assign workloads to resources efficiently to meet SLAs

What are the different scheduling algorithms?

• Bin Packing

• Round Robin

• Priority-Based

• Cost-Aware

• Fair Scheduling

What are CDNs?

Content Delivery Networks

• Groups of servers distributed globally to reduce latency of data

What does CDN do exactly?

• Stores static content at edge locations

• Caches content

• Places content closer to user

• Offers DDoS protection, WAF, SSL termination

What's the typical workflow of CDNs?

1. User Request

2. CDN Request (checks if cached, if it is, step 5)

3. Cloud Response (if not cached, cloud fetches)

4. Content Caching

5. Content Delivery (CDN serves from cache)

What is Cloud Storage?

Data storage that is accessible over a network

What are the different Storage Models?

• Object Storage (metadata

What is a Data Pipeline?

A series of process that move data from source to destination

What are the main steps of a data pipeline?

1. Collection

2. Transformation

3. Delivery

What is a data lake?

Distributed storage system for vast amounts of raw data

What are the main layers of a data lake?

• Ingestion (collect raw data)

• Storage (store using object storage)

• Governance (manage quality, security)

• Consumption (analytics)

What are the differences between Schema-on-Read & Schema-on-Write?

• Schema-on-Read: data stored as is structure applied on read

• Schema-on-Write: structure data before storing