AWS Certified Solutions Architect - Associate: key terms

Flashcards for this exam AWS Certified Solutions Architect - Associate guide

• 7 Rs of Cloud MigrationSeven migration strategies: retire, retain, rehost, relocate, repurchase, replatform and refactor.Foundational
• Amazon API GatewayAWS fully managed service to create, publish, secure and monitor REST, HTTP and WebSocket APIs.Intermediate
• Amazon AthenaServerless interactive query service that runs SQL directly on data in Amazon S3, billed per data scanned.Foundational
• Amazon AuroraAWS cloud-native relational database compatible with MySQL and PostgreSQL, with distributed, self-healing storage.Intermediate
• Amazon CloudFrontAWS content delivery network that caches and delivers content from edge locations worldwide with low latency.Foundational
• Amazon CloudWatchAWS monitoring and observability service for metrics, logs, alarms, dashboards and events.Foundational
• Amazon CognitoAWS service providing customer identity: user sign-up/sign-in (user pools) and temporary AWS credentials for app users (identity pools).Intermediate
• Amazon Data FirehoseA managed service (formerly Kinesis Data Firehose) that buffers and delivers streaming data to S3, Redshift, OpenSearch, Snowflake and more.Intermediate
• Amazon DocumentDBAWS managed document database with MongoDB API compatibility.Intermediate
• Amazon DynamoDBAWS fully managed serverless NoSQL key-value and document database delivering single-digit millisecond performance at any scale.Foundational
• Amazon EC2 Auto ScalingAWS service that automatically adjusts the number of EC2 instances in an Auto Scaling group to maintain availability and match demand.Foundational
• Amazon Elastic Block Store (EBS)AWS block storage volumes that attach to EC2 instances and persist independently of instance life.Foundational
• Amazon Elastic Compute Cloud (EC2)AWS IaaS service providing resizable virtual servers (instances) billed per second or hour.Foundational
• Amazon Elastic File System (EFS)AWS fully managed, elastic NFS file system for Linux workloads that can be mounted by many instances across AZs.Foundational
• Amazon ElastiCacheAWS managed in-memory caching service compatible with Valkey, Redis OSS and Memcached.Intermediate
• Amazon EventBridgeAWS serverless event bus that routes events from AWS services, SaaS apps and custom sources to targets using rules.Intermediate
• Amazon FSxAWS family of managed file systems: FSx for Windows File Server, Lustre, NetApp ONTAP and OpenZFS.Intermediate
• Amazon GuardDutyAWS intelligent threat detection service analyzing CloudTrail, VPC Flow Logs and DNS logs to find malicious activity.Intermediate
• Amazon InspectorAWS automated vulnerability management service that scans EC2 instances, container images and Lambda functions.Intermediate
• Amazon Kinesis Data Streams (KDS)A managed AWS service for real-time streaming data, with shards that store ordered records for custom consumers to replay.Intermediate
• Amazon Machine Image (AMI)Template containing the OS, software and configuration used to launch EC2 instances.Foundational
• Amazon MacieAWS data security service that uses machine learning and pattern matching to discover sensitive data such as PII in Amazon S3.Intermediate
• Amazon NeptuneAWS fully managed graph database supporting property graph (Gremlin, openCypher) and RDF (SPARQL) models.Intermediate
• Amazon RDS ProxyManaged database proxy that pools and shares connections to RDS and Aurora, improving scalability and failover resilience.Advanced
• Amazon RedshiftAWS fully managed, petabyte-scale columnar data warehouse for analytics using SQL.Foundational
• Amazon Relational Database Service (RDS)AWS managed relational database service for MySQL, PostgreSQL, MariaDB, Oracle, SQL Server and Db2.Foundational
• Amazon Route 53AWS highly available DNS service providing domain registration, DNS routing and health checking.Foundational
• Amazon S3 GlacierFamily of low-cost S3 archive storage classes: Glacier Instant Retrieval, Glacier Flexible Retrieval and Glacier Deep Archive.Foundational
• Amazon Simple Notification Service (SNS)AWS managed pub/sub messaging service that pushes messages from topics to many subscribers.Foundational
• Amazon Simple Queue Service (SQS)AWS fully managed message queue for decoupling application components; offered as Standard and FIFO queues.Foundational
• Amazon Simple Storage Service (S3)AWS object storage service offering virtually unlimited capacity with 99.999999999 percent (11 nines) durability.Foundational
• Application Load Balancer (ALB)AWS layer 7 load balancer that routes HTTP/HTTPS/gRPC traffic based on host, path, headers and query strings.Intermediate
• Aurora Global DatabaseAurora feature replicating a database across AWS regions with typical lag under one second for DR and global reads.Advanced
• Aurora ServerlessOn-demand autoscaling configuration of Amazon Aurora that adjusts database capacity in fine-grained increments.Intermediate
• Availability Zone (AZ)One or more physically separate data centers within a region with independent power, cooling and networking.Foundational
• AWS Application Migration Service (AWS MGN)AWS's primary rehost (lift-and-shift) service that continuously replicates servers to AWS and launches them with minimal cutover downtime.Intermediate
• AWS BackupCentralized AWS service for policy-based backup of EC2, EBS, RDS, DynamoDB, EFS, FSx, S3 and more.Intermediate
• AWS BatchFully managed AWS service for running batch computing jobs at any scale on EC2, Spot or Fargate.Intermediate
• AWS BudgetsAWS service that sets custom cost, usage, reservation or Savings Plans budgets and alerts or acts when thresholds are exceeded.Foundational
• AWS Certificate Manager (ACM)AWS service that provisions, manages and automatically renews SSL/TLS certificates for AWS integrated services.Intermediate
• AWS CloudFormationAWS's native infrastructure as code service that provisions resources from JSON or YAML templates as stacks.Foundational
• AWS CloudHSMAWS service providing dedicated, single-tenant hardware security modules in your VPC under your exclusive control.Advanced
• AWS CloudTrailAWS service that records API activity and account events for governance, auditing and security investigation.Foundational
• AWS Compute OptimizerAWS service that uses machine learning on utilization metrics to recommend optimal resource configurations.Intermediate
• AWS ConfigAWS service that records resource configurations and changes over time and evaluates them against rules for compliance.Intermediate
• AWS Control TowerAWS service that sets up and governs a secure multi-account landing zone using AWS Organizations and best-practice controls.Intermediate
• AWS Cost and Usage Report (CUR)The most comprehensive AWS billing dataset, delivered to S3 with line-item detail of usage, pricing and resource IDs.Intermediate
• AWS Cost ExplorerAWS tool for visualizing, analyzing and forecasting cost and usage over time.Foundational
• AWS Database Migration Service (AWS DMS)AWS service that migrates databases to AWS with minimal downtime using full load and ongoing change data capture.Intermediate
• AWS DataSyncOnline data transfer service that automates copying between on-premises storage, other clouds and AWS storage services.Intermediate
• AWS Direct Connect (DX)AWS service providing a dedicated private network connection from on-premises to AWS that bypasses the public internet.Intermediate
• AWS Directory ServiceAWS service offering managed Microsoft Active Directory, AD Connector and Simple AD.Intermediate
• AWS Elastic BeanstalkAWS PaaS that deploys and manages web applications on EC2, load balancers and Auto Scaling from uploaded code.Intermediate
• AWS Elastic Disaster Recovery (DRS)AWS service that continuously replicates servers into a low-cost staging area for fast recovery in AWS.Intermediate
• AWS Firewall ManagerAWS service for centrally configuring and enforcing firewall rules across accounts in an organization.Advanced
• AWS Global AcceleratorAWS networking service providing two static anycast IPs that route users over the AWS backbone to optimal regional endpoints.Intermediate
• AWS GlueA serverless AWS data integration service for discovering, preparing and transforming data with Spark-based ETL jobs.Intermediate
• AWS Glue Data CatalogA managed, Hive-compatible metadata repository of databases, tables and partitions used by Athena, EMR, Redshift Spectrum and Glue.Intermediate
• AWS IAM Identity CenterAWS service (formerly AWS Single Sign-On) that centrally manages workforce access to multiple AWS accounts and applications.Intermediate
• AWS Identity and Access Management (IAM)Global AWS service for controlling authentication and authorization to AWS resources through users, groups, roles and policies.Foundational
• AWS Key Management Service (AWS KMS)AWS managed service for creating and controlling cryptographic keys used to encrypt data across AWS services.Intermediate
• AWS LambdaAWS serverless compute service that runs code in response to events without provisioning servers, billed per request and duration.Foundational
• AWS Local ZonesAWS infrastructure extension placing compute, storage and database services in metro areas close to large user populations.Intermediate
• AWS Network FirewallManaged, stateful, highly available network firewall and intrusion prevention service for VPCs.Advanced
• AWS OrganizationsAWS service for centrally managing multiple AWS accounts with organizational units, consolidated billing and policies.Foundational
• AWS OutpostsFully managed AWS hardware racks or servers installed in a customer's data center to run AWS services on premises.Intermediate
• AWS PrivateLinkAWS technology providing private connectivity to services across VPCs and accounts through interface endpoints, without exposing traffic to the internet.Advanced
• AWS Resource Access Manager (AWS RAM)AWS service for securely sharing resources such as subnets, Transit Gateways and Route 53 Resolver rules across accounts.Advanced
• AWS Schema Conversion Tool (AWS SCT)Tool that converts database schemas and code between engines for heterogeneous migrations.Intermediate
• AWS Secrets ManagerAWS service for storing, retrieving and automatically rotating secrets such as database credentials and API keys.Intermediate
• AWS Security HubAWS service that aggregates and prioritizes security findings and checks posture against standards across accounts.Intermediate
• AWS Security Token Service (AWS STS)AWS web service that issues temporary, limited-privilege credentials for IAM roles and federated users.Intermediate
• AWS ShieldAWS managed DDoS protection: Shield Standard is automatic and free; Shield Advanced adds enhanced protection and response.Foundational
• AWS Snow FamilyRugged AWS physical devices used to transfer data offline to AWS and to run edge compute in disconnected locations.Foundational
• AWS Step FunctionsAWS serverless workflow service that orchestrates Lambda functions and AWS services as visual state machines.Intermediate
• AWS Storage GatewayHybrid storage service connecting on-premises applications to AWS storage through file, volume and tape interfaces.Intermediate
• AWS Systems Manager (SSM)AWS operations hub for managing EC2 and on-premises servers: patching, remote commands, sessions, inventory, parameters and automation.Intermediate
• AWS Systems Manager Parameter StoreSystems Manager capability for hierarchical storage of configuration data and secrets as plaintext or KMS-encrypted SecureString values.Intermediate
• AWS Transfer FamilyManaged service providing SFTP, FTPS, FTP and AS2 endpoints that store files directly in Amazon S3 or EFS.Intermediate
• AWS Transit Gateway (TGW)Regional AWS network transit hub that interconnects VPCs and on-premises networks through a single gateway with transitive routing.Intermediate
• AWS Trusted AdvisorAWS service that checks your account against best practices for cost, performance, security, fault tolerance, service limits and operations.Foundational
• AWS WAFAWS web application firewall that filters HTTP(S) requests to CloudFront, ALB, API Gateway and other services using rules.Intermediate
• AWS WavelengthAWS infrastructure embedded in telecommunications providers' 5G networks for ultra-low-latency mobile applications.Intermediate
• AWS Well-Architected FrameworkAWS guidance for designing and operating reliable, secure, efficient, cost-effective and sustainable cloud workloads across six pillars.Foundational
• AWS Well-Architected ToolFree AWS console tool for reviewing workloads against the Well-Architected Framework pillars and tracking improvement plans.Foundational
• Backup as a Service (BaaS)Cloud service that stores and manages backups offsite on provider infrastructure, often with policy-based retention.Foundational
• Bare Metal InstanceCloud server that gives the customer direct access to physical hardware without a provider hypervisor layer.Intermediate
• Bastion HostHardened server in a public subnet used as a controlled entry point for administrative access to private instances.Foundational
• Cloud Route TableSet of rules in a virtual network that determines where traffic from subnets or gateways is directed.Intermediate
• CloudFront Origin Access Control (OAC)CloudFront feature that restricts access to an S3 origin so content is served only through the distribution.Advanced
• CloudWatch AlarmCloudWatch feature that watches a metric or expression and changes state (OK, ALARM, INSUFFICIENT_DATA) to trigger actions.Intermediate
• CloudWatch LogsCloudWatch capability for collecting, storing, searching and analyzing log data from AWS services, applications and hosts.Intermediate
• Cost Optimization PillarWell-architected pillar focused on delivering business value at the lowest price point by avoiding unnecessary costs.Foundational
• Cross-Account RoleIAM role in one AWS account that principals in another account are trusted to assume, enabling access without sharing credentials.Intermediate
• Dead Letter Queue (DLQ)Queue receiving messages that could not be processed after a maximum number of delivery attempts.Intermediate
• Dedicated HostPhysical server fully allocated to one customer, giving visibility of sockets and cores for license compliance.Intermediate
• Dedicated InstanceAWS EC2 instance that runs on hardware dedicated to a single customer but without host-level placement control.Intermediate
• Disaster Recovery (DR)Policies, tools and procedures for restoring IT systems and data after a disruptive event such as a regional outage or ransomware.Foundational
• Disaster Recovery as a Service (DRaaS)Cloud service that replicates servers and data to a provider and orchestrates failover so workloads can recover after a disaster.Intermediate
• DynamoDB Accelerator (DAX)Fully managed in-memory cache for DynamoDB that delivers microsecond read latency with API compatibility.Intermediate
• DynamoDB Capacity ModesDynamoDB billing options: on-demand (pay per request) or provisioned (set read and write capacity units, optionally auto scaled).Advanced
• DynamoDB Global TablesDynamoDB feature that replicates tables across multiple AWS regions as a multi-active (multi-writer) database.Advanced
• DynamoDB StreamsTime-ordered log of item-level changes in a DynamoDB table, retained for 24 hours and consumable by Lambda.Advanced
• EBS SnapshotPoint-in-time, incremental backup of an EBS volume stored durably by AWS and usable to create new volumes in any AZ.Intermediate
• EBS Volume TypesEBS options: SSD-backed gp3/gp2 and io2/io1, and HDD-backed st1 and sc1, each with different performance and price.Intermediate
• EC2 Instance TypesNamed EC2 configurations of vCPU, memory, storage and networking grouped into families such as general purpose, compute and memory optimized.Intermediate
• EC2 Placement GroupsEC2 feature controlling how instances are placed on underlying hardware: cluster, spread or partition.Advanced
• EC2 User DataScript or cloud-init data passed to an EC2 instance that runs at first boot to bootstrap configuration.Intermediate
• Edge LocationProvider point of presence near end users used to cache content and terminate connections for CDN and DNS services.Foundational
• Egress ChargesFees cloud providers charge for data transferred out of their network to the internet or across regions and zones.Foundational
• Elastic IP Address (EIP)Static public IPv4 address allocated to an AWS account that can be remapped between instances or network interfaces.Foundational
• Elastic Load Balancing (ELB)AWS managed service that distributes incoming traffic across targets in multiple AZs, including ALB, NLB and GWLB.Foundational
• Elastic Network Interface (ENI)Virtual network card in a VPC that can have private and public IPs, security groups and a MAC address, and can move between instances.Intermediate
• Event-Driven Architecture (EDA)Architecture in which components communicate by producing and reacting to events, typically through brokers, enabling loose coupling.Intermediate
• Fan-Out PatternMessaging pattern where one published message is delivered in parallel to multiple independent consumers.Intermediate
• Fault ToleranceAbility of a system to continue operating without interruption when one or more components fail.Intermediate
• Gateway Load Balancer (GWLB)AWS load balancer that transparently inserts fleets of third-party virtual network appliances, such as firewalls, into traffic paths.Advanced
• Government Cloud (GovCloud)Isolated cloud regions built for government agencies and contractors with stringent compliance such as FedRAMP High and ITAR.Intermediate
• Health CheckPeriodic probe a load balancer, DNS service or orchestrator uses to determine whether a target is healthy and should receive traffic.Foundational
• High Availability (HA)Design goal of keeping a system operational and accessible for a high percentage of time by eliminating single points of failure.Foundational
• Horizontal ScalingIncreasing or decreasing capacity by adding or removing instances or nodes; also called scaling out/in.Foundational
• IAM GroupCollection of IAM users that share attached permission policies.Foundational
• IAM PolicyJSON document defining permissions with Effect, Action, Resource and optional Condition elements.Foundational
• IAM Policy Evaluation LogicRules AWS uses to decide a request: explicit deny wins, then an allow is required from all applicable policy types; otherwise implicit deny.Advanced
• IAM RoleAWS identity with permission policies that trusted principals assume to obtain temporary security credentials.Foundational
• IAM UserAWS identity representing a person or application with long-term credentials such as a password or access keys.Foundational
• Instance Metadata Service (IMDS)Link-local endpoint (169.254.169.254) from which an EC2 instance reads its metadata, user data and role credentials.Advanced
• Instance StoreTemporary block storage physically attached to the EC2 host, offering very high I/O but losing data when the instance stops or terminates.Intermediate
• Internet Gateway (IGW)Horizontally scaled, highly available VPC component that enables communication between a VPC and the internet.Foundational
• Lambda@EdgeCloudFront feature that runs Lambda functions at regional edge caches in response to viewer and origin request/response events.Advanced
• Landing ZonePre-configured, secure, scalable multi-account or multi-subscription cloud environment that serves as the foundation for workloads.Intermediate
• Launch TemplateVersioned AWS configuration specifying AMI, instance type, key pair, security groups and other settings used to launch EC2 instances.Intermediate
• Loose CouplingDesign principle where components interact through well-defined interfaces or queues so failure or change in one does not break others.Foundational
• Multi-Region ArchitectureDesign that deploys an application across two or more cloud regions for resilience to regional failure, lower global latency or data residency.Advanced
• Multi-Site Active-ActiveDR and availability strategy where full production capacity runs simultaneously in multiple regions, all serving traffic.Advanced
• NAT GatewayManaged network address translation service that lets private-subnet resources initiate outbound internet connections while blocking inbound ones.Foundational
• Network ACL (NACL)Stateless, subnet-level firewall in AWS VPCs with numbered allow and deny rules evaluated in order.Intermediate
• Network Load Balancer (NLB)AWS layer 4 load balancer for TCP, UDP and TLS traffic offering ultra-low latency and static IP addresses per AZ.Intermediate
• On-Demand Capacity Reservation (ODCR)AWS feature that reserves EC2 capacity in a specific AZ for any duration, without a term commitment.Advanced
• On-Demand InstancesEC2 pricing model paying per second or hour for compute with no long-term commitment.Foundational
• Operational Excellence PillarWell-architected pillar focused on running and monitoring systems and continually improving processes and procedures.Foundational
• Organizational Unit (OU)Container for AWS accounts within AWS Organizations used to group accounts and apply policies hierarchically.Intermediate
• Performance Efficiency PillarWell-architected pillar focused on using computing resources efficiently to meet requirements as demand and technology evolve.Foundational
• Permissions BoundaryAdvanced IAM feature setting the maximum permissions an identity-based policy can grant to a user or role.Advanced
• Pilot LightDR strategy keeping a minimal core of critical systems, such as replicated databases, running in the recovery region, scaled up during disaster.Intermediate
• Provisioned ConcurrencyAWS Lambda feature that keeps a set number of execution environments initialized to respond with consistent low latency.Advanced
• Provisioned IOPS (PIOPS)Storage performance option where a specific number of I/O operations per second is purchased and guaranteed for a volume.Intermediate
• Queue-Based Load LevelingCloud design pattern that places a queue between a task and a service to smooth intermittent heavy loads.Intermediate
• RDS Multi-AZRDS deployment option that maintains a synchronously replicated standby in another AZ with automatic failover.Intermediate
• Read ReplicaAsynchronously replicated, read-only copy of a database used to offload read traffic and support disaster recovery.Intermediate
• Recovery Point Objective (RPO)Maximum acceptable amount of data loss measured in time before a disruption.Foundational
• Recovery Time Objective (RTO)Maximum acceptable time to restore a service after a disruption.Foundational
• RefactorMigration strategy that re-architects an application to use cloud-native features, also called re-architect.Foundational
• RehostMigration strategy that moves applications to the cloud without modification, commonly called lift and shift.Foundational
• Reliability PillarWell-architected pillar focused on workloads performing their intended function correctly and recovering quickly from failure.Foundational
• RelocateMigration strategy that moves workloads to the cloud at the hypervisor level without purchasing new hardware, rewriting or converting VMs.Intermediate
• ReplatformMigration strategy that makes a few cloud optimizations without changing core architecture, sometimes called lift, tinker and shift.Foundational
• RepurchaseMigration strategy that replaces an existing application with a different product, typically a SaaS offering; also called drop and shop.Foundational
• Reserved Instances (RI)AWS billing discount (up to about 72 percent) for committing to a specific instance configuration for 1 or 3 years.Foundational
• Resource-Based PolicyPolicy attached directly to a resource, such as an S3 bucket or KMS key, specifying which principals can access it.Intermediate
• RetainMigration strategy of keeping an application in its current environment for now, also called revisit.Foundational
• RetireMigration strategy of decommissioning applications that are no longer needed rather than moving them.Foundational
• Root UserThe AWS account's original identity, created with the sign-up email, that has unrestricted access to all resources and billing.Foundational
• Route 53 ResolverDNS resolver built into every VPC, with inbound and outbound endpoints for hybrid DNS resolution and DNS Firewall.Advanced
• Route 53 Routing PoliciesRoute 53 options determining how DNS queries are answered: simple, weighted, latency, failover, geolocation, geoproximity, multivalue and IP-based.Intermediate
• S3 Block Public AccessAccount- and bucket-level S3 settings that override policies and ACLs to prevent public access to buckets and objects.Foundational
• S3 Bucket PolicyResource-based JSON policy attached to an S3 bucket controlling which principals can perform which actions on it.Intermediate
• S3 Event NotificationsS3 feature that sends events such as object created or deleted to Lambda, SQS, SNS or EventBridge.Intermediate
• S3 Intelligent-TieringS3 storage class that automatically moves objects between access tiers based on usage, with no retrieval fees.Intermediate
• S3 Lifecycle ConfigurationRules that automatically transition S3 objects to cheaper storage classes or expire them after set periods.Intermediate
• S3 Object LockS3 feature providing write-once-read-many (WORM) protection with retention periods and legal holds.Intermediate
• S3 Presigned URLTime-limited URL signed with a principal's credentials that grants temporary access to a specific S3 object.Intermediate
• S3 ReplicationAutomatic asynchronous copying of S3 objects to another bucket in the same region (SRR) or a different region (CRR).Intermediate
• S3 Storage ClassesAmazon S3 tiers priced by access frequency and availability, from S3 Standard to Glacier Deep Archive.Foundational
• S3 Transfer AccelerationS3 feature that speeds long-distance uploads by routing data through CloudFront edge locations over the AWS backbone.Intermediate
• S3 VersioningBucket setting that keeps multiple versions of each object to protect against accidental overwrites and deletions.Foundational
• Savings PlansAWS flexible pricing model offering discounts in exchange for a commitment to a consistent dollar amount of compute usage per hour for 1 or 3 years.Foundational
• Security Group (SG)Stateful virtual firewall attached to instances or network interfaces that allows specified inbound and outbound traffic.Foundational
• Security PillarWell-architected pillar focused on protecting data, systems and assets through identity, detection, infrastructure and data protection, and incident response.Foundational
• Service Control Policy (SCP)AWS Organizations policy that sets the maximum available permissions for IAM principals in member accounts.Intermediate
• Session ManagerAWS Systems Manager capability providing browser or CLI shell access to instances without open inbound ports, bastions or SSH keys.Intermediate
• Single Point of Failure (SPOF)Component whose failure stops the entire system because no redundant alternative exists.Foundational
• Site-to-Site VPNEncrypted IPsec tunnel over the internet connecting an on-premises network to a cloud virtual network.Foundational
• Spot InstancesSpare EC2 capacity offered at up to 90 percent discount that AWS can reclaim with a two-minute interruption notice.Foundational
• Stateless ApplicationApplication that keeps no client session data on the server, so any instance can handle any request.Intermediate
• Sustainability PillarAWS Well-Architected pillar, added in 2021, focused on minimizing the environmental impact of cloud workloads.Foundational
• Vertical ScalingIncreasing or decreasing capacity by changing the size of an existing resource, such as more CPU or RAM; also called scaling up/down.Foundational
• Virtual Private Cloud (VPC)Logically isolated virtual network in a public cloud where customers define IP ranges, subnets, routing and security controls.Foundational
• VPC EndpointAWS construct for privately connecting a VPC to supported services without an internet gateway, NAT or public IPs.Intermediate
• VPC Flow LogsFeature that captures metadata about IP traffic going to and from network interfaces in a virtual network.Intermediate
• VPC PeeringPrivate networking connection between two virtual networks that routes traffic using private IP addresses.Intermediate
• Warm StandbyDR strategy running a scaled-down but fully functional copy of production in another site, scaled up on failover.Intermediate