INTRODUCTION
1. _________ computing refers to applications and services that run on a distributed network using virtualized resources.
a) Distributed
b) Cloud
c) Soft
d) Parallel
View Answer
a) Distributed
b) Cloud
c) Soft
d) Parallel
View Answer
Answer:b
Explanation:Cloud Computing applications are accessed by common Internet protocols and networking standards.
Explanation:Cloud Computing applications are accessed by common Internet protocols and networking standards.
2. Point out the wrong statement :
a) The massive scale of cloud computing systems was enabled by the popularization of the Internet
b) Soft computing represents a real paradigm shift in the way in which systems are deployed
c) Cloud computing makes the long-held dream of utility computing possible with a pay-as-you-go, infinitely scalable, universally available system
d) All of the mentioned
View Answer
a) The massive scale of cloud computing systems was enabled by the popularization of the Internet
b) Soft computing represents a real paradigm shift in the way in which systems are deployed
c) Cloud computing makes the long-held dream of utility computing possible with a pay-as-you-go, infinitely scalable, universally available system
d) All of the mentioned
View Answer
Answer:b
Explanation:Cloud Computing is distinguished by the notion that resources are virtual and limitless and that details of the physical systems on which software runs are abstracted from the user.
Explanation:Cloud Computing is distinguished by the notion that resources are virtual and limitless and that details of the physical systems on which software runs are abstracted from the user.
3. ________ as a utility is a dream that dates from the beginning of the computing industry itself.
a) Model
b) Computing
c) Software
d) All of the mentioned
View Answer
a) Model
b) Computing
c) Software
d) All of the mentioned
View Answer
Answer:b
Explanation:Cloud computing takes the technology, services, and applications that are similar to those on the Internet and turns them into a self-service utility.
Explanation:Cloud computing takes the technology, services, and applications that are similar to those on the Internet and turns them into a self-service utility.
4. Which of the following is essential concept related to Cloud ?
a) Reliability
b) Productivity
c) Abstraction
d) All of the mentioned
View Answer
a) Reliability
b) Productivity
c) Abstraction
d) All of the mentioned
View Answer
Answer:c
Explanation:Cloud computing abstracts the details of system implementation from users and developers.
Explanation:Cloud computing abstracts the details of system implementation from users and developers.
5. Point out the wrong statement :
a) All applications benefit from deployment in the cloud
b) With cloud computing, you can start very small and become big very fast
c) Cloud computing is revolutionary, even if the technology it is built on is evolutionary
d) None of the mentioned
View Answer
a) All applications benefit from deployment in the cloud
b) With cloud computing, you can start very small and become big very fast
c) Cloud computing is revolutionary, even if the technology it is built on is evolutionary
d) None of the mentioned
View Answer
Answer:a
Explanation:Issues with latency, transaction control, and in particular security and regulatory compliance are of particular concern.
Explanation:Issues with latency, transaction control, and in particular security and regulatory compliance are of particular concern.
6. Which of the following cloud concept is related to pooling and sharing of resources ?
a) Polymorphism
b) Abstraction
c) Virtualization
d) None of the mentioned
View Answer
a) Polymorphism
b) Abstraction
c) Virtualization
d) None of the mentioned
View Answer
Answer:c
Explanation:Applications run on physical systems that aren’t specified, data is stored in locations that are unknown, administration of systems is outsourced to others, and access by users is ubiquitous.
Explanation:Applications run on physical systems that aren’t specified, data is stored in locations that are unknown, administration of systems is outsourced to others, and access by users is ubiquitous.
7. ________ has many of the characteristics of what is now being called cloud computing.
a) Internet
b) Softwares
c) Web Service
d) All of the mentioned
View Answer
a) Internet
b) Softwares
c) Web Service
d) All of the mentioned
View Answer
Answer:a
Explanation:The Internet offers abstraction, runs using the same set of protocols and standards, and uses the same applications and operating systems.
Explanation:The Internet offers abstraction, runs using the same set of protocols and standards, and uses the same applications and operating systems.
8. Which of the following can be identified as cloud ?
a) Web Applications
b) Intranet
c) Hadoop
d) All of the mentioned
View Answer
a) Web Applications
b) Intranet
c) Hadoop
d) All of the mentioned
View Answer
Answer:c
Explanation:When an intranet becomes large enough that a diagram no longer wishes to differentiate between individual physical systems, the intranet too becomes identified as a cloud.
Explanation:When an intranet becomes large enough that a diagram no longer wishes to differentiate between individual physical systems, the intranet too becomes identified as a cloud.
9. Cloud computing is an abstraction based on the notion of pooling physical resources and presenting them as a ________ resource.
a) real
b) virtual
c) cloud
d) None of the mentioned
View Answer
a) real
b) virtual
c) cloud
d) None of the mentioned
View Answer
Answer:b
Explanation:Cloud Computing is a new model for provisioning resources, for staging applications, and for platform-independent user access to services.
Explanation:Cloud Computing is a new model for provisioning resources, for staging applications, and for platform-independent user access to services.
10. Which of the following is Cloud Platform by Amazon ?
a) Azure
b) AWS
c) Cloudera
d) All of the mentioned
View Answer
a) Azure
b) AWS
c) Cloudera
d) All of the mentioned
View Answer
Answer:c
Explanation:One of the most successful cloud-based businesses is Amazon Web Services, which is an Infrastructure as a Service offering that lets you rent virtual computers on Amazon’s own infrastructure.
Explanation:One of the most successful cloud-based businesses is Amazon Web Services, which is an Infrastructure as a Service offering that lets you rent virtual computers on Amazon’s own infrastructure.
1. ______-sizing is possible when the system load is cyclical or in some cases when there are predictable bursts or spikes in the load.
a) Left
b) Right
c) Top
d) All of the mentioned
View Answer
a) Left
b) Right
c) Top
d) All of the mentioned
View Answer
Answer:b
Explanation:You encounter cyclical loads in many public facing commercial ventures with seasonal demands, when the load is affected by time zones.
Explanation:You encounter cyclical loads in many public facing commercial ventures with seasonal demands, when the load is affected by time zones.
2. Point out the correct statement :
a) A standard machine instance (virtual computer) might cost $0.10 or less an hour
b) A typical storage charge might be $0.10 per GB/month
c) Outsourcing shifts the burden of capital expenditures onto the service provider
d) All of the mentioned
View Answer
a) A standard machine instance (virtual computer) might cost $0.10 or less an hour
b) A typical storage charge might be $0.10 per GB/month
c) Outsourcing shifts the burden of capital expenditures onto the service provider
d) All of the mentioned
View Answer
Answer:d
Explanation:In reality, the major cloud providers provide machine instances in small slices that can be added within five minutes or less.
Explanation:In reality, the major cloud providers provide machine instances in small slices that can be added within five minutes or less.
3. _____ is a financial estimate for the costs of the use of a product or service over its lifetime.
a) TCO
b) TOC
c) COT
d) All of the mentioned
View Answer
a) TCO
b) TOC
c) COT
d) All of the mentioned
View Answer
Answer:a
Explanation:TCO stands for total Cost of Ownership.
Explanation:TCO stands for total Cost of Ownership.
4. The Microsoft ____ Platform ROI wizard provides a quick and dirty analysis of your TCO for a cloud deployment on Windows Azure in an attractive report format.
a) AWS
b) EC2
c) Azure
d) All of the mentioned
View Answer
a) AWS
b) EC2
c) Azure
d) All of the mentioned
View Answer
Answer:c
Explanation:A better metric for enterprises is captured by a Return on Investment or ROI calculation.
Explanation:A better metric for enterprises is captured by a Return on Investment or ROI calculation.
5. Point out the wrong statement :
a) TCO must account for the real costs of items, but frequently they do not
b) A system consumes resources such as space in a datacenter or portion of your site, power, cooling, and management
c) Microsoft maintains an economics page for its Windows Azure Platform
d) None of the mentioned
View Answer
a) TCO must account for the real costs of items, but frequently they do not
b) A system consumes resources such as space in a datacenter or portion of your site, power, cooling, and management
c) Microsoft maintains an economics page for its Windows Azure Platform
d) None of the mentioned
View Answer
Answer:d
Explanation:When you account for monitoring and management of systems, you must account for the burdened cost of an IT employee, the cost of the hardware and software that is used for management, and other hidden costs.
Explanation:When you account for monitoring and management of systems, you must account for the burdened cost of an IT employee, the cost of the hardware and software that is used for management, and other hidden costs.
6. A ________ Level Agreement (SLA) is the contract for performance negotiated between you and a service provider.
a) Service
b) Application
c) Deployment
d) All of the mentioned
View Answer
a) Service
b) Application
c) Deployment
d) All of the mentioned
View Answer
Answer:a
Explanation:In the early days of cloud computing, all SLAs were negotiated between a client and the provider.
Explanation:In the early days of cloud computing, all SLAs were negotiated between a client and the provider.
7. Which of the following is specified parameter of SLA ?
a) Response times
b) Responsibilities of each party
c) Warranties
d) All of the mentioned
View Answer
a) Response times
b) Responsibilities of each party
c) Warranties
d) All of the mentioned
View Answer
Answer:d
Explanation:Some SLAs are enforceable as contracts.
Explanation:Some SLAs are enforceable as contracts.
8. When you purchase shrink-wrapped software, you are using that software based on a licensing agreement called ________
a) EULA
b) EUL
c) ELA
d) All of the mentioned
View Answer
a) EULA
b) EUL
c) ELA
d) All of the mentioned
View Answer
Answer:a
Explanation:EULA stands for End User License Agreement.
Explanation:EULA stands for End User License Agreement.
9. Cloud computing shifts capital expenditures into ________ expenditures.
a) operating
b) service
c) local
d) None of the mentioned
View Answer
a) operating
b) service
c) local
d) None of the mentioned
View Answer
Answer:a
Explanation:Cloud computing changes the nature of the service provider and its relationship to its client.
Explanation:Cloud computing changes the nature of the service provider and its relationship to its client.
10. Which of the following service is used for backing up a licensed computer ?
a) CarbonT
b) Karbonite
c) Carbonite
d) None of the mentioned
View Answer
a) CarbonT
b) Karbonite
c) Carbonite
d) None of the mentioned
View Answer
Answer:c
Explanation:Cloud computing applications rarely use machine licenses when the application is meant to be ubiquitous.
Explanation:Cloud computing applications rarely use machine licenses when the application is meant to be ubiquitous.
CONNECTING TO THE CLOUD
1. Which of the following is one of the property that differentiates cloud computing ?
a) scalability
b) virtualization
c) composability
d) All of the mentioned
View Answer
a) scalability
b) virtualization
c) composability
d) All of the mentioned
View Answer
Answer:c
Explanation:Composability is the ability to build applications from component parts.
Explanation:Composability is the ability to build applications from component parts.
2. Point out the correct statement :
a) Cloud computing is a natural extension of many of the design principles, protocols, plumbing, and systems
b) Platforms are used to create more easy software
c) All SLAs are enforceable as contracts
d) All of the mentioned
View Answer
a) Cloud computing is a natural extension of many of the design principles, protocols, plumbing, and systems
b) Platforms are used to create more easy software
c) All SLAs are enforceable as contracts
d) All of the mentioned
View Answer
Answer:a
Explanation:Cloud computing describes some new capabilities that are architected into an application stack and are responsible for the programmability, scalability, and virtualization of resources.
Explanation:Cloud computing describes some new capabilities that are architected into an application stack and are responsible for the programmability, scalability, and virtualization of resources.
3. A _________ is a cloud computing service that is both hardware and software.
a) service
b) platform
c) model
d) All of the mentioned
View Answer
a) service
b) platform
c) model
d) All of the mentioned
View Answer
Answer:b
Explanation:Virtual appliances are an important example of a platform.
Explanation:Virtual appliances are an important example of a platform.
4. Cloud computing doesn’t require that ________ and software be composable.
a) cloud
b) database
c) hardware
d) All of the mentioned
View Answer
a) cloud
b) database
c) hardware
d) All of the mentioned
View Answer
Answer:c
Explanation:It is a highly desirable characteristic from a developer or user’s standpoint.
Explanation:It is a highly desirable characteristic from a developer or user’s standpoint.
5. Point out the wrong statement :
a) Virtual appliances are becoming a very important standard cloud computing deployment object
b) Cloud computing requires some standard protocols
c) Cloud computing relies on a set of protocols needed to manage interprocess communications
d) None of the mentioned
View Answer
a) Virtual appliances are becoming a very important standard cloud computing deployment object
b) Cloud computing requires some standard protocols
c) Cloud computing relies on a set of protocols needed to manage interprocess communications
d) None of the mentioned
View Answer
Answer:d
Explanation:Many of these protocols are standard Internet protocols.
Explanation:Many of these protocols are standard Internet protocols.
6. The most commonly used set of protocols uses ______ as the messaging format.
a) XML
b) JSON
c) BSON
d) All of the mentioned
View Answer
a) XML
b) JSON
c) BSON
d) All of the mentioned
View Answer
Answer:a
Explanation:Cloud computing builds on the architecture developed for staging large distributed network applications on the Internet.
Explanation:Cloud computing builds on the architecture developed for staging large distributed network applications on the Internet.
7. Which of the following language is used to manage transactions ?
a) WSDL
b) XML
c) SOAP
d) All of the mentioned
View Answer
a) WSDL
b) XML
c) SOAP
d) All of the mentioned
View Answer
Answer:a
Explanation:WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information.
Explanation:WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information.
8. Which of the architectural layer is used as backend in cloud computing ?
a) client
b) cloud
c) soft
d) All of the mentioned
View Answer
a) client
b) cloud
c) soft
d) All of the mentioned
View Answer
Answer:b
Explanation:The cloud creates a system where resources can be pooled and partitioned as needed.
Explanation:The cloud creates a system where resources can be pooled and partitioned as needed.
9. A ________ cloud requires virtualized storage to support the staging and storage of data.
a) soft
b) compute
c) local
d) None of the mentioned
View Answer
a) soft
b) compute
c) local
d) None of the mentioned
View Answer
Answer:b
Explanation:From a user’s perspective, it is important that the resources appear to be infinitely scalable, that the service be measurable, and that the pricing be metered.
Explanation:From a user’s perspective, it is important that the resources appear to be infinitely scalable, that the service be measurable, and that the pricing be metered.
10. A _______ system uses components to assemble services that can be tailored for a specific purpose using standard parts.
a) reliable
b) scalable
c) composable
d) None of the mentioned
View Answer
a) reliable
b) scalable
c) composable
d) None of the mentioned
View Answer
Answer:c
Explanation:Applications built in the cloud often have the property of being built from a collection of components, a feature referred to as composability.
Explanation:Applications built in the cloud often have the property of being built from a collection of components, a feature referred to as composability.
CLOUD MAIL SERVICES
1. Which of the following transport protocol is used for POP3 and IMAP access in Gmail ?
a) TTP
b) TLS
c) HTTP
d) All of the mentioned
View Answer
a) TTP
b) TLS
c) HTTP
d) All of the mentioned
View Answer
Answer:b
Explanation:TLS stands for Transport Layer Security.
Explanation:TLS stands for Transport Layer Security.
2. Point out the wrong statement:
a) Gmail is written to look like an Internet chat utility
b) Gmail tends to perform most of its operations such as archiving on the conversation as a whole
c) When a conversation gets to be 50 messages long, Gmail splits the conversation into a second section
d) All of the mentioned
View Answer
a) Gmail is written to look like an Internet chat utility
b) Gmail tends to perform most of its operations such as archiving on the conversation as a whole
c) When a conversation gets to be 50 messages long, Gmail splits the conversation into a second section
d) All of the mentioned
View Answer
Answer:c
Explanation:When a conversation gets to be 100 messages long, Gmail splits the conversation into a second section.
Explanation:When a conversation gets to be 100 messages long, Gmail splits the conversation into a second section.
3. Which of the following prototypical POP3 Webmail mail retrieval service was established in 1997 ?
a) Gmail
b) Mail2Web
c) Yahoo Mail
d) All of the mentioned
View Answer
a) Gmail
b) Mail2Web
c) Yahoo Mail
d) All of the mentioned
View Answer
Answer:b
Explanation:From the Mail2Web interface, you can read messages, reply, and create new messages.
Explanation:From the Mail2Web interface, you can read messages, reply, and create new messages.
4. Mail2Web also has a mobile e-mail service based on Exchange called __________ Mobile E-mail.
a) Mail2.com
b) Mail2Web.com
c) MailWeb.com
d) All of the mentioned
View Answer
a) Mail2.com
b) Mail2Web.com
c) MailWeb.com
d) All of the mentioned
View Answer
Answer:b
Explanation:Mail2Web.com provides online access to any POP3 account.
Explanation:Mail2Web.com provides online access to any POP3 account.
5. Point out the wrong statement:
a) In Gmail, you cannot construct searches with multiple operators using the Advanced Search feature
b) Google uses an advertiser-driven model to supply its free service to users
c) RSS content can be read in most modern browsers
d) None of the mentioned
View Answer
a) In Gmail, you cannot construct searches with multiple operators using the Advanced Search feature
b) Google uses an advertiser-driven model to supply its free service to users
c) RSS content can be read in most modern browsers
d) None of the mentioned
View Answer
Answer:a
Explanation:In its search function, Google uses the keywords from your search and your search history to match sponsors to you.
Explanation:In its search function, Google uses the keywords from your search and your search history to match sponsors to you.
6. Which of the following is Microsoft’s Webmail offering and with localized versions in 36 languages ?
a) AOL Mail
b) Windows Live Hotmail
c) Yahoo Mail
d) None of the mentioned
View Answer
a) AOL Mail
b) Windows Live Hotmail
c) Yahoo Mail
d) None of the mentioned
View Answer
Answer:b
Explanation:Windows Live Hotmail is one of the central applications in Microsoft Windows Live product portfolio.
Explanation:Windows Live Hotmail is one of the central applications in Microsoft Windows Live product portfolio.
7. Which of the following browser is not supported for Hotmail Service ?
a) Firefox
b) Safari
c) Chrome
d) All of the mentioned
View Answer
a) Firefox
b) Safari
c) Chrome
d) All of the mentioned
View Answer
Answer:b
Explanation:Windows Live Hotmail was created with Ajax technology.
Explanation:Windows Live Hotmail was created with Ajax technology.
8. Which of the following Hotmail feature has ability to set a spam filter directly with your mouse ?
a) 1-Click Filters
b) 2-Click Filters
c) Mail Filers
d) All of the mentioned
View Answer
a) 1-Click Filters
b) 2-Click Filters
c) Mail Filers
d) All of the mentioned
View Answer
Answer:a
Explanation:Hotmail has a strong feature set.
Explanation:Hotmail has a strong feature set.
9. Which of the following adds the ability to synchronize messages, contacts, and calendars on any mobile phone that has ActiveSync ?
a) Exchange ActiveSync
b) Exchange PassiveSync
c) EmailRackspace
d) All of the mentioned
View Answer
a) Exchange ActiveSync
b) Exchange PassiveSync
c) EmailRackspace
d) All of the mentioned
View Answer
Answer:a
Explanation:Hotmail also can be viewed in Microsoft Office Outlook using the Outlook Connector or using Windows Live for Windows Mobile phones on that phone’s operating system.
Explanation:Hotmail also can be viewed in Microsoft Office Outlook using the Outlook Connector or using Windows Live for Windows Mobile phones on that phone’s operating system.
10. Yahoo! added a version of the user interface based on Ajax that looks like a form of _____________
a) Gmail
b) Microsoft Outlook
c) AOL Mail
d) None of the mentioned
View Answer
a) Gmail
b) Microsoft Outlook
c) AOL Mail
d) None of the mentioned
View Answer
Answer:b
Explanation:This Ajax interface is based on the work of Oddpost, which the company acquired in 2004.
Explanation:This Ajax interface is based on the work of Oddpost, which the company acquired in 2004.
CLOUD BACKUP FEATURES
1. If you have a local version of a file, then a version of that file stored in the cloud conforms to all three of the ______ backup rules.
a) 3-2-1
b) One-two-three
c) 1-2-3
d) All of the mentioned
View Answer
a) 3-2-1
b) One-two-three
c) 1-2-3
d) All of the mentioned
View Answer
Answer:c
Explanation:Peter Krogh’s 3-2-1 Rule for data protection is a good one to follow.
Explanation:Peter Krogh’s 3-2-1 Rule for data protection is a good one to follow.
2. Point out the correct statement:
a) Replication creates a copy of the data which is not synchronized
b) An archive removes older information that is no longer operational and saves it for long-term storage
c) Reverse delta backup allows a system to do what is referred to as a bare metal restore
View Answer
a) Replication creates a copy of the data which is not synchronized
b) An archive removes older information that is no longer operational and saves it for long-term storage
c) Reverse delta backup allows a system to do what is referred to as a bare metal restore
View Answer
Answer:b
Explanation:A backup creates a copy of the data whereas an archive removes older information.
Explanation:A backup creates a copy of the data whereas an archive removes older information.
3. Which of the following is first rule according to 3-2-1 Backup Rule by Peter Krogh ?
a) Retain three copies of any file—an original and two backups
b) Files must be on two different media types
c) One copy must be stored offsite
d) All of the mentioned
View Answer
a) Retain three copies of any file—an original and two backups
b) Files must be on two different media types
c) One copy must be stored offsite
d) All of the mentioned
View Answer
Answer:c
Explanation:Files must be on two different media types such as hard drives and optical media to protect against different types of hazards.
Explanation:Files must be on two different media types such as hard drives and optical media to protect against different types of hazards.
4. Which of the following is incorrect feature of cloud storage backup solution ?
a) Logon authentication
b) Low Encryption
c) Fast backup
d) None of the mentioned
View Answer
a) Logon authentication
b) Low Encryption
c) Fast backup
d) None of the mentioned
View Answer
Answer:b
Explanation:High Encryption is provided by Cloud Backup Storage.
Explanation:High Encryption is provided by Cloud Backup Storage.
5. Point out the wrong statement:
a) In a differential backup, the backup software can obtain the up-to-date backup from the last full backup and the last incremental backup alone
b) Incremental backup analyzes the transactions that are in progress
c) A cloud storage system contains a certain built-in latency, so unless the original data set is quiescent, the mirror lags behind the original in concurrency
d) None of the mentioned
View Answer
a) In a differential backup, the backup software can obtain the up-to-date backup from the last full backup and the last incremental backup alone
b) Incremental backup analyzes the transactions that are in progress
c) A cloud storage system contains a certain built-in latency, so unless the original data set is quiescent, the mirror lags behind the original in concurrency
d) None of the mentioned
View Answer
Answer:b
Explanation:An open file backup analyzes the transactions that are in progress.
Explanation:An open file backup analyzes the transactions that are in progress.
6. Which of the following is most important feature of cloud storage listed below ?
a) Logon authentication
b) Bare file
c) Multiplatform support
d) Adequate bandwidth
View Answer
a) Logon authentication
b) Bare file
c) Multiplatform support
d) Adequate bandwidth
View Answer
Answer:a
Explanation:The interactive logon process is the first step in user authentication and authorization.
Explanation:The interactive logon process is the first step in user authentication and authorization.
7. How many bits of encryption is at least required for cloud backup storage solution ?
a) 56
b) 84
c) 128
d) None of the mentioned
View Answer
a) 56
b) 84
c) 128
d) None of the mentioned
View Answer
Answer:c
Explanation:High encryption of data transfers is carried out preferably end-to-end, but at least for the data that is transferred over the Internet.
Explanation:High encryption of data transfers is carried out preferably end-to-end, but at least for the data that is transferred over the Internet.
8. Which of the following is the most important client to back up in the cloud ?
a) Windows
b) Mac
c) Linux
d) All of the mentioned
View Answer
a) Windows
b) Mac
c) Linux
d) All of the mentioned
View Answer
Answer:d
Explanation:Cloud storage solution should have multiplatform support.
Explanation:Cloud storage solution should have multiplatform support.
9. Which of the following service does not support backup on Linux platform ?
a) Backblaze
b) Crashplan
c) Datapreserve
d) ADrive
View Answer
a) Backblaze
b) Crashplan
c) Datapreserve
d) ADrive
View Answer
Answer:a
Explanation:Data backed up to the cloud cannot be viewed without adequate safeguards or restrictions due to legal regulations.
Explanation:Data backed up to the cloud cannot be viewed without adequate safeguards or restrictions due to legal regulations.
10. Which of the following is least important feature of cloud storage listed below ?
a) Multisite storage or replication
b) 24×7 technical support
c) Data versioning
d) All of the mentioned
View Answer
a) Multisite storage or replication
b) 24×7 technical support
c) Data versioning
d) All of the mentioned
View Answer
Answer:a
Explanation:Data versioning has ability to retrieve historical versions of files from different backups.
Explanation:Data versioning has ability to retrieve historical versions of files from different backups.