April 26, 2019

Software Architectures - MCQS

Note: We have tried uploading as much as we can, there may be 4 to 6 questions which you wouldn't find it here but surely we will upload it soon. So stay tuned. At last, Thanks to Pintu one of our pro-active user who helped in this a lot. 

Question
“Partitioning of data would benefit performance” belongs to
Select one:
a. All of the given choices
b. Resource Mgmt of performance
c. Co-ordination model of performance
d. Data Model of performance

The correct answer is: Data Model of performance

Question
Which of the following is not related to Resource Mgmt of Performance
Select one:
a. Maintaining multiple copies of key data would benefit performance
b. System elements that need to be aware of, and manage, time and other performance-critical resources
c. Process/thread models
d. Prioritization of resources

The correct answer is: Prioritization of resources

Question
Information hiding methods is one of the
Select one:
a. Availability tactic
b. Reliability tactic
c. Usability tactic
d. Modifiabilty tactic

The correct answer is: Modifiabilty tactic

Question
Utility tree is to represeting
Select one:
a. Architecturally significant requirement (ASR)
b. Functional requirement
c. Stakeholders requirement
d. Business requirement

The correct answer is: Architecturally significant requirement (ASR)

Question
Which requirements can affect binding time decisions out of the following mentioned?
Select one:
a. Configurations
b. Portability
c. Regional distinctions
d. All of the choices given

The correct answer is: All of the choices given

Question
One of the statements given below is not true with respect to stakeholders' priorities. Which one?
Select one:
Database Designer: Information security issues?
Users/Customers: How easy it is to use?
Release & Configuration Manager: How do I replace of a subsystem with minimal impact ?
Application Development team: How do I plan for division of work?

The correct answer is: Release & Configuration Manager: How do I replace of a subsystem with minimal impact ?

Question
Decomposition,Uses,Layered and class are keywords used in
Select one:
a. Module structure
b. Allocation structure
c. Structure of structure
d. Component and connector structure

The correct answer is: Module structure

Question
Identification of potential quality attributes from business goals is the measure step of
Select one:
a. ASR
b. QAW
c. PALM
d. Utility Tree

The correct answer is: PALM

Question
Methods to improve Usability include (Pick the wrong answer)
Select one:
a. Intuitive UI
b. Undo / redo feature
c. Displaying status
d. Asking user to enter name twice

The correct answer is: Asking user to enter name twice

Question
One of the statements given below is not true with respect to stakeholders' priorities. Which one?
Select one:
a. Database Designer: Information security issues?
b. Application Development team: How do I plan for division of work?
c. Users/Customers: How easy it is to use?
d. Release & Configuration Manager: How do I replace of a subsystem with minimal impact ?

The correct answer is: Release & Configuration Manager: How do I replace of a subsystem with minimal impact ?

Question
Architecture of software is based on?

Select one:
A. Requirements
B. Design
C. Design and requirements
D. neither Design nor requirements

The correct answer is: Requirements

Question
Architectural pattern that best fits online flight booking application is

Select one:
A. Distributed Architecture
B. Model View Controller Architecture
C. Layer Architecture
D. Service Oriented Architecture

The correct answer is: Model View Controller Architecture

Question
Which of the following represents a Hierarchical organization?

Select one:
Client-Server
Deployment
Layered Structure
Decomposition

The correct answer is: Layered Structure

Question
Example(s) of Interchangeable software components

Select one:
A. All of these
B. Commercial off-the-shelf components
C. publicly available apps
D. open source software

The correct answer is: All of these

Question
Ability to “continuously provide”  service without failure means

Select one:
Performance
Usability
Reliability
Availability

The correct answer is: Reliability

Question
Which of the following does not appear on a diagram describing the WIndows Architecture?

Select one:
User Mode
SQLite
Kernel Mode
DLLs

The correct answer is: SQLite

Question
Deployment, implementation and work assignmnet are the keywords used in
Select one:
a. Component and connector structure
b. Structure of structure
c. Module structure
d. Allocation structure

The correct answer is: Allocation structure

Question
How is the system to relate to non-software structures in its environment such as CPU
Select one:
a. Component and connector structure
b. Structure of structure
c. Module structure
d. Allocation structure

The correct answer is: Allocation structure

Question
Learnability feature of usability attribute provides
Select one:
a. User familiarity to the system
b. Confidence to the user
c. Minimizing the impact of error
d. Adopt user need

The correct answer is: User familiarity to the system

Question
Why is software architecture called vehicle for stakeholder communication?
Select one:
a. Architecture provides a common language in which different concerns can be expressed
b. Architecture is more of technical in nature and not meant for all stakeholders
c. Both a and b
d. Each stakeholder of a software system is concerned with different characteristics of the system affected by architecture

The correct answer is: Both a and b

Question
Which software structure of module structure is useful for "implementing systems on top of 'virtual machine' portability?
Select one:
a. Class
b. Layered
c. Uses
d. Decomposition

The correct answer is: Layered

Question
Record and Playback is a

Select one:
Strategy for one of the testabilty tactics
New feature in modern music web apps
Performance enhancing tactics
Methodology to ensure the security feature of the system

Question
QAW(Quality Attribute Workshop)  is focused on:

Select one:
Reference model level concerns
System level concerns
None of the above
Component level concerns

The correct answer is: System level concerns

Question
---------------- pattern facilitates accessing shared resources and services for large numbers of distributed distributed clients.

Select one:
A. Web server
B. Client server
C. Data server
D. Proxy server

The correct answer is: Client server

Question
How do developing organizations influence by architects?

Select one:
A. Long term business
B. All of the mentioned
C. Organization structure
D. Immediate business

The correct answer is: All of the mentioned

Question
----------------- pattern suggests a solution in which components interact with via announced messages or events.

Select one:
A. Newspaper
B. Bookkeeper
C. Librarian
D. Publish Subscribe

The correct answer is: Publish Subscribe

Question
------------- pattern set a system of “equal” distributed computational entities connected to each other via a common protocol to self organize and achieve high availability and implacability.

Select one:
A. Agents
B. ATM
C. Bots
D. P2P

The correct answer is: P2P

Question
What are the concerns raised for the scenario selection procedure?

Select one:
A. How would we know if the vendor representatives were being factual?
B. Both these
C. None
D. Does the locality of change necessarily yield higher cost?

The correct answer is: How would we know if the vendor representatives were being factual?

Question
The module B expects A to write the count of total transactions handled at a particular memory location. The dependency of B on A is of

Select one:
A. Data semantics dependency
B. Location dependency
C. Data type dependency
D. Sequence dependency

The correct answer is: Data semantics dependency

Question
Which of the following can be included under observable measure?

Select one:
A. How easy it is to integrate?
B. How well the systems during execution satisfy its behavioral requirements?
C. How easy it is to test and modify?
D. All of the mentioned

The correct answer is: How well the systems during execution satisfy its behavioral requirements?

Question
The important categorie(s) of architecture structure is / are

Select one:
A. All of these mentioned
B. Allocation
C. Component and Connector
D. Module

The correct answer is: All of these mentioned

Question
In ----------------- pattern interaction, persistent data is exchanged between multiple data accessors and at least one shared data store.

Select one:
A. Shared Data
B. NDF
C. DBMS
D. Shared Object

The correct answer is:  Shared Data

Question
What is the main goal for the choice of scenarios?

Select one:
A. They should reflect the important quality requirements
B. There be a sufficient number to reflect the views of all the stakeholders
C. Both mentioned
D. None mentioned

The correct answer is: There be a sufficient number to reflect the views of all the stakeholders

Question
Which of the following is not a performance tactic?

Select one:
A. Resource Demand
B. Resource Management
C. Resource Monitor
D. Resource Arbitration

The correct answer is: Resource Monitor

Question
There are several modules that calls a service provided by A. What is the implicit dependency on A?

Select one:
A. Quality of service provided by A
B. Semantics of the result generated by A
C. the fact that A shares the same memory location of these calling modules
D. The assumption that A exists when calling the service of A
The assumption that A exists when calling the service of A

The correct answer is: The assumption that A exists when calling the service of A

Question
An on-line tax-filing application uploads the form-16 document from the employer and it fills the tax return form of an employee once she logs into the system. The file-tax-return button submits the return form and also deducts additional tax amount from her registered credit card. From quality attribute perspective, this application improves

Select one:
A. interoperability
B. performance
C. usability
D. availability

The correct answer is: usability

Question
Architecture based process includes which of the following

Select one:
A. Creating the business case for the system
B. Analyzing or valuating the architecture
C. Understanding the requirements
D. All of these mentioned

The correct answer is: All of these mentioned

Question
Adding an intermediate component between two interacting modules in an application will improve:

Select one:
A. Security of the System
B. Reliability of the System
C. Availability of the System
D. Modifiability of the System

The correct answer is: Modifiability of the System

Question
What is architectural style?

Select one:
A. Architectural style is a description of component types
B. It is a pattern of run-time control
C. All of these mentioned
D. It is set of constraints on architecture

The correct answer is: All of these mentioned

Question
What would happen if different organization were given same set of requirements?

Select one:
A. It will produce same architecture
B. It may or may not produce same architecture
C. None of the mentioned
D. It will produce different architecture

The correct answer is: None of the mentioned

Question
Availability ensures

Select one:
A. Attainment of reliability
B. All of these mentioned
C. Availability ensures
D. Minimize service outage time by fault reduction

The correct answer is: All of these mentioned

Question
------------- pattern splits system into a number of computationally independent execution structures to achieve optimized usage of resources.

Select one:
A. Layers
B. Multi tier
C. Agent
D. Broker

The correct answer is: Multi tier

Question
In a GUI application, when a user presses a button an action event is generated. What is action event in a general quality scenario?

Select one:
A. Artifact
B. Stimulus
C. Response
D. Source

The correct answer is: Stimulus

Question
------------------ pattern is a tactic to achieve highly efficient processing of enormous volumes of data at petabyte scale.

Select one:
A. Map Reduce
B. Supercomputer
C. Shift Reduce
D. Goggle

The correct answer is: Map Reduce

Question
------------------------ is a tactic to achieve Security.

Select one:
A. Maintain Audit Trail
B. License Key
C. Discover
D. copyright

The correct answer is: Maintain Audit Trail

Question
There is a monitor that records the status of the system during runtime. This is an example of

Select one:
A. Modifiability of the System
B. Availability of the System
C. Security of the System
D. Reliability of the System

The correct answer is: Security of the System

Question
--------------- pattern helps to achieve separation of concerns such that modules of system may be independently developed and maintained.

Select one:
A. SOA
B. Microkernel
C. Layered
D. MVC

The correct answer is: Layered

Question
The architects are influenced by which of the following factors?

Select one:
A. Background and experience of the architects
B. Customers and end users
C. Developing organization
D. All of these mentioned Correct

The correct answer is: All of these mentioned

Question
-------------- pattern describes a collection of distributed components that provide and/or consume the services.

Select one:
A. SOA
B. Client server
C. P2P
D. Broker

The correct answer is: SOA

Question
Source of stimulus can be

Select one:
A. Any actuator
B. Stimulus
C. None of these mentioned
D. Environment

The correct answer is: Any actuator

Question
----------------- pattern is characterized by successive transformation of streams of data using generic, loosely coupled components.

Select one:
A. Blackboard
B. Pipes and filters
C. Classroom
D. Abstraction

The correct answer is: Pipes and filters

Question
Which of the following is the main goal for the choice of scenarios?

Select one:
A. They should reflect the important quality requirements
B. Both
C. None of these
D. There be a sufficient number to reflect the views of all the stakeholders

The correct answer is: Both

Question
The incorrect method for structural design is?

Select one:
A. More procedural approach
B. Handling of larger and more complex products
C. Transition of problem models to solution models
D. Designing Object oriented systems

The correct answer is: Handling of larger and more complex products

Question
The proto scenarios recorded on flip charts as phrases as which of the following?

Select one:
A. WWW client access
B. Double number of user
C. All of these mentioned
D. Degraded Operation

The correct answer is: All of these mentioned

Question
Denial of Service attack affects the __________ of the system.

Select one:
A. All of these
B. Usability
C. Availability
D. Security

The correct answer is: Availability

Question
Tactics which ensures interoperability includes

Select one:
A. Orchestrate and Tailor interface
B. Both of these
C. None of these
D. Discover service and Tailor interface

The correct answer is: Both of these

Question
To capture data store and access to data from the store by various components you use

Select one:
A. Module dependency structure
B. component and hardware dependency
C. component connector structure
D. work-allocation of modules

The correct answer is: component connector structure

Question
--------------- pattern defines a runtime component that mediates the communication between a number of clients and servers.

Select one:
A. Proxy
B. Middleware
C. Broker
D. Load balancer

The correct answer is: Broker

Question
---------------- pattern separates out presentation from functionality of the system.

Select one:
A. Maps
B. UI/UX
C. MVC
D. Controller

The correct answer is: MVC

Question
Authorizing the user is a __________

Select one:
A. Usability tactic
B. Security tactic
C. Availability tactic
D. Performance tactic

The correct answer is: Security tactic

Question
Which of the following is the incorrect sequence Summary Steps for scenario selection process?

Select one:
A. Method presentation
B. Refinement and selection
C. Participant buy-in and expression of concerns and issues
D. All of these mentioned

The correct answer is: Participant buy-in and expression of concerns and issues

Question
Which among the following are true with regards to the architecture business cycle?

Select one:
A. All of these mentioned
B. None of these mentioned
C. The architecture affects the structure of developing organizations
D. The architecture can affect the enterprise goals of the developing organizations

The correct answer is: The architecture affects the structure of developing organizations

Question
Here are two applications with the following operational failure characteristics on a given day. Application 1 crashed 10 times and it took 5min to restart every time after the crash. Application 2 crashed 20 times and it took 2min to restart.

Which one has a better availability?

Select one:
A. 1 has the better availability
B. 1 and 2 has more or less the same availability
C. 2 has the better availability
D. their availability values can't be compared

The correct answer is: 2 has the better availability

Question
What are the steps involved in Financial management system?

Select one:
A. choosing Scenarios And Achieving Deep understanding
B. Scenario Selection Process
C. Observation on the scenario selection process
D. all of these

The correct answer is: all of these

Question
Which of the following are scenarios for the financial management system analysis?

Select one:
A. Multiple fiscal year budgets
B. All of these mentioned
C. Degraded operation mode
D. Bottom Up person

The correct answer is: All of these mentioned

Question
A representation of a coherent set of architectural elements, as written by and read by system stakeholders is

Select one:
A. Allocation structure
B. Component and Connector structure
C. Views
D. Module structure

The correct answer is: Views

Question
The architect designs the allocation of services to hosts so that only limited services are available on each host. It will help to improve

Select one:
A. Security of the System
B. Availability of the System
C. Reliability of the System
D. Modifiability of the System

The correct answer is: Security of the System

Question
Resynchoronizing the state of a repaired component with the current state of operation and then re-introducing this component is the tactic for improving which of the following attribute.

Select one:
A. Performance
B. Security
C. Testability
D. Availability

The correct answer is: Availability

Question
Reduction of coupling between modules is a tactic for

Select one:
A. usability tactic
B. Availability tactic
C. Modifiability tactic
D. Security tactic

The correct answer is: Modifiability tactic

Question
While describing a deployment containing hardware infrastructure, you should

Select one:
A. show relationship between a process component and a hardware infrastructure
B. show relationship between a hardware component and a software module/sub-modules
C. show a relationship between a module and a data item that the module uses
D. show a relationship between a package and a hardware infrastructure

The correct answer is: show relationship between a process component and a hardware infrastructure

Data Storage Technologies and Networks - Mid Sem Solution


Note: We have tried solving the question paper in a very short time span as per our understanding and the study material we had. Feel free to contact us through comment box or through email if you have some descriptive answer.



Question) 
It is required to transfer a file of size 8000 bytes at a rate of 4MB/sec with a seek time of 12ms. The disk is rotating at 1000 RPM. Compute the time required for the transfer?
Answer)
Transfer time (T = b/r*N)
  • b number of bytes to be transferred 
  • N number of bytes on a track
  • r is rotation speed in revolution per second
Question) How is the priority sequence established in a wide SCSI environment?
Answer)
In a wide SCSI, the device IDs from 8 to 15 have the highest priority, but the entire sequence of wide SCSI-IDs has lower priority than narrow SCSI IDs.

Therefore, the overall priority sequence for a wide SCSI is 7, 6, 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, and 8.

Question) Firewall configuration is difficult for which NFS version? Justify.
Answer)
NFS is a client server protocol that allows users to share files across a network. There are some problems with NFS as stated below:
● NFS relies on the inherently insecure UDP protocol
● Transactions between host and client are NOT encrypted
● Hosts and users cannot be easily authenticated, IP Spoofing is possible
● Persmissions are granted by normal access rules
● Firewall configuration is difficult because of the way NFS daemons work

NFSv3 requires dynamic ports between the NFS server and client which can cause problems getting through your firewall.

Question)
What are the three types of nodes maintained by JFFS2? Mention percentage hit by ‘Garbage Collector’ to reclaims space from various types of nodes.
Answer)
JFFS is a log structured file system, Nodes containing data and metadata are stored on the flash chips sequentially. There are three types of nodes defined and implemented by JFFS2. These are as follows:

  1. JFFS2_NODETYPE_INODE - It contains all the inode metadata, as well as potentially a range of data belonging to the inode. However, it no longer contains a file name or the number of the parent inode.
  2. JFFS2_NODETYPE_DIRENT - this node represents a directory entry, or a link to an inode. It contains the inode number of the directory in which the link is found, the name of the link and the inode number of the inode to which the link refers. 
  3. JFFS2_NODETYPE_CLEANMARKER -- this node is written to a newly erased block to show that the erase operation has completed successfully and the block may safely be used for storage.
Garbage Collector (GC):
  • JFFS2 has a Garbage Collector (GC). The GC is calld directly from JFFS2 or from a background thread called GC thread.
  • If a user process tries to allocate space for a write and there is not enought free space then it calls the GC to produce the neccesery free space if it is possible.
Question) Can we install SAMBA on Windows? Justify. What is the name of the file to configure SAMBA?
Answer)
Samba is an open-source software suite that runs on Unix/Linux based platforms but is able to communicate with Windows clients like a native application. So Samba is able to provide this service by employing the Common Internet File System (CIFS).

Can we install on windows ? - No we can not install it on Windows. Samba can be run on many different platforms including Linux, Unix, OpenVMS and operating systems other than Windows and allows the user to interact with a Windows client or server natively. It can basically be described as the Standard Windows interoperability suite of programs for Linux and Unix.

Name of file to configure SAMBA: smb.conf

Question )
In a SCSI based interface, a target has to support multiple initiators. Explain how a target will handle an incoming read request when it is busy, giving complete steps of read request between such initiator and a target components (handling multiple imitators) of a SCSI interface. Clearly indicate any assumptions made.

Answer)
Assumptions :Let us assume we have one target T1 and three initiators I1, I2 and I3 with below SCSI IDs :

Initiator  SCSI ID
I1              6
I2              3
I3              5

The device with SCSI ID 7 has the highest priority on the SCSI bus and is usually assigned to the host adapter. The priority of other SCSI IDs is descending from 6 to 0.

Phases of SCSI bus :
There are basically 3 phases :
Bus Free Phase
–Bus is not being used by anyone

Arbitration Phase
–One or more initiators request use of the bus and
the one with the highest priority (SCSI ID order) is allowed to proceed

Selection / Re-selection phase
–Initiator asserts BUS BUSY signal and
•places target’s address on the bus thus establishing a connection/session
–Re-selection applies for a target resuming an interrupted operation:
•target asserts BUS BUSY signal and places initiator’s address on the bus.

Steps for Bus Phase Sequence Read Operation
  1. When bus is free, initiator enters into arbitration (with other possible initiators).
  2. Since we have multiple initiators on the same SCSI bus ,the selection phase allows arbitration for control of the bus.According to our assumptions I1 has the highest priority therefore I1 will be the first initiator to set  connection with target.
  3. On arbitration, initiator I1 selects the bus and places target address on bus.
  4. Target acknowledges selection by a message
  5. Initiator I1 sends command
  6. Target acknowledges command by a message
  7. The bus will be in free status after the target sends the status as FREE
  8. After the initiator I1 is successful,I3 will be able to place target address on the bus as I3 is on second priority and sends selection by a message.
  9. Same steps from 4 to 8 are performed for I3 and I2.

April 24, 2019

Data Storage Technologies and Networks - MCQS

Question
Which of the following RAID levels gives maximum usable capacity?

Select one:
A. RAID 0
B. RAID 5
C. RAID 6
D. RAID 1

The correct answer is:  RAID 0

Question
Which logical operation is used for computing parity?

Select one:
A. Exclusive OR
B. Exclusive NOR
C. Inclusive NOR
D. Inclusive OR

The correct answer is: Exclusive OR

Question
Which of the following RAID implementation does not allow data recovery in case of disk failure?

Select one:
A. RAID 5
B. RAID 1
C. RAID 0
D. RAID 10

The correct answer is: RAID 0

Question
What is a hot Spare?

Select one:
A. It is a spare drive within a RAID array.
B. It is a drive that can be plugged in while the Storage array is powered on
C. It is an extra drive provided by the vendor to be plugged in in case of disk failure
D. It is a disk that is over heated

The correct answer is: It is a spare drive within a RAID array.

Question
What is a blast zone in RAID?

Select one:
A. It is the portion of disk burnt due to overheating
B. It is the area of impact when data is lost from a failed RAID set.
C. It is the portion platter damaged due to head crash
D. It is the area of impact when the disk explodes.

The correct answer is: It is the area of impact when data is lost from a failed RAID set.

Question
Which of the following statement is true for RAID 5?

Select one:
A. RAID 5 uses block level striping with distributed parity
B. RAID 5 is a hybrid of mirror sets and stripe sets
C. RAID 5 uses block level striping with double distributed parity
D. RAID 5 uses block level striping with a dedicated parity drive

The correct answer is: RAID 5 uses block level striping with distributed parity

Question
Journaling is preferred for

Select one:
A. Storing metadata
B. Storing logs
C. Faster file system recovery
D. Faster write operation

The correct answer is: Storing Faster file system recovery

Question
Examples of Journaling file system

Select one:
A. JFS
B. Ext2
C. Ext3
D. UFS

The correct answer is: Ext3

Question
Wear leveling affects

Select one:
A. RAM
B. Optical storage
C. Hard disk
D. Flash

The correct answer is: Flash

Question
Every File or directory has unique

Select one:
A. Inode
B. Directory
C. Pathname
D. Inode & pathname

The correct answer is: Inode & pathname

Question
Which of the following is not a non volatile storage device?

Select one:
a. Hard Disk
b. Memory Stick
c. NVRAM
d. Random Access Memory

The correct answer is: Random Access Memory

Question
Solid State devices are best suited for ______________ writes & _________________ reads.

Select one:
A. Frequent Random, Frequent Sequential
B. Frequent Sequential, Infrequent Random
C. Infrequent Sequential , Frequent Random
D. Infrequent Random, Frequent Sequential

The correct answer is: Infrequent Sequential , Frequent Random

Question
Which of the following is sequential access storage device?

Select one:
A. CD-ROM
B. Main Memory
C. Hard Disk
D. Tape Cartridge

The correct answer is: Tape Cartridge

Question
A “Logical Volume Manager” helps in

Select one:
A. Virtualizing storage
B. provide direct access to the underlying storage
C. Manage disk space efficiently without having to know the actual hardware details
D. Both storage virtualization and efficient disk space management

The correct answer is: Both storage virtualization and efficient disk space management

Question
Physical Volumes are

Select one:
A. None of these mentioned
B. Disk or disk partitions used to construct logical volumes
C. The space on a physical storage that represent a logical volume
D. A bunch of disks put together that can be made into a logical volume

The correct answer is: Disk or disk partitions used to construct logical volumes

Question
Which of the following are true. Logical Volumes _____

Select one:
A. Can span across multiple volume groups
B. Can span across multiple physical volumes
C. Can be constructed only using a single physical disk
D. None these mentioned

The correct answer is: Can span across multiple physical volumes

Question
Fileystem is created using command

Select one:
A. Mkfs
B. Fsck
C. defrag
D. Format

The correct answer is: Mkfs

Question
Concatenation is the technique of

Select one:
A. Increasing the size of a volume by adding more disks
B. Adding physical volumes together to make a volume group
C. writing a block of data onto one disk and then a block onto another disk in an alternate fashion
D. Filling up a physical volume completely before writing to the next one in a logical volume

The correct answer is: Filling up a physical volume completely before writing to the next one in a logical volume

Question
A MySQL database is involved in persisting random writes to the storage medium quantified by Kilobytes of block data. Which of the below is the suitable metric to measure the performance of the disk operations

Select one:
A. Input Output Operations Per Second
B. Mega Bytes Per Second

The correct answer is: Input Output Operations Per Second

Question
Which of the below attributes to the latency in the data transfer between application and storage Hard disks?

Select one:
A. Head Seek Time between the Platters
B. None of these
C. Cache Miss
D. Disk Controller Queuing

The correct answer is: Cache Miss

Question
MLC has _______________ PE cycles and _______________ in performance compared to SLC SSDs. Where - MLC- MultiLevelCell  ; SLC-SingleLevelCell

Select one:
A. More, Low
B. Less , Low
C. Less , High
D. More ,High

The correct answer is: Less, Low

Question
In a Flash Memory, how is the content of a cell changed to 1 from 0?

Select one:
A. By erasing the content of the cell
B. By block erase operation and rewriting the content of the block
C. By writing 1 to the cell
D. By erasing the content of the cell before writing 1

The correct answer is:  By block erase operation and rewriting the content of the block

Question
Which of the following statement is true for a Single Level Cell?

Select one:
A. It has the longest life span
B. It allows more data storage
C. Singe level cells are cheap
D. It offers medium performance as compared to other formats

The correct answer is: It has the longest life span

Question
Which of the following is applicable to Enterprise class solid state devices?

Select one:
A. They have more over provisioned capacity
B. Warranty terms are same as all Solid state devices
C. They have the simple controller firmware
D. They have same amount of cache is not less than consumer class devices

The correct answer is: They have more over provisioned capacity

Question
Which of the following statement is true about Striping?

Select one:
A. A stripe is stored on a single disk
B. Striping reduces the disk performance
C. Striping helps in data recovery
D. Striping parallelises I/O operation

The correct answer is: Striping parallelises I/O operation

Question
Do iSCSI storage mandatory to required switch?

Select one:
Yes
No
None
a & b both

The correct answer is: No

Question
Best I/O Technique for low volume data transfer

Select one:
Polling
Interrupt Driven
DMA
b and c

The correct answer is: Interrupt Driven

Question
What is the memory bandwidth requirement of a machine executing 4*105 instructions per second, average instruction size of 3.8 bits and 7.2 bits of average operand size per instruction?

Select one:
1.52 Mbps
0.72 Mbps
2.88 Mbps
4.4 Mbps

The correct answer is: 4.4 Mbps

Question
Which version of NFS Mandates strong security

Select one:
NFSv1
NFSv2
NFSv3
NFSv4

The correct answer is: NFSv4

Question
Estimate the sustained transfer rate of a drive if disk drive spins at 7200 RPM, has a sector size of 512 bytes, and holds 160 sectors per track around

Select one:
9400 KB/s
9600 KB/s
9800 KB/s
10000 KB/s

The correct answer is: 9800 KB/s

Question
Which storage Technology uses low level disk drive access commands like READ block, WRITE block and READ capacity

Select one:
NAS
SAN
DAS
All the above

The correct answer is: SAN

Question
How do we meet memory bandwidth requirements?

Select one:
L1 cache, L2 cache and DRAM
Direct Attached Storage and Network Storage
Archival Storage
All the above

The correct answer is: All the above

Question
PCI Bus Lines contains

Select one:
Control Lines
Data Lines
Address Lines
All the above

The correct answer is: All the above

Question
How many disk failure can disk failure can be withstood by RAID 6?

Select one:
1
2
3
4

The correct answer is: 2

Question
Which of the following model makes the server to keep track of cached copies and notifies them on update

Select one:
Asynchronous writing model
Cache verification model
Callback model
Leasing model

The correct answer is: Callback model

Question
What is the capacity of the disk with 5 platters. 2 surfaces per platter, 20000 tracks per surface, 300 sectors per track and 512 bytes per sector

Select one:
30.72GB
24.40GB
21.40GB
15.16GB

The correct answer is: 30.72GB

Question
If average latency is 2.99 ms and average seeks time is 4.7 ms, then IOPS of the disk will be?

Select one:
129
130
128
131

The correct answer is: 130

Question
A certain hard disk has 16 cylinders, 480 tracks per cylinder, 32 sectors per track, and 512 bytes per sector. What is its storage capacity?

Select one:
125,829,120 bytes
125,929,120 bytes
125,729,120 bytes

125,629,120 bytes

The correct answer is: 125,829,120 bytes

Question
If MTTF of  a disk is 80000hrs what us MTTF of an array of 8 disks

Select one:
640000 hrs
10000 hrs
80000 hrs
40000 hrs

The correct answer is: 10000 hrs

Question
Identify a network file protocol in the below mentioned set

Select one:
FC
CIFS
SCSI
NAS

The correct answer is: CIFS

Question
Which option is dedicated for file sharing?

Select one:
bimodal
network attached storage
stealth
storage area network

The correct answer is: network attached storage

Question
If read and write performance is the only criterion, which would you choose?

Select one:
RAID 0
RAID 1
RAID 5
RAID 50

The correct answer is: RAID 0

Question
Which of the following RAID levels guarantees double disk failure protection?

Select one:
Raid 5
Raid 6
Raid 0+1
Raid 1+0

The correct answer is: Raid 6

Question
In SAN network which type of switch used typically?

Select one:
Director switch
Intelligent switch
IP switch
Hub

The correct answer is: Intelligent switch

April 22, 2019

Cloud Computing - MCQS

Question
Which of these is not a major type of cloud computing usage?

Select one:
a. Hardware as a Service
b. Platform as a Service
c. Software as a Service
d. Software as a Service

The correct answer is: Hardware as a Service

Question
Virtualization facilitates multiple machines on the same physical machine with

Select one:
a. Same OS & different versions
b. All of the above
c. Same OS & same versions
d. Different OS & different versions

The correct answer is: All of the above

Question
Which is not an approach to virtualization

Select one:
a. Partial virtualization
b. Lightweight virtualization
c. Full virtualization
d. Para virtualization

The correct answer is: Partial virtualization

Question
Live migration of VMs helps in

Select one:
a. Maintenance
b. Load balancing
c. All of the above
d. Availability

The correct answer is: All of the above

Question
Live migration involves

Select one:
a. Downtime of a few minutes
b. Loss of service
c. Downtime of a few milliseconds
d. No downtime

The correct answer is: Downtime of a few milliseconds

Question
Full virtualization

Select one:
a. Simulates hardware within software
b. Has VMs with the same OS
c. Clones images
d. Alters the guest OS

The correct answer is: Simulates hardware within software

Question
VMM is

Select one:
a. A virtual machine
b. Hardware
c. Host OS
d. A layer of software

The correct answer is: A layer of software

Question
VMM facilitates sharing of

Select one:
a. Memory & I/O
b. CPU, memory & I/O
c. CPU & memory
d. I/O & CPU

The correct answer is: CPU, memory & I/O

Question
The BEST way to define Virtualization in cloud computing is

Select one:
a. Virtualization enables simulating compute, network, and storage service platforms from the underlying virtual hardware
b. Virtualization enables abstracting compute, network, and storage service platforms from the underlying physical hardware
c. Virtualization enables realization of compute, network, and storage service platforms from the underlying virtual hardware
d. Virtualization enables emulating compute, network, and storage service platforms from the underlying virtual hardware

The correct answer is: Virtualization enables abstracting compute, network, and storage service platforms from the underlying physical hardware

Question
Which one of these statement is NOT fully correct

Select one:
a. Cloud is an exact equivalent of grid computing
b. Cloud makes notion of “Pay for what you use”, “infinite availability- use as much you want”.
c. Cloud can exist without Virtualization, although it will be difficult and inefficient.
d. As per NIST, one of the essential charecteristics of a cloud computing infrastructure is "Measured Service".

The correct answer is: Cloud is an exact equivalent of grid computing

Question
Which one of the followings is NOT an essential charecteristics of cloud infrastructure as per NIST?

Select one:
a. Broad Network Access
b. Resources Pooling
c. Rapid Elasticity
d. Independent of devices'form factor

The correct answer is: Independent of devices'form factor

Question
Cloud service consist of

Select one:
a. Software, Hardware, Infrastructure
b. Platform, Software, Infrastructure
c. Platform, Hardware, Infrastructure

The correct answer is: Platform, Software, Infrastructure

Question
What does Virtualization do? Select the BEST answer.

Select one:
a. Each “guest” OS is managed by a Virtual Machine Monitor (VMM), also known as a hypervisor.
b. It is a means of separating hardware from a single operating system.
c. All of the above
d. Virtualization allows multiple operating system instances to run concurrently on a single computer

The correct answer is: All of the above

Question
Which one is NOT generally a change after Virtualization?

Select one:
a. Virtual machines can be provisioned to any system
b. Hardware-independence of operating system and applications
c. Can manage OS and application as a single unit by encapsulating them into virtual machines.
d. Software and hardware tightly coupled

The correct answer is: Software and hardware tightly coupled

Question
A configured client server network is required to be provisioned. You would go for

Select one:
a. SaaS
b. IaaS
c. NaaS
d. PaaS

The correct answer is: IaaS

Question
What are the goals of Hypervisor design?

Select one:
a. Scalability
b. All of the above
c. Reliability
d. Isolation

The correct answer is: All of the above

Question
Which one of the statement is generally NOT correct for Microkernelized Hypervisor?

Select one:
a. Drivers run within guests
b. Simple partitioning functionality
c. Increase reliability and minimize lowest level of the TCB
d. Contains its own drivers model

The correct answer is: Contains its own drivers model

Question
In multiple VM processing, CPU is alloted to the different processes in form of:

Select one:
a. Space slices by the OS
b. Different CPUs are allocated to different processes
c. Time slices by the OS
d. Frequecy slices by the OS

The correct answer is: Time slices by the OS

Question
Which of the statement is generally NOT correct for Full Virtualization?

Select one:
a. This is known as hardware-assisted virtualization, and improves performance significantly
b. The biggest advantage to this approach is its flexibility.
c. There are significant performance problems in trying to emulate a complete set of hardware in software
d. Hypervisor provides a fully emulated machine in which an operating system can run

The correct answer is: This is known as hardware-assisted virtualization, and improves performance significantly

Question
Which of the following is true of cloud computing?

Select one:
a. It's always going to be less expensive and more secure than local computing.
b. Only a few small companies are investing in the technology, making it a risky venture.
c. You can access your data from any computer in the world, as long as you have an Internet connection.

The correct answer is: You can access your data from any computer in the world, as long as you have an Internet connection.

Question
Which of the following is deployment model?

Select one:
a. Public
b. Private
c. All of the above
d. Hybrid

The correct answer is: All of the above

Question
The ________ cloud infrastructure is operated for the exclusive use of an organization.

Select one:
a. All of the mentioned
b. Public
c. Community
d. Private

The correct answer is: Private

Question
Following is not a feature of Cloud Computing:

Select one:
a. Rapid Provisioning
b. On Demand
c. None of the above
d. Unambiguous
e. Shared Pool

The correct answer is: Unambiguous

Question
Cloud computing is

Select one:
a. Utility computing
b. Peer to peer computing
c. Mobile computing
d. All of these

The correct answer is: Utility computing

Question
Bare metal hypervisor sits on top of

Select one:
a. None of the above
b. Physical Hardware
c. Virtualized hardware
d. Operating System

The correct answer is: Physical Hardware

Network Security - MCQS

Question
Consider these statements and state which are true.
i)   Encoding and encryption change the data format.
ii)  Encoding is a reversible process, while encryption is not.
iii) Both Encoding and Encryption are reversible processes.
iv)  Any third party will be able to reverse an encoded data,but not an encrypted data.

Select one:
i), iii) and iv)
ii) and iv)
i) and iv)
i),  ii) and iv)

The correct answer is: i), iii) and iv)

Question
Which of the following attacks is not an attack on Integrity?

Select one:
Modification
Replay
Denial Of Service
Masquerading

The correct answer is:: Denial Of Service

Question
I sent a data set {A,B,C,D} to a recipient which got received as {B,A,D,C}.

Select one:
Data security is compromised
Data integrity is lost
Confidentiality is lost
Data availability is compromised

The correct answer is:: Data integrity is lost

Question
A website login mechanim employs both password and verifying a PIN number sent via SMS to registered mobile.

This scenario provides ______
Select one:
High convenience but low security
High convenience and good security
Low convenience and low security
Low convenience but good security

The correct answer is:: Low convenience but good security

Question
A fake email posing as a legitimate email from bank is 

Select one:
Attack on Availability
Masquerading attack
Denial of Service (DOS) attack
Attack on Confidentiality

The correct answer is:: Masquerading attack

Question
Which of these mechanims provide data integrity ?
i) DES Encryption
ii) Asymmetric encryption
iii) SHA Hashing
iv) Hashed-MAC

Select one:
i and iv
i and iii
ii and iii
iii and iv

The correct answer is:: iii and iv

Question
Email attachments typically employ

Select one:
Base64 encoding
Base16 encoding
UTF-8 encoding
URL encoding

The correct answer is:: Base64 encoding

Question
The combination of key exchange, hash and encryption algorithms is termed as _______ in SSL/TLS.     

Select one:
TLS Handshake
Protocol suite
Cipher suite
TLS Records

The correct answer is:: Cipher suite

Question
The protocol ‘POP’ stands for-

Select one:
Personal Office Protocol
Post Office Protocol
Privacy Overall Protocol
Privacy Over Protocol

The correct answer is:: Post Office Protocol

Question
Which is the most secure way to remote login?

Select one:
SSH with public keys
Telnet with password
SSH with password
Telnet with public keys

The correct answer is:: SSH with public keys


Question
The Application layer protocol required for Electronic Mail is:

Select one:
SMTP
HTTP
FTP
SIP

The correct answer is: SMTP

Question
Which of these statements regarding HTTP is true.

Select one:
HTTPS adds security to HTTP POST and PUT messages as this is where password exchange is done.
HTTPS uses the same HTTP message format but  adds a handshake+encryption mechanism.
HTTPS introduces new messages HANDSHAKE and ALERT for bringing in security in HTTP.
HTTPS does not add security to HTTP GET and HEAD messages

The correct answer is: HTTPS uses the same HTTP message format but  adds a handshake + encryption mechanism.

Question
For SSL which is the advised cryptographic algorithm?

Select one:
twofish 128
aes 192
aes 128
blowfish

The correct answer is:: aes 128

Question
In SSL handshake, Server Hello message typically contains

Select one:
List of ciphers for the session and extensions list
Selected cipher for the session and random bytes
Selected cipher for the session and public key of server
Random bytes and public key of server

The correct answer is: Selected cipher for the session and random bytes

Question
Pretty Good Privacy (PGP) is employed in

Select one:
FTP and WWW Security
Email and FTP Security
Email security
Email and WWW Security

The correct answer is:: Email security

Question
What is the common term present in HTTP request and status line?

Select one:
HTTP version number
URL
Method
None of the mentioned

The correct answer is:: HTTP version number

Question
A session symmetric key between two keys is used:

Select one:
Only once
Two times
Multiple times
Dependent on other conditions

The correct answer is:: Only once

Question
Which one of the following is a cryptographic protocol used to secure HTTP connection?

Select one:
Stream Control Transmission Protocol (SCTP)
Pretty Good Privacy (PGP)
Secure Mime(SMIME)
Transport Layer Security (TLS)

The correct answer is:: Transport Layer Security (TLS)

Question
The services provided by application layer are:

Select one:
Network virtual terminal
File transfer, access, and management
Mail service
All of the mentioned

The correct answer is:: All of the mentioned

Question
A group having 30 members uses Symmetric Key Encryption for message transmission.   How many secret keys are needed if all the members need to send secret messages to each other?

Select one:
30
60
435
900

The correct answer is: 435

Question
I - me@gmail.com - tried to email a .jar file to Dinesh. dinesh@company.com . But it got blocked by gmail while attaching.Then I tried sending a .txt file to Dinesh which went through fine. What do you infer? .jar files cannot be sent as

Select one:
A. it is blocked by gmail as .jar files are bigger in size
B. Email uses SMTP which is a Text protocol
C. it is blocked by company.com
D. it is blocked by gmail as it could contain viruses.

The correct answer is: it is blocked by gmail as it could contain viruses.

Question
What is the protocol used between Message User Agent (MUA) and Message Transfer Agent (MTA) in email system.

Select one:
A. HTTP
B. SMTP
C. IMAP
D. POP3

The correct answer is: SMTP

Question
IPSec defines these two protocols:

Select one:
A. PGP; ESP
B. AH; ESP
C. AH; SSL
D. PGP: SSL

The correct answer is: AH; ESP

Question
HTTPS implicitly uses Server certificates. These Server certificates contain ______

Select one:
A. Server's public key, algorithm used and digital signature
B. Server's public key and private key
C. Server's private key, algorithm used and digital signature
D. Server's public key and digital signature

The correct answer is: Server's public key, algorithm used and digital signature

Question
Asymmetric encryption has

Select one:
A. one key for encryption and another key for decryption
B. two keys - one key for public encryption and another for private encryption
C. one public key for doing encryption and decryption and another private key only for decryption
D. only one public key which is shared

The correct answer is: one key for encryption and another key for decryption

Question
IP Header contains

Select one:
A. Source and destination IP addresses and priority numbers
B. Source and destination IP addresses and IP version number
C. Source and destination IP addresses and Port numbers
D. Source and destination IP addresses and sequence numbers

The correct answer is: Source and destination IP addresses and IP version number

Question
Pick the most relevant option. I sent a data set {J,K,L,M,N} to a recipient which got received as {J,K,N}.

Select one:
A. Data integrity is lost
B. Data availability is compromised
C. Both Confidentiality and integrity are compromised
D. Data Confidentiality is compromised

The correct answer is: Data integrity is lost

Question
A data center is secured with 3 outer gates - Og1, Og2, Og3    locked by separate keys - Kog1, Kog2, Kog3 - given to    three personnel - P1, P2, P3. These 3 outer gates lead to 2 inner gates - Ig1, Ig2 - which provide main corridor access. The matching keys - Kig1, Kig2 are given to P2 and P4. The order of acessibility from most access to least access  for the personnel is ____________

Select one:
A. P2, P1, P3, P4
B. P1, P2, P3, P4
C. P4, P3, P2, P1
D. P2, P4, P1, P3

The correct answer is: P2, P1, P3, P4

Question
Pick the closest in meaning to non-repudiation. Manu sends data to Naren. Paari is sniffing the data transfer.

Select one:
A. Naren can verify that data was indeed sent by Manu.
B. Paari is unable to get the original data.
C. Manu can verify if data reached Naren without any change.
D. Naren can verify if the data got changed by Paari

The correct answer is: Naren can verify that data was indeed sent by Manu.

Question
The modes  of IP-Sec are

Select one:
A. Padding mode and Non-padding mode.
B. Secure and Unsecure Mode
C. Tunnel Mode and Transport Mode
D. SPD and SAD mode

The correct answer is: Tunnel Mode and Transport Mode

Question
Of these, Which is the most secure way to remote login?

Select one:
A. SSH with public keys
B. Telnet with password
C. Telnet with public keys
D. SSH with password

The correct answer is: SSH with public keys

Question
Megha's uses a 4-digit bank ATM PIN. Guna peeped in,as Megha keyed-in and found the last two digits of her PIN. Knowing that Megha does not use 0 in her PIN, what is the maximum attempts for Guna to get her PIN correct ?

Select one:
A. 18
B. 81
C. 19
D. 90

The correct answer is: 81

Question
When using HTTPS, a sniffer in a local LAN will be able to

Select one:
A. sniff only the websites/domain but not the URLs
B. sniff only the websties/domain but not the IP addresses
C. sniff only the URLs in the data exchange but not the posted/downloaded data contents.
D. sniff only the HTTP headers in the requests and response

The correct answer is: sniff only the websites/domain but not the URLs

Question
Pick the statement which is true. A network application

Select one:
A. can use both TCP and UDP at the same time, but only maximum of 256 ports. Incorrect
B. cannot use both TCP and UDP at the same time.
C. can use both TCP and UDP at the same time
D. can use both TCP and UDP at the same time, but only maximum of 1024 ports.

The correct answer is: can use both TCP and UDP at the same time

April 17, 2019

Network Security - Mid Sem Solution

Mid-Sem Paper Solutions:


Question:
What are the different types of active security attack ?

Answer:
Security Attack: Any action that compromises the security of information owned by an organization. There are 2 types of attack as shown below.

Active Attack:
An Active attack attempts to alter system resources or effect their operations. The attacker changes the data or harms the system.

Passive Attacks:
The attacker’s goal is to just obtain the information. The attack does not harm the system.

Types of active attacks include:
  • Denial of service (DoS) - It prevents normal use of communication facilities. Slowing down or totally interrupt the service of the system. E.g. multiple requests to bring an exam result server down.
  • Session replay - Subsequent retransmission of a captured message to produce an unauthorized effect. E.g. Bill payment fake reminders.
  • Masquerade - Masquerade attack takes place when one entity pretends to be different entity. E.g. Hoax bank sites. 
  • Message modification - It means that some portion of a message is altered or that message is delayed or reordered to produce an unauthorized effect.
  • Repudiation - Sender denies that it sent the message or the receiver denies that it received the message.
  • Trojans - A Trojan horse, or Trojan, is a type of malicious code or software that looks legitimate but can take control of your computer. A Trojan is designed to damage, disrupt, steal, or in general inflict some other harmful action on your data or network.
Types of passive attack include:
  • Snooping - Data is intercepted by an unauthorized person. E.g. Tapping
  • Traffic Analysis - May be the data is masked, so no information can be extracted but some patterns like - sender, receiver, message length, time of the message etc. can be extracted to make intelligent guesses.

April 15, 2019

Office 365 Admin Center - Digital Skill (TrendNXT L1)

Marks: 10
Set: 1
Question:62



Note: Kindly prepare yourself to score good marks in Office 365 Admin Center L1. This is for TrenDNXT level 1 dumps.

MCQS:




Hope you all guys do well in your exam, Feel free to post your concern in comment box in case of any changes in required question/answer template. 

Software Architecture - Mid Sem Solution

Mid-Sem Paper Solutions:



Question:
Q.1 Choose the most appropriate architectural pattern (one) for the 5 descriptions below. Give reasons for choosing the pattern (in 1-2 line maximum)

1. Wants to split a system into a number of computationally independent execution structures (groups of software and hardware) such as database, business logic, web interface and client, connected by some communication media. The structure is chosen to provide a specific server environment optimized for operational requirements and resource usage.

2. A set of heterogeneous specialized modules which dynamically change their strategies as a response to unpredictable events, and the system has to deal with uncertain knowledge.

3. Wants a system that can be divided into reusable, loosely coupled components that can be flexibly combined and arranged to transform between various data formats.

4. Wants a distributed system with a structure that enables that service users do not need to know the nature or location of service providers.  

5. A program relationship in which one program requests a service or resource from another Program.

Nominees:
(a) Layered 
(b) Broker 
(c) Model-view-controller
(d) Pipe-and-Filter 
(e) Client-Server 
(f) Blackboard 
(g) Service-Oriented 
(h) Publish-Subscribe 
(i)  Map-Reduce

For Practice:
  • Wants a system that quickly can analyze enormous volumes of data by sorting the data and then analyzing the grouped data. -> Map-Reduce
  • Wants to set up a set of equal distributed computational entities that are connected via a common protocol to share their services and provide high availability and scalability. -> Peer-to-peer
Answer:

1. Multi-tier
2. Blackboard
3. Pipe-and-Filter 
4. Broker
5. Client-Server

Question:
Q.2. Write brief notes on followings:

2.1  Discuss whether this statement is true or false: “Architecture is a transferable and reusable model”.
Answer:
Yes, it is true. Architecture can be created as transferable, reusable model that forms the heart of a product line.
Below is some key-point which does prove the importance of this.
Architecture can provide the basis for evolutionary prototyping.
Architecture is the key artifact that allows the architect and project manager to reason about cost and schedule.
By restricting design alternatives, architecture channels the creativity of developers, reducing design and system complexity.
Architecture defines a set of constraints on subsequent implementation.

2.2 What parameters (inputs) are typically used in models for analyzing performance
Answer:
Parameters (inputs) for analytic modeling of performance (candidates):
Arrival rate of events
queuing discipline
scheduling algorithm
service time for events
network topology 
network bandwidth
routing algorithm 

2.3 What is the difference between reference architecture and an architectural pattern? 
Answer:

An important difference between a pattern and reference architecture is that a pattern must be a recurrent solution that was already used on existing implementations. On the other hand, reference architecture can propose new, innovative solutions in its structure, whose usage was not yet proven in existing software. As a consequence, reference architecture is more suitable to propose a structure for new domains, which are not still well established.

Patterns and reference architectures document solutions in different levels of granularity. While a pattern focus on a single problem and in a single recurrent solution, reference architecture usually considers the target domain as a whole.

Question:
Q.3. Write any five availability tactics for fault detection. Explain each one briefly. 

Answer
Below are the 5 availability tactics for fault detection:
Ping
– Client (or fault-detector) pings the server and gets response back
– To avoid less communication bandwidth- use hierarchy of fault-detectors,
the lowest one shares the same h/w as the server
Heartbeat
– Server periodically sends a signal
– Listeners listen for such heartbeat. Failure of heartbeat means that the server is dead
– Signal can have data (ATM sending the last txn)
Exception Detection
– Adding an Exception handler means error masking
Voting (TMR)
– Three identical copies of a module are connected to a voting system which compares outputs from all the three components. If there is an inconsistency in their outputs when subjected to the same input, the voting system reports error/inconsistency.
– Majority voting, or preferred component wins
Timer and Time-stamping
– If the running process does not reset the timer periodically, the timer triggers off and announces failure
- Time-stamping: assigns a timestamp (can be a count, based on the local clock) with a message in a decentralized message passing system. Used to detect inconsistency.