DSYS - DISTRIBUTED SYSTEMS EXAM 1
QUESTIONS AND ANSWERS
70 QUESTIONS AND ANSWERS
What is a distributed system? - ANSWER One in which hardware or software
components located at networked computers communicate and coordinate their
actions only by passing messages
Characteristics/Key Challenges of Distributed Systems - ANSWER 1.
Heterogeneity - many types of hardware and software; handled by middleware
and mobile code
2. Openness - seamless extension, easy to expand; requires interfaces,
communication mechanisms and standards
3.Security - CIA model
4.Scalability - add resources within appropriate costs
5.Failure Handing - Failures should be partial, not take down the whole system
6.Concurrency - independent processes run simultaneously; resources must be
managed
7.Transparency - system must be perceived as whole
8.Quality of Service - Reliable, secure, good performance; deadlines
Methods of Failure Handling - ANSWER Detect a failure
Mask the failure
Tolerate the failure
Recover from the failure
Redundancy
Types of Transparency - ANSWER Access - remote and local access use same
commands
Location - no physical address knowledge requirements
Concurrency - no interference between running processes
Replication - multiple instances of resource used without user knowledge of
existence
Failure - faults must be concealed so processes and applications can continue to
run
Mobility - resources and clients in a system are able to move
, Performance - system can reconfigure based on loads
Scale - system can increase in size without change to structure or applications
Want for distributed systems - ANSWER Sharing of resources allows for
significantly higher power than any individual computer. Allows performing of
tasks that wouldn't happen otherwise. Allows communications and
collaborations to exist that wouldn't otherwise
Message Passing - ANSWER a relationship between objects permitting
communication; transmission of information
Resource Sharing - ANSWER Allowing multiple devices and processes access
to available resources in a system. The key goal of distributed systems
No Global Clock - ANSWER There is no perfect clock synchronization in a
distributed system. Clocks can drift, so no part of a system can know the exact
time of any other part of the system
Trends in Distributed Systems - ANSWER Pervasive Networking -
Collections of connected networks
Ubiquitous computing - Computing embedded into everyday objects
Mobile Computing - Being able to perform tasks on the go
Multimedia Services - media access and streaming
Systems as a Utility - resource sharing
Client - ANSWER Computer that sends a request to a server
Server - ANSWER Computer that fulfills a request for a client
Remote Invocation - ANSWER complete interaction between a client and
server
Request for Comments (RFC) - ANSWER A series of documents and notes on
standards
used or proposed for use on the Internet; each is identified by a number.
Middleware - ANSWER A software layer used to mask heterogeneity
QUESTIONS AND ANSWERS
70 QUESTIONS AND ANSWERS
What is a distributed system? - ANSWER One in which hardware or software
components located at networked computers communicate and coordinate their
actions only by passing messages
Characteristics/Key Challenges of Distributed Systems - ANSWER 1.
Heterogeneity - many types of hardware and software; handled by middleware
and mobile code
2. Openness - seamless extension, easy to expand; requires interfaces,
communication mechanisms and standards
3.Security - CIA model
4.Scalability - add resources within appropriate costs
5.Failure Handing - Failures should be partial, not take down the whole system
6.Concurrency - independent processes run simultaneously; resources must be
managed
7.Transparency - system must be perceived as whole
8.Quality of Service - Reliable, secure, good performance; deadlines
Methods of Failure Handling - ANSWER Detect a failure
Mask the failure
Tolerate the failure
Recover from the failure
Redundancy
Types of Transparency - ANSWER Access - remote and local access use same
commands
Location - no physical address knowledge requirements
Concurrency - no interference between running processes
Replication - multiple instances of resource used without user knowledge of
existence
Failure - faults must be concealed so processes and applications can continue to
run
Mobility - resources and clients in a system are able to move
, Performance - system can reconfigure based on loads
Scale - system can increase in size without change to structure or applications
Want for distributed systems - ANSWER Sharing of resources allows for
significantly higher power than any individual computer. Allows performing of
tasks that wouldn't happen otherwise. Allows communications and
collaborations to exist that wouldn't otherwise
Message Passing - ANSWER a relationship between objects permitting
communication; transmission of information
Resource Sharing - ANSWER Allowing multiple devices and processes access
to available resources in a system. The key goal of distributed systems
No Global Clock - ANSWER There is no perfect clock synchronization in a
distributed system. Clocks can drift, so no part of a system can know the exact
time of any other part of the system
Trends in Distributed Systems - ANSWER Pervasive Networking -
Collections of connected networks
Ubiquitous computing - Computing embedded into everyday objects
Mobile Computing - Being able to perform tasks on the go
Multimedia Services - media access and streaming
Systems as a Utility - resource sharing
Client - ANSWER Computer that sends a request to a server
Server - ANSWER Computer that fulfills a request for a client
Remote Invocation - ANSWER complete interaction between a client and
server
Request for Comments (RFC) - ANSWER A series of documents and notes on
standards
used or proposed for use on the Internet; each is identified by a number.
Middleware - ANSWER A software layer used to mask heterogeneity
