csci 387 quiz 5

Question 1

benefits of distributed systems

Answer 1

• can be scaled to cope with increasing demand
• can continue to provide user services if parts of the system fail
• enable resources to be shared

Question 2

issues to be considered in the design of distributed systems

Answer 2

transparency, openness, scalability, security, quality of service, failure management

Question 3

client-server systems are structured into ?

Answer 3

layers

Question 4

the presentation layer of client-server systems is implemented on

Answer 4

a client computer

Question 5

client-server systems: servers provide

Answer 5

data management, application, and database services

Question 6

client-server systems may have several tiers with ?

Answer 6

different layers of the system distributed to different computers

Question 7

architectural patterns for distributed systems

Answer 7

master-slave, two-tier and multi-tier client-server, distributed component, and peer-to-peer

Question 8

distributed component systems require middleware to ?

Answer 8

handle component communications and to allow components to be added to and removed from the system

Question 9

peer-to-peer architectures are

Answer 9

decentralized with no distinguished clients and servers

Question 10

in peer-to-peer architectures, computations can be

Answer 10

distributed over many systems in different organizations

Question 11

software as a service is

Answer 11

a way of deploying applications as thin client-server systems, where the client is a web browser

Question 12

distributed systems are (more/less) complex than systems that run on a single processor

Answer 12

more

Question 13

the types of attack that a distributed system must defend itself against are

Answer 13

interception, interruption, modification, fabrication

Question 14

two types of interaction between components in a distributed system

Answer 14

1. procedural (one computer calls on a known service offered by another and waits for a response)
2. message-based (the sending computer sends info about what is required to another computer - not necessary to wait for a response)`

Question 15

in master-slave architecture, the ‘master’ process is usually responsible for

Answer 15

computation, coordination, and communications (controls the slave processes)

Question 16

in master-slave architecture, the ‘slave’ processes are

Answer 16

dedicated to specific actions

Question 17

in a two-tier client-server architecture, the system is implemented as

Answer 17

a single logical server plus an indefinite number of clients that use that server

Question 18

thin-client model

Answer 18

the presentation layer is implemented on the client and all other layers are implemented on a server

Question 19

fat-client model

Answer 19

some of all of the application processing is carried out on the client; data management and database functions are implemented on the server

Question 20

disadvantage of thin-client model

Answer 20

places a heavy processing load on both the server and the network

Question 21

the fat-client model is most suitable for

Answer 21

new systems where the capabilities of the client system are known in advance

Question 22

disadvantage to the fat-client model

Answer 22

new versions of the application have to be installed on all clients

Question 23

benefits of distributed component architecture

Answer 23

system designer can delay decisions on where/how services are provided, allows new resources to be added as required, flexible, scalable, possible to reconfigure the system dynamically

Question 24

disadvantages of distributed component architecture

Answer 24

more complex to design, standardized middleware never been accepted

Question 25

? are the principal reason by p2p architectures are not widely used because ?

Answer 25

security concerns; the lack of central management means that malicious nodes can be set up to deliver spam and malware to other nodes in the network

Question 26

SaaS stands for ? and involves ?

Answer 26

Software as a Service; hosting the software remotely and providing access to it over the internet